Top BPO Companies in the World
-
Featured
What are Featured Providers?
$1,000+< $25 / hr1,000 - 9,999Chicago, ILServices provided
See all 28 projectsHugo Inc. | Top CX Provider is an outsourcing company specializing in customer experience (CX) and support services. The company consistently receives high praise for its effective project management and adaptability, with 100% of reviewers noting the team's ability to seamlessly integrate into existing operations. Approximately 70% of the feedback highlights the company's impressive cultural fit and commitment to quality, with measurable outcomes like increased efficiency and customer satisfaction.
$1,000+< $25 / hr1,000 - 9,999Angeles, PhilippinesServices provided
See all 7 projectsConnext is a versatile outsourcing agency providing call center, accounting, and business process management services. Reviews indicate a strong focus on client alignment, effective recruitment, and seamless integration into clients' workflows, with over 85% of feedback emphasizing their impressive hiring speed and communication. Clients appreciate their proactive approach and dedication to long-term partnerships, although some suggest enhanced employee training.
$1,000+< $25 / hr50 - 249Sofia, BulgariaServices provided
See all 9 projectsMarKam Solutions is a versatile outsourcing provider specializing in technical support, sales, operations, and customer service. Across multiple reviews, clients commend their professional management, alignment with company values, and ability to meet budget constraints. With over 90% positive feedback, MarKam Solutions is praised for their adaptability, responsiveness, and the strategic impact on metrics such as customer satisfaction and sales growth.
-
$1,000+< $25 / hr10 - 49
Services provided
Launched in 2017, ACCESS LB Consultancy is a Back Office Outsourcing company. The company provides Back Office Outsourcing and Staffing, and is small.
Read more -
UndisclosedUndisclosed10 - 49
Services provided
Branding company Buiz Lab is in Madurai, India. They focus on Branding and Social Media Marketing.
Read more -
Featured
What are Featured Providers?
$100,000+Undisclosed10,000+Singapore, SingaporeServices provided
See all 12 projectsTDCX is a prominent business process outsourcing (BPO) company that specializes in providing global quality evaluations, customer support, and scalable operations solutions across various sectors such as hospitality, social media, fintech, and e-commerce. Clients frequently praise TDCX for their agility, reliability, and exceptional communication skills, with a focus on collaborative and innovative problem-solving approaches. Approximately 95% of feedback highlights their ability to consistently exceed expectations and deliver high-quality service, with numerous clients noting their impressive capacity for scaling operations without compromising quality. Some areas for improvement mentioned include exploring more competitive costing and flexible remote work options. Overall, TDCX maintains a strong reputation as a reliable and effective partner in enhancing customer experience and operational efficiency.
UndisclosedUndisclosed250 - 999Torreón, MexicoServices provided
See all 24 projectsRemote Team Solutions is a staffing company specializing in recruiting and managing remote teams across various industries. The reviews highlight their strength in sourcing talent that aligns with company cultures, with approximately 100% of reviewers commending their dedication and professionalism. Clients consistently appreciate their responsive communication and timely project management, though a few noted the hiring process could sometimes be rushed.
$1,000+< $25 / hr50 - 249Portland, ORServices provided
See all 18 projectsTECHSPEED INC is a data management and business process outsourcing company, excelling in services like data entry, data cleaning, and customer support. Their reviews reveal an impressive track record of responsive project management and adaptability, with 100% of reviewers expressing satisfaction and no identified areas for improvement. Notably, clients highlight their efficiency, proactive communication, and ability to handle complex data projects with precision.
-
Undisclosed< $25 / hr10 - 49
Services provided
Virtual soft cloud is a Sales Outsourcing company. They offer Sales Outsourcing and Staffing and were founded in 2024. The agency is in Cairo, Egypt.
Read more -
$100,000+$150 - $199 / hr10 - 49Gurugram, India
Services provided
Small Architectural Design company Estate Avenues, is headquartered in Gurugram, India. The team focuses on Architectural Design and Video Production.
Read more -
$5,000+$25 - $49 / hr10 - 49
Services provided
IN-FLIGHT TEAMS is a custom software development company. They were founded in 2023 and offer Custom Software Development and Web Development.
Read more -
Undisclosed$25 - $49 / hr10 - 49
Services provided
Devcansol Private Limited is a Chennai, India-based SEO services firm. They focus on Search Engine Optimization and IT managed services.
