Calwarden
Back to calculator
Procurement & VendorsGenerated accuracy model review: 2026-05-06

Build vs Buy Calculator accuracy and testing

This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.

Formula source

  • Build total cost = build upfront cost + (internal annual labor cost + build annual maintenance cost) * years. Buy total cost = vendor upfront cost + implementation cost + annual subscription cost * years. Build savings vs buy = buy total cost - build total cost.

Test cases

Default input regression check

Generated from the checked-in default inputs and calculate function.

Inputs

  • Build Upfront Cost: $180,000
  • Internal Annual Labor Cost: 70,000 $/year
  • Build Annual Maintenance Cost: 25,000 $/year
  • Vendor Upfront Cost: $15,000
  • Implementation Cost: $45,000
  • Annual Subscription Cost: 140,000 $/year
  • Analysis Period: 4 years

Expected outputs

  • Build Savings vs Buy: $60,000.00
  • Build Total Cost: $560,000.00
  • Buy Total Cost: $620,000.00
  • Lower-Cost Option: Build

Known limitations

  • This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
  • Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

  • All prices, discounts, costs, volumes, terms, and rates are user-entered assumptions.
  • Calculations are deterministic and run locally in the browser without uploading procurement data.
  • Results are planning estimates and do not replace legal, accounting, tax, security, operational, or procurement review.

Unit handling

  • Build Upfront Cost accepts values in $.
  • Internal Annual Labor Cost accepts values in $/year.
  • Build Annual Maintenance Cost accepts values in $/year.
  • Vendor Upfront Cost accepts values in $.
  • Implementation Cost accepts values in $.
  • Annual Subscription Cost accepts values in $/year.
  • Analysis Period accepts values in years.
  • Build Savings vs Buy is displayed as currency.
  • Build Total Cost is displayed as currency.
  • Buy Total Cost is displayed as currency.

Rounding rules

  • Number displays use up to 2 decimal places in the calculator UI.
  • Currency outputs are displayed with standard US dollar formatting.
  • Input precision follows configured step values where provided.

Version history

1.0.0 - 2026-05-06

Generated accuracy and testing page from the current build-vs-buy-calculator calculator definition.

Change log

2026-05-06

Published default regression test documentation and metadata fallbacks for Build vs Buy Calculator.

Calculator transparency

Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.

Use calculator