Loan Constant Calculator
Express annual debt service as a percentage of original loan principal.
Calculated directly from the assumptions shown.
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Move from this screening result to the complete Acquisition Financing Model.
Get the model · €49 incl. VATHow the Loan Constant calculation works
Loan constant = annual debt service ÷ original loan amount.
Example calculation
€675k of annual debt service on a €10m loan equals a 6.75% loan constant.
How professionals use the result
Use the loan constant to translate a DSCR constraint into loan capacity and compare amortising structures.
Common mistakes
- Using current balance instead of original principal without labelling it
- Using interest only instead of total debt service
- Mixing monthly and annual payments
- Ignoring fees
Loan Constant Calculator FAQs
What does the Loan Constant calculator measure?
Express annual debt service as a percentage of original loan principal.
What formula does the Loan Constant calculator use?
Loan constant = annual debt service ÷ original loan amount.
Is the result suitable for a final investment decision?
Use it as a transparent screening calculation. Validate deal-specific tax, timing, financing and legal assumptions in a complete underwriting model before making a decision.
Do I need an account?
No. The calculator is free and runs in your browser. FormulaPlanet does not store your projects, inputs or results.
Is any input sent publicly?
No calculation is public by default. A shareable link is only created when you explicitly choose to copy one; that link contains the assumptions shown in its URL.
Why might my spreadsheet give a different answer?
Differences usually come from timing, compounding, sign conventions, fees or a different definition of the numerator or denominator. Match every period and definition before comparing.
What should I review alongside this result?
Use the loan constant to translate a DSCR constraint into loan capacity and compare amortising structures.
Which mistakes are most common?
Using current balance instead of original principal without labelling it; Using interest only instead of total debt service; Mixing monthly and annual payments; Ignoring fees.