Calwarden

Build vs Buy Calculator

Compare building internally versus buying a vendor solution with user-entered development, maintenance, subscription, and implementation costs.

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Inputs

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$/year
$/year
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$
$/year

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Results

Build Savings vs Buy
Build Total Cost$560,000.00
Buy Total Cost$620,000.00
Lower-Cost OptionBuild

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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.

Sensitivity preview

Build Upfront Cost -10%: Build Savings vs Buy $78,000.00

Build Upfront Cost Current: Build Savings vs Buy $60,000.00

Build Upfront Cost +10%: Build Savings vs Buy $42,000.00

Formula: 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.

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About this Build vs Buy Calculator

Build-versus-buy decisions often mix engineering effort, vendor subscription cost, implementation work, maintenance, and opportunity cost.

Who this calculator is for

  • Procurement, finance, operations, and vendor-management teams comparing sourcing options.
  • Small business owners checking supplier quotes before approving a spend decision.
  • Analysts preparing a transparent savings estimate from user-entered contract, discount, and cost assumptions.

When to use it

  • Compare a current vendor baseline against a proposed sourcing option.
  • Separate gross savings from transition, implementation, maintenance, or administration costs.
  • Document the assumptions behind a negotiation, renewal, consolidation, lease, or build-versus-buy recommendation.

How to use this calculator

  1. Enter only prices, discounts, quantities, terms, and costs you can verify from your quotes, contracts, invoices, or planning model.
  2. Adjust one assumption at a time to compare conservative, expected, and optimistic cases.
  3. Use the primary output as a planning estimate and review the supporting outputs before making a decision.

Key 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.

Accuracy and testing

Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.

View accuracy page

How this calculator works

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

Inputs explained

Baseline spend

The current price, annual spend, quantity, or existing vendor cost you want to compare against.

Proposed pricing

The quoted price, lease payment, purchase price, subscription cost, or discount entered by the user.

One-time and ongoing costs

Implementation, transition, maintenance, administration, residual value, or internal labor costs included in the estimate.

Understanding your results

A positive build savings result means building is lower cost in the scenario you entered. A negative value means buying is lower cost by the absolute value of the result.

Example scenarios

Practical scenario

A $180,000 internal build with $95,000 annual support compared with a $60,000 implementation and $140,000 annual subscription over 4 years shows whether build or buy is lower cost on entered costs alone.

Key Features

  • Instant Calculation
  • Private & Secure
  • Mobile Optimized

Tips & Best Practices

  • Keep one-time implementation or transition costs separate from recurring savings.
  • Run a downside case with lower discounts, higher maintenance, or slower adoption before committing.
  • Confirm supplier terms, renewal clauses, usage minimums, cancellation costs, service levels, and data requirements outside the calculator.

Frequently Asked Questions

Should I treat this as procurement advice?
No. This is transparent planning math based on your inputs. Review supplier terms, service levels, tax treatment, legal obligations, and operational risk before making a sourcing decision.
Is vendor pricing or cost data uploaded?
No. These calculators run locally in your browser. Calwarden does not store, transmit, or review the prices, discounts, costs, or contract assumptions you enter.
Does this include strategic fit or implementation risk?
No. It compares costs only. Feature fit, security, compliance, support, roadmap control, opportunity cost, and delivery risk should be evaluated separately.