Read more -
$1,000+$25 - $49 / hr10 - 49
Services provided
Business Consulting company DMA Business Strategist was founded in 2015. The team focuses on Business Consulting and Accounting.
Read more -
$1,000+< $25 / hr10 - 49
Services provided
AVE Enterprises is a graphic design company launched in 2024. The small team specializes in Graphic Design and Video Production.
Read more -
$1,000+$25 - $49 / hr10 - 49Mumbai, India
Services provided
Founded in 2023, ORBITAVANYA TECH LLP is a branding agency. Their services include Branding and Digital Strategy.
Read more -
$10,000+$50 - $99 / hr10 - 49
Services provided
HiveMind Ventures Pte Ltd is a Digital Strategy company. The team specializes in Digital Strategy and IT strategy consulting and is in Singapore, Singapore.
Read more -
UndisclosedUndisclosed10 - 49Sandton, South Africa
Services provided
Liquid Mash is a branding firm. The firm is in Sandton, South Africa. Their team focuses on Branding and IT managed services.
Read more -
UndisclosedUndisclosed10 - 49
Services provided
Fulfillment company Ship Apollo Inc was launched in 2019. The firm focuses on Fulfillment and Logistics & Supply Chain Consulting, and is small.
Read more -
$5,000+$100 - $149 / hr10 - 49
Services provided
Reabus is a Business Consulting company. They were launched in 2020 and specialize in Business Consulting and Back Office Outsourcing.
Read more -
$1,000+$100 - $149 / hr10 - 49
Services provided
Power Professor is a Lighting Design company. Headquartered in Portland, Oregon, their small team focuses on Lighting Design and Application Testing. The company was launched in 2019.
Read more -
$1,000+$25 - $49 / hr10 - 49
Services provided
Established in 2023, USA DIAGOANAL SERVICES is a small web design agency. Their team provides Web Design and UX/UI Design.
Read more -
$10,000+$50 - $99 / hr10 - 49Dubai, United Arab Emirates
Services provided
The Capital Zone is a big data company. Their small team of employees is in Dubai, United Arab Emirates. Their team provides BI & big data consulting & SI and IT managed services.
Read more -
$5,000+< $25 / hr10 - 49
Services provided
Zone10X is a Business Consulting company. Their small team of employees is headquartered in Dubai, United Arab Emirates. Their team provides Business Consulting and Document Digitization &
Read more -
$1,000+$150 - $199 / hr10 - 49Lytchett Matravers, England
Services provided
TACLADDERS IT SOLUTIONS PVT LTD is a small branding agency based in Lytchett Matravers, England and Ambala Cantt, India. Their services include Branding and Conversion Optimization.
Read more -
$1,000+Undisclosed10 - 49
Services provided
Located in Cotonou, Benin, SIONTEL is a Market Research company. Launched in 2020, the team focuses on Market Research and Call Center Services.
Read more -
$1,000+< $25 / hr10 - 49Ahmedabad, India
Services provided
Launched in 2024, James infotech solutions is a small Data Annotation Services company located in Ahmedabad, India. Their team offers Data Annotation Services and Web Development.
Read more -
$1,000+Undisclosed10 - 49
Services provided
Founded in 2024, Engage365.biz is a small managua, Nicaragua-based Advertising company. Their team specializes in Advertising and Digital Strategy.
Read more -
UndisclosedUndisclosed10 - 49
Services provided
Cureeya, a PR company, offer Public Relations and Search Engine Optimization. They were founded in 2019.
Read more -
$1,000+Undisclosed10 - 49
Services provided
Zeekeo is a Market Research company. They focus on Market Research and Email Marketing and were established in 2025. The firm is based in Calgary, Canada.
Read more -
$1,000+$50 - $99 / hr10 - 49Brampton, Canada
Services provided
Empower Media Group is a branding company launched in 2023. Their team specializes in Branding and Social Media Marketing.
Read more -
$1,000+< $25 / hr10 - 49Rajkot, India
Services provided
DigiMIrchi Infotech is a branding company. They were established in 2024 and provide Branding and Search Engine Optimization.
Read more -
$1,000+$25 - $49 / hr10 - 49Salem, India
Services provided
Nulinz Global Technology is a Digital Strategy company. They provide Digital Strategy and BI & big data consulting & SI and are headquartered in Salem, India.
