Mortgage Constant Calculator
Annual debt service per unit of loan — the constant lenders and band-of-investment appraisals are built on.
Formula
When the cap rate exceeds the mortgage constant, leverage is positive — borrowed money raises your equity yield. The constant always exceeds the interest rate (it includes principal); shorter amortization raises K, which is why 25-year commercial debt squeezes DSCR harder than 30-year.
Not financial advice — for informational and analytical use only. Verify all figures with a qualified professional before acting on them.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Need mortgage constant calculator results fast? Analysts, founders, traders and finance professionals use the Mortgage Constant Calculator to skip the spreadsheet and get a defensible answer in one step — free, private and instant.
About Mortgage Constant Calculator
Annual debt service per unit of loan — the constant lenders and band-of-investment appraisals are built on. When the cap rate exceeds the mortgage constant, leverage is positive — borrowed money raises your equity yield. The constant always exceeds the interest rate (it includes principal); shorter amortization raises K, which is why 25-year commercial debt squeezes DSCR harder than 30-year. The governing relationship is K = 12 × [r/12 / (1 − (1+r/12)^−12n)]. The Mortgage Constant Calculator computes entirely in your browser — free, private (your figures never leave your device) and instant, recalculating live as you change any input.
How to use Mortgage Constant Calculator
- 1Enter Interest rate (%), Amortization (years) into the Mortgage Constant Calculator.
- 2The result is computed automatically using K = 12 × [r/12 / (1 − (1+r/12)^−12n)] — there is no button to press.
- 3Change any input to model a different scenario, then copy or share the result.
Why use Mortgage Constant Calculator?
- ✓Computes mortgage constant calculator instantly with the correct formula — no spreadsheet needed
- ✓100% free and unlimited, with no sign-up, login or paywall
- ✓Runs entirely in your browser, so the figures you enter stay private
- ✓Shows the formula, a live worked example and references so you can defend the number
Frequently asked questions
What is the formula behind the Mortgage Constant Calculator?+
Mortgage Constant Calculator uses K = 12 × [r/12 / (1 − (1+r/12)^−12n)]. When the cap rate exceeds the mortgage constant, leverage is positive — borrowed money raises your equity yield. The tool substitutes your actual inputs into this relationship and shows the worked example step by step.
What inputs does the Mortgage Constant Calculator need?+
Enter Interest rate (%), Amortization (years) and the result updates immediately — there is no button to press. Change any value to model a different scenario in real time.
Is the Mortgage Constant Calculator free, and is my data private?+
Yes — it is completely free with no sign-up or usage limit, and it runs entirely in your browser, so the numbers you enter are never uploaded or stored on any server. It is for informational and analytical use, not financial advice.
What should I watch out for when using the Mortgage Constant Calculator?+
The constant always exceeds the interest rate (it includes principal); shorter amortization raises K, which is why 25-year commercial debt squeezes DSCR harder than 30-year.
What is the Mortgage Constant Calculator based on?+
The method follows authoritative sources: Appraisal Institute — mortgage-equity techniques. The formula and references are shown on the page so you can verify and cite the result.
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