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Build vs Buy Calculator

Compare the total cost of ownership (TCO) for building custom software versus buying an off-the-shelf solution.
What This Calculator Helps You Do
Use the inputs below to test scenarios, compare outcomes, and interpret the result before acting on it.

Build vs Buy Calculator is designed to give you a fast answer, but it also provides supporting context such as formulas, worked examples, FAQs, and charts so the result is easier to validate.

For the best result, use realistic input values, review the assumptions in the explanation panels, and compare multiple scenarios if you are planning a decision based on the output.

Decision Context
Page-specific guidance for using this result in a real planning decision.

This finance calculator is intended to turn a specific business or money question into a repeatable estimate that is easier to compare and review.

Use it when you need a fast planning baseline before moving into a spreadsheet, lender discussion, management review, or more formal analysis.

The result is most useful when tested against several realistic assumptions, because financial decisions are usually sensitive to more than one input at a time.

Calculator
Enter your values
Analysis
Interpretation of the current calculator output

Enter values to see detailed analysis and insights.

How to Use

Step-by-step instructions
  1. 1Enter estimated internal development cost
  2. 2Add annual maintenance cost (usually 15-20% of build)
  3. 3Enter software purchase/setup fee
  4. 4Add annual subscription/license fees
  5. 5Set the analysis timeframe (e.g., 3 or 5 years)

Total Cost of Ownership (TCO)

Compares the long-term financial impact of building vs buying. Building has high upfront costs but lower variable costs. Buying has low upfront but higher recurring costs.
Build TCO = Initial Dev Cost + (Annual Maintenance × Years) Buy TCO = Setup Fee + (Annual Subscription × Years)

Variables:

Build TCOTotal cost to build and maintain
Buy TCOTotal cost to license and subscribe

Example

Software Decision Example

Inputs:

Build:$50k dev + $10k/yr maint
Buy:$5k setup + $12k/yr sub
Timeframe:3 years

Steps:

  1. 1.Build TCO = $50k + ($10k × 3) = $80,000
  2. 2.Buy TCO = $5k + ($12k × 3) = $41,000
  3. 3.Difference = $39,000 savings by buying
Result:
Buying is cheaper over 3 years

Frequently Asked Questions

When should I build?

Build when: The feature is a core competitive advantage, no existing solution meets requirements, or long-term scale makes buying prohibitively expensive.

When should I buy?

Buy when: It's a commodity function (CRM, email, payroll), speed to market is critical, or you lack internal engineering resources.

What are hidden costs?

Build: Technical debt, bug fixes, server costs, developer turnover. Buy: Implementation time, training, integration costs, price hikes.
In-depth guideBrowse Financial calculators
Build vs Buy Calculator Guide
Detailed usage notes, assumptions, mistakes to avoid, and related tools.

Build vs Buy Calculator helps turn the available inputs into a result that is easier to check, compare, and explain. Compare the total cost of ownership (TCO) for building custom software versus buying an off-the-shelf solution.

Use this page as part of the broader financial workflow when you need a repeatable calculation instead of a one-off estimate.

Formula And Variables
How the calculator turns inputs into an answer.

Total Cost of Ownership (TCO) is the main method behind this calculator. The equation is Build TCO = Initial Dev Cost + (Annual Maintenance × Years) Buy TCO = Setup Fee + (Annual Subscription × Years), and the calculator applies it consistently as you change the inputs.

The most important variables are: Build TCO is total cost to build and maintain, Buy TCO is total cost to license and subscribe. Check those values first if the output looks higher or lower than expected.

How To Use The Result
What to compare before acting on the output.

The worked example on this page uses Build = $50k dev + $10k/yr maint, Buy = $5k setup + $12k/yr sub, Timeframe = 3 years and produces Buying is cheaper over 3 years. Use that example as a quick check for the calculation flow before entering your own values.

For practical use, read the build vs buy calculator result as a decision-support number. It is strongest when you compare two or more scenarios using the same units and assumptions.

Data Visualization And Analysis
Different chart views answer different questions about the same calculator output.

Best ways to read the charts

Use a bar chart when you need to compare separate result components, a line or area chart when the output changes across steps or time, and a pie-style distribution when every value is part of one total.

When the page shows multiple chart tabs, start with the overview, then check the ranking view to see which value drives the result most strongly.

What the analysis should tell you

Compare the average, range, highest value, lowest value, and dominant contributor before making a conclusion from the main number alone.

If one value contributes most of the total, test that assumption first. If values are spread evenly, the result is usually driven by the full input set rather than a single outlier.

Common Mistakes
  • Do not mix units unless the calculator explicitly converts them for you.
  • Avoid copying a result without checking whether the inputs describe the same time period, measurement system, or scenario.
  • If the answer looks surprising, change one input at a time so you can identify which assumption is driving the output.
When The Result May Be Inaccurate

The result can be inaccurate if inputs use mixed units, rounded source data, outdated rates, or assumptions that do not match the situation being modeled.

Run a second scenario with conservative inputs when the output will affect a purchase, project, health decision, academic answer, or financial plan.

Build vs Buy Calculator is an educational planning tool. It should not replace advice from a qualified professional who can review the full context and current rules.

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Additional Questions

How accurate is Build vs Buy Calculator?

Build vs Buy Calculator is accurate for the formula and inputs shown on the page. Real-world accuracy depends on whether the values you enter are complete, current, and measured in the expected units.

What should I check before using the build vs buy calculator result?

Check the input units, review the formula section, compare the worked example, and run at least one alternate scenario if the result will support a decision.