Read more -
$1,000+< $25 / hr10 - 49
Services provided
Established in 2020, Bravilio is a Direct Marketing company. Their team provides Direct Marketing and Market Research.
Read more -
UndisclosedUndisclosed10 - 49
Services provided
Simply AI, an AI Agents company, is headquartered in Leeds, England. They provide AI Agents and Customer Service Outsourcing.
Read more -
$10,000+$25 - $49 / hr10 - 49
Services provided
Alpha Group is a web development company. The Dhaka, Bangladesh-based company offers Web Development and Custom Software Development.
Read more -
$1,000+Undisclosed10 - 49
Services provided
Managed Print Solutions UK Ltd is an IT strategy consulting company in High Wycombe, England and London, England. Founded in 2022, the team offers IT strategy consulting and cloud consulting & SI.
Read more -
Undisclosed< $25 / hr10 - 49
Services provided
Swenta Technologies is a Business Consulting company established in 2010. The company focuses on Business Consulting and Back Office Outsourcing, and is small.
Read more -
UndisclosedUndisclosed10 - 49
Services provided
Dial Edge Telecom is a small unified communications consulting & SI company. Founded in 2024, the team focuses on unified communications consulting & SI and cloud consulting & SI.
Read more -
Undisclosed< $25 / hr10 - 49
Services provided
Launched in 2025, Wise Word is a Business Consulting company. Their services include Business Consulting and Translation.
Read more -
UndisclosedUndisclosed10 - 49
Services provided
GALENUS, a Business Consulting company, is located in Giza, Egypt. They focus on Business Consulting and Transcription and were launched in 2020.
Read more -
$1,000+Undisclosed10 - 49
Services provided
Marlink Agency, a Digital Strategy company, was established in 2023. The agency specializes in Digital Strategy and Email Marketing.
Read more -
Undisclosed$25 - $49 / hr10 - 49
Services provided
Artham Law Chambers is a Mumbai, India-based Back Office Outsourcing company. Launched in 2021, the team focuses on Back Office Outsourcing and Finance & Accounting Outsourcing (FAO).
Read more -
$1,000+$25 - $49 / hr10 - 49Bengaluru, India
Services provided
Saintsmen Systems Private Limited is a branding company. Founded in 2023, their team focuses on Branding and BI & big data consulting & SI.
Read more -
UndisclosedUndisclosed10 - 49Mabitac, Philippines
Services provided
Graphic design agency JLR Consultancy was founded in 2020. The firm provides Graphic Design and Web Development.
Read more -
Undisclosed< $25 / hr10 - 49New Town, India
Services provided
THE CLICK CATALYSTS, a branding company, was established in 2024. The team specializes in Branding and Social Media Marketing and is located in New Town, India.
Read more -
Undisclosed< $25 / hr10 - 49Islamabad, Pakistan
Services provided
E Commerce Avenue Pvt LTD is a web development company launched in 2023. The company focuses on Web Development and Business Consulting, and is small.
Read more -
$10,000+$50 - $99 / hr10 - 49
Services provided
GM Business Solutions is a small ERP consulting and SI company founded in 2023. Their services include ERP consulting and SI and Business Consulting.
Read more -
$5,000+$50 - $99 / hr10 - 49
Services provided
Marketing Strategy company Byte Edge is based in Albuquerque, New Mexico. The team provides Marketing Strategy and Graphic Design.
Read more -
Undisclosed$25 - $49 / hr10 - 49
Services provided
Back Office Outsourcing company SF Business Solutions LLC is in Pflugerville, Texas. They provide Back Office Outsourcing and Finance & Accounting Outsourcing (FAO) and were launched in 2021.
Read more -
$1,000+< $25 / hr10 - 49Kochi, India
Services provided
GoForContent is a Content Writing Services company. They were founded in 2022 and focus on Content Writing Services and Content Marketing.
Read more -
$1,000+$25 - $49 / hr10 - 49
Services provided
Social media marketing company DK Digital was established in 2023. The company focuses on Social Media Marketing and Search Engine Optimization.
Read more -
$5,000+$25 - $49 / hr10 - 49
Services provided
In pune , India, leadbox is a Digital Strategy company. The team focuses on Digital Strategy and Social Media Marketing.
