Technical Debt Calculator
Quantify the cost of technical debt from velocity impact, bug rates, and onboarding delays.
About this calculator
This calculator puts a dollar figure on technical debt by modeling three distinct drains on an engineering team's fully-loaded cost: slower feature velocity, extra bug-fixing time, and longer onboarding for new hires. Velocity loss and bug-fix cost are both calculated as a straight percentage of total team cost (headcount times average loaded cost), so they scale directly with team size and your own estimates of how much debt slows delivery and how much time goes into debt-caused bugs. The onboarding penalty is more specific: it estimates how many developers you'll hire in a year from your turnover rate, assumes technical debt adds roughly 50% to a clean-codebase onboarding timeline, and prices that extra ramp-up time at a weekly developer cost. These three add up to an annual — and monthly — cost of carrying the debt as-is.
Remediation cost assumes a dedicated strike team of about 30% of the engineering org working for your estimated number of weeks, and payback period simply divides that cost by the monthly debt cost to show how many months until the investment breaks even. A separate growth projection compounds the annual cost forward 12 months at your specified monthly growth rate, illustrating how debt left unaddressed gets more expensive, not static — and the two-year savings figure assumes remediation eliminates 80% of the ongoing cost, comparing that against doing nothing while debt keeps compounding. These are directional estimates built on stated assumptions, not measured productivity data, so treat the multipliers as levers to sanity-check against your team's own experience.
Inputs
Results
Annual cost of tech debt
$542,308.00
Monthly cost of tech debt
$45,192.00
How to Use This Calculator
- Enter the number of Developers and Average Developer Cost per Year.
- Set Velocity Loss % and Bug Fix Time % — the portion of sprints lost to tech debt.
- Input Base Onboarding Weeks and Annual Turnover % to capture knowledge transfer costs.
- Set Estimated Remediation Effort (weeks) and Monthly Debt Growth Rate %.
- Review Annual Cost of Tech Debt and Monthly Debt Cost to build the business case for a refactoring investment.
How the result changes with Number of developers
| Number of developers | Annual cost of tech debt | Monthly cost of tech debt |
|---|---|---|
| 5 | $271,154.00 | $22,596.00 |
| 7.5 | $402,404.00 | $33,534.00 |
| 15 | $804,808.00 | $67,067.00 |
| 25 | $1,347,115.00 | $112,260.00 |
What each input means
- Number of developers
- Size of the engineering team affected by tech debt.
- Avg developer cost/year ($)
- Fully-loaded annual cost per developer (salary + benefits + overhead).
- Velocity loss %
- Percentage of development velocity lost to working around tech debt.
- Bug fix time %
- Percentage of developer time spent fixing debt-related bugs.
- Base onboarding (weeks)
- Weeks to onboard a new developer in a clean codebase.
- Annual turnover %
- Yearly developer turnover rate.
- Remediation effort (weeks)
- Estimated calendar weeks to address the major tech debt items.
- Monthly debt growth %
- Rate at which tech debt compounds monthly if left unaddressed.
What each result means
- Annual cost of tech debt
- Total yearly cost from velocity loss, bugs, and onboarding delays.
- Monthly cost of tech debt
- Monthly drag on the engineering organization.
- Velocity loss cost / year
- Annual cost of developers working slower due to tech debt.
- Bug fix cost / year
- Annual cost of fixing debt-induced bugs.
- Onboarding penalty / year
- Extra cost from extended onboarding for new hires.
- Remediation cost
- One-time cost to address tech debt with a dedicated team.
- Remediation team size
- Recommended number of developers for remediation (~30% of team).
- Payback period (months)
- Months until remediation investment pays for itself.
- 2-year net savings
- Net savings over 2 years from remediating now vs. doing nothing.
- Debt cost in 12 months
- Projected annual debt cost in 12 months if growth continues.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersNumber of developers = 10, Avg developer cost/year ($) = 150000, Velocity loss % = 20, Bug fix time % = 15 = 8 input(s) provided
- Calculate Annual cost of tech debtAnnual cost of tech debt = velocityLossCostPerYear + bugFixCostPerYear + onboardingPenaltyCost542308 = $542,308
- Calculate Monthly cost of tech debtMonthly cost of tech debt = annualDebtCost / 1245192 = $45,192
- Calculate Velocity loss cost / yearVelocity loss cost / year = teamCostPerYear * (velocityLossPct / 100)300000 = $300,000
- Calculate Bug fix cost / yearBug fix cost / year = teamCostPerYear * (bugFixTimePct / 100)225000 = $225,000
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
How does the calculator turn a turnover rate into an onboarding cost?
It multiplies your Number of Developers by Annual Turnover % to estimate how many new hires you'll bring on in a year, then assumes technical debt adds 50% to the Base Onboarding Weeks you entered — a developer who'd ramp up in 6 weeks on clean code takes 3 extra weeks in a debt-laden one. Those extra weeks are priced at a weekly developer cost (annual cost divided by 52) and multiplied by the projected new-hire count to get onboardingPenaltyCost.
Why are Velocity Loss % and Bug Fix Time % both applied to the same total team cost?
Both percentages are independent multipliers against teamCostPerYear (developers × average loaded cost), representing two separate drains rather than one split budget — velocityLossCostPerYear models slower feature delivery, and bugFixCostPerYear models time spent fixing debt-caused defects, so they're added together rather than sharing a pool. If you set both to high values, they compound into a larger annualDebtCost, since the calculator doesn't assume the two effects overlap.
What does the two-year savings figure assume about how well remediation works?
It assumes remediation reduces the ongoing annual debt cost by 80%, leaving 20% of the current annualDebtCost as a residual even after the fix (twoYearCostWithRemediation = remediationCost + annualDebtCost × 0.2). It compares that against a no-action scenario where debt cost grows for a year at your Monthly Debt Growth Rate compounded forward, so the size of the projected savings is sensitive to how aggressive that growth assumption is.
Why might the payback period be misleading for a team with low turnover?
Payback Period divides remediationCost by monthlyDebtCost, and monthlyDebtCost only includes velocity loss, bug-fix time, and onboarding penalty — a team with near-zero turnover contributes little from the onboarding term, so its monthly debt cost (and therefore its payback period) is driven almost entirely by the Velocity Loss % and Bug Fix Time % you estimate, which are the least directly measurable of the three inputs.
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