Build vs. Buy Calculator

What This Calculator Does

This calculator helps you compare the total cost and expected return of building a custom solution in-house versus buying an existing product or service. It factors in development time, ongoing maintenance, licensing fees, and projected value to give you a clearer financial picture before making a strategic decision.

How the Comparison Works

The calculator evaluates both options across several key dimensions to produce a side-by-side cost and value comparison.

Build Costs

Includes estimated development hours, hourly or fixed development rates, infrastructure costs, and ongoing maintenance and support expenses over a defined period.

Buy Costs

Includes upfront licensing or subscription fees, implementation and integration costs, and any recurring renewal or support fees.

Value and ROI

Both options are assessed against the expected value the solution will deliver, such as revenue impact, operational savings, or productivity gains. The calculator estimates the return on investment for each path based on your inputs.

How to Use the Calculator

1. Enter your build estimates. Provide the number of development hours, your hourly rate, and any ongoing monthly maintenance costs.
2. Enter your buy estimates. Provide the upfront license or subscription cost, implementation fees, and any recurring renewal costs.
3. Set the expected value. Estimate the total value the solution will generate over a chosen time period.
4. Review the comparison. The calculator will display total costs, net value, and ROI for both options side by side.

Example Scenario

A team needs a customer analytics dashboard. They estimate building it in-house would take 400 hours at $150/hour, with $500/month in ongoing maintenance. Buying a similar tool costs $12,000 upfront with a $2,000 annual renewal. They expect the solution to deliver $80,000 in value over two years.

The calculator shows the build option costs $72,000 total with an ROI of 11%, while the buy option costs $16,000 total with an ROI of 400%. In this case, buying is clearly the better financial decision.

Understanding Your Results

The results page shows total cost, net value (value minus cost), and ROI percentage for each option. A higher ROI indicates a better return relative to the investment. The calculator also highlights the cost difference between the two paths.

Keep in mind that this is a financial comparison. It does not account for non-financial factors like control over features, vendor lock-in, team expertise, or strategic alignment. Use the results as one input in a broader decision-making process.

Common Mistakes to Avoid

• Underestimating build costs. Development often takes longer and costs more than initially planned. Include buffer time and hidden costs like testing, documentation, and deployment.
• Ignoring ongoing maintenance. Both build and buy options have recurring costs. For build, this includes bug fixes, updates, and infrastructure. For buy, this includes renewal fees and support contracts.
• Overestimating value. Be realistic about the value the solution will deliver. Overly optimistic projections can skew the comparison.
• Forgetting integration costs. Both options may require integration with existing systems. Include these costs in your estimates.

Limitations of This Calculator

This calculator provides a simplified financial model. It does not account for qualitative factors such as team capacity, time to market, competitive advantage, or risk tolerance. The accuracy of the results depends entirely on the quality of your inputs. Use this tool as a starting point for discussion, not as a sole decision-maker.

Practical Use Cases

• Startups evaluating build vs. buy for core product features.
• Enterprise teams comparing custom development to SaaS solutions.
• Product managers justifying budget allocation to stakeholders.
• CTOs assessing long-term cost implications of technology decisions.