Read more -
$5,000+$25 - $49 / hr10 - 49
Services provided
TidyCounts Services LLP is a Back Office Outsourcing company. The agency is in Ahmedabad, India. Their team specializes in Back Office Outsourcing and Accounting.
Read more -
$1,000+$150 - $199 / hr10 - 49
Services provided
Narrative consultants, a public relations firm, focus on Public Relations and Marketing Strategy. They were founded in 2023.
Read more -
$1,000+$200 - $300 / hr10 - 49
Services provided
R2 Advisors PC, a small Business Consulting company, is headquartered in McLean, Virginia. The team focuses on Business Consulting and Back Office Outsourcing.
Read more -
$1,000+< $25 / hr10 - 49
Services provided
Established in 2025, Adybuzz is a branding agency. Based in Balaghat, India, the team focuses on Branding and Social Media Marketing.
Read more
Share your project goals, and we’ll connect you with verified partners who fit your budget and timeline.
Get My Matches
Tell us what you need — we’ll match you with top agencies in minutes.
Get My MatchesWhy Trust Clutch
At Clutch, we believe trust is the foundation of every business relationship. Our mission is to help buyers make confident, data-backed decisions informed by real client experiences.
Every review on Clutch undergoes a rigorous, human-led verification process to make sure it’s valid. Our team of specialists confirms the identity of each reviewer, ensures the project is legitimate, and only publishes reviews that meet our strict criteria.
Verification doesn’t stop at the point of publication. Our Trust & Safety team routinely audits older reviews against our guidelines. When reviews fall short of our standards, we remove them.
We evaluate service providers using a structured methodology that combines:
- In-depth client interviews and ratings
- Comprehensive project details
- Market presence
- Portfolio examples and industry recognition
This data powers tools like the Leaders Matrix, which helps you compare agencies directly. Our research team curates rankings by weighing verified reviews most heavily, so the most trusted and experienced providers rise to the top.
Using this unique combination of verified client feedback and provider-supplied insights, Clutch distills the most important details into clear, digestible summaries so you have everything you need to make confident, informed decisions quickly.
We take fraud seriously. Providers who violate our guidelines may face lower rankings, restricted visibility, or removal from the platform altogether.
Clutch’s commitment to transparency is ongoing. We’re constantly refining our systems to protect the integrity of reviews and support you in finding the right agency.
Compare Top 15 Business Processing Outsourcing (BPO) Companies & Services
-
$1,000+< $25 / hr250 - 999Portland, OR
Ability to deliver
39/40.019.2/20 Reviews10/10 Clients & Experience9.8/10 Market PresenceService focus
100% Back Office Outsourcing -
$1,000+< $25 / hr1,000 - 9,999Hollywood, FL
Ability to deliver
39/40.020/20 Reviews10/10 Clients & Experience9/10 Market PresenceService focus
75% Back Office Outsourcing25% Other -
$1,000+< $25 / hr1,000 - 9,999Gilbert, AZ
Ability to deliver
37.6/40.018/20 Reviews10/10 Clients & Experience9.6/10 Market PresenceService focus
55% Back Office Outsourcing45% Other -
$1,000+$25 - $49 / hr250 - 999Oakville, Canada
Ability to deliver
39.4/40.019.4/20 Reviews10/10 Clients & Experience10/10 Market PresenceService focus
80% Back Office Outsourcing20% Other -
UndisclosedUndisclosed1,000 - 9,999Los Angeles, CA
Ability to deliver
37.1/40.019.6/20 Reviews10/10 Clients & Experience7.5/10 Market PresenceService focus
100% Back Office Outsourcing -
$10,000+< $25 / hr250 - 999San Pablo City, Philippines
Ability to deliver
36.7/40.018/20 Reviews10/10 Clients & Experience8.7/10 Market PresenceService focus
90% Back Office Outsourcing10% Other -
$1,000+< $25 / hr250 - 999Dnipro, Ukraine
Ability to deliver
36.6/40.017/20 Reviews10/10 Clients & Experience9.6/10 Market PresenceService focus
100% Back Office Outsourcing -
$5,000+< $25 / hr1,000 - 9,999Lexington, KY
Ability to deliver
36.5/40.016.8/20 Reviews10/10 Clients & Experience9.7/10 Market PresenceService focus
80% Back Office Outsourcing20% Other -
$1,000+Undisclosed1,000 - 9,999New York, NY
Ability to deliver
36.2/40.020/20 Reviews10/10 Clients & Experience6.2/10 Market PresenceService focus
100% Back Office Outsourcing -
$5,000+< $25 / hr1,000 - 9,999Kyiv, Ukraine
Ability to deliver
36/40.019.8/20 Reviews9/10 Clients & Experience7.2/10 Market PresenceService focus
100% Back Office Outsourcing -
UndisclosedUndisclosed250 - 999
Ability to deliver
36/40.019.4/20 Reviews8.3/10 Clients & Experience8.2/10 Market PresenceService focus
80% Back Office Outsourcing20% Other -
$1,000+< $25 / hr50 - 249Chicago, IL
Ability to deliver
35.8/40.017/20 Reviews9.5/10 Clients & Experience9.3/10 Market PresenceService focus
100% Back Office Outsourcing -
$1,000+< $25 / hr1,000 - 9,999Chicago, IL
Ability to deliver
35.5/40.016.6/20 Reviews9.4/10 Clients & Experience9.5/10 Market PresenceService focus
70% Back Office Outsourcing30% Other -
$1,000+Undisclosed1,000 - 9,999Santa Monica, CA
Ability to deliver
35.4/40.015.8/20 Reviews10/10 Clients & Experience9.6/10 Market PresenceService focus
80% Back Office Outsourcing20% Other -
$1,000+< $25 / hr50 - 249Berkeley, CA
Ability to deliver
35.4/40.017.2/20 Reviews9.2/10 Clients & Experience9/10 Market PresenceService focus
100% Back Office Outsourcing -
Undisclosed< $25 / hr1,000 - 9,999Boise, ID
Ability to deliver
35.3/40.015.8/20 Reviews10/10 Clients & Experience9.5/10 Market PresenceService focus
80% Back Office Outsourcing20% Other -
$1,000+$25 - $49 / hr250 - 999Orlando, FL
Ability to deliver
35.3/40.016.2/20 Reviews10/10 Clients & Experience9.1/10 Market PresenceService focus
90% Back Office Outsourcing10% Other -
$1,000+< $25 / hr1,000 - 9,999Angeles, Philippines
Ability to deliver
35.2/40.016.8/20 Reviews10/10 Clients & Experience8.4/10 Market PresenceService focus
50% Back Office Outsourcing50% Other -
$1,000+< $25 / hr250 - 999Afton, WY
Ability to deliver
35.2/40.018.6/20 Reviews7.1/10 Clients & Experience9.5/10 Market PresenceService focus
90% Back Office Outsourcing10% Other -
$1,000+< $25 / hr250 - 999Doylestown, PA
Ability to deliver
35.1/40.017.4/20 Reviews8.7/10 Clients & Experience9/10 Market PresenceService focus
100% Back Office Outsourcing -
$1,000+Undisclosed250 - 999Brooklyn, NY
Ability to deliver
34.8/40.020/20 Reviews8.6/10 Clients & Experience6.2/10 Market PresenceService focus
75% Back Office Outsourcing25% Other -
$1,000+< $25 / hr50 - 249Kyiv, Ukraine
Ability to deliver
36.8/40.017.6/20 Reviews10/10 Clients & Experience9.2/10 Market PresenceService focus
90% Back Office Outsourcing10% Other -
$5,000+< $25 / hr1,000 - 9,999Cebu City, Philippines
Ability to deliver
34.5/40.018/20 Reviews10/10 Clients & Experience6.5/10 Market PresenceService focus
80% Back Office Outsourcing20% Other -
$1,000+< $25 / hr1,000 - 9,999Wilmington, DE
Ability to deliver
34.4/40.020/20 Reviews4.6/10 Clients & Experience9.8/10 Market PresenceService focus
75% Back Office Outsourcing25% Other -
$1,000+< $25 / hr250 - 999
Ability to deliver
34.3/40.016.6/20 Reviews7.9/10 Clients & Experience9.7/10 Market PresenceService focus
90% Back Office Outsourcing10% Other -
$10,000+< $25 / hr10,000+Pasig, Philippines
Ability to deliver
34.2/40.014.6/20 Reviews10/10 Clients & Experience9.6/10 Market PresenceService focus
100% Back Office Outsourcing -
$50,000+< $25 / hr10,000+Wei Fang Shi, China
Ability to deliver
34.1/40.015.8/20 Reviews10/10 Clients & Experience8.3/10 Market PresenceService focus
90% Back Office Outsourcing10% Other -
$5,000+$25 - $49 / hr50 - 249Austin, TX
Ability to deliver
34/40.017.2/20 Reviews10/10 Clients & Experience6.8/10 Market PresenceService focus
100% Back Office Outsourcing -
$5,000+$50 - $99 / hr250 - 999Calgary, Canada
Ability to deliver
33.8/40.016.4/20 Reviews9.8/10 Clients & Experience7.6/10 Market PresenceService focus
100% Back Office Outsourcing -
$5,000+Undisclosed50 - 249Laguna Beach, CA
Ability to deliver
39.6/40.020/20 Reviews10/10 Clients & Experience9.6/10 Market PresenceService focus
90% Back Office Outsourcing10% Other
Latest BPO Articles
See all articles
How to Choose a 3PL: 5 Mistakes E-Commerce Brands Make
Learn how to choose a 3PL that fits your channel mix, avoids hidden costs, and scales with your brand. Real selection criteria, and top providers compared.
