APR & Effective Interest Calculator

Estimate payment, fee-adjusted APR, effective annual rate, and total finance cost.

Results will appear here.

Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.

This tool runs in your browser. Inputs and results are not transmitted. If you explicitly save a scenario, its permitted fields stay in local browser storage until you clear them.

Share or report this tool

Page-sharing actions use the canonical page URL and do not include inputs or results unless a tool explicitly says otherwise.

Report a calculation issue
More options
Transparent methodology

How this calculator works