Business Process Outsourcing Company FAQs
Looking for a BPO company but not sure where to start? Explore the top questions businesses are asking when looking for a BPO partner.
Clutch selects top-performing companies twice a year based on a proprietary methodology that evaluates industry expertise and the ability to deliver. The highest-rated BPO companies for Fall 2025 include:
A BPO company handles specific business processes such as customer support, payroll, data entry, or IT help desk on behalf of another organization. Acting as an extension of your team, the provider supplies trained staff, technology, and workflows to deliver those services at scale. This lets your in-house employees focus on core competencies while the BPO partner manages repeatable, back-office or customer-facing tasks with agreed-upon service-level agreements (SLAs).
BPO agencies typically cover three broad categories:
- Back-office support: data processing, accounting, HR administration, procurement
- Front-office support: call center operations, technical support, live chat, appointment setting
- Specialized or industry-specific processes: medical billing, legal transcription, mortgage processing
Many firms also bundle technology solutions such as CRM integrations, AI chatbots, and robotic process automation (RPA) to streamline workflows and improve accuracy.
Pricing varies by location, complexity, and volume. On Clutch, most projects start around $1,000 per month for simple data entry but can exceed $50,000 per month for multi-channel customer support. Hourly rates typically range from $8–$25 in offshore markets and $25–$60 in onshore markets. Always request a detailed cost breakdown (labor, technology, management fees) and clarify whether pricing is per FTE (full-time equivalent) or per transaction.
- Define goals: Identify the processes you want to outsource and the KPIs that matter (e.g., first-call resolution, turnaround time).
- Check domain expertise: Look for providers with proven results in your industry or process area.
- Review client feedback: Verified Clutch reviews reveal performance, communication style, and reliability.
- Evaluate scalability: Ensure the partner can add or reduce headcount quickly as demand changes.
- Assess security & compliance: Confirm certifications (ISO, SOC 2, HIPAA) and data-protection measures . Shortlist three vendors and run a pilot project or proof of concept before signing a long-term agreement.
- Opaque pricing or hidden fees
- Overpromising guaranteed results without data
- High employee turnover or insufficient training programs
- Poor communication or delayed responses during the sales process
- Lack of documented security protocols or compliance certifications
If any of these issues surface early, reconsider the partnership.
- How do you measure and report on performance metrics?
- What is your average agent tenure and training process?
- Which industries or processes make up most of your portfolio?
- Can you share recent case studies or client references?
- How do you handle data security, compliance, and disaster recovery?
- What is the escalation process for quality issues or SLA breaches?
Clear, detailed answers indicate a mature, reliable partner.
-
Onshore: Provider operates in the same country as the client—higher rates but easier collaboration and shared regulations.
-
Nearshore: Services are delivered from a neighboring or nearby time zone—balanced costs and cultural alignment.
-
Offshore: Operations are located in distant regions with lower labor costs—great for 24/7 coverage but may require more coordination.
They track cost savings, process accuracy, turnaround times, and customer satisfaction scores (CSAT or NPS). By comparing pre- and post-outsourcing metrics, clients can quantify improvements and calculate payback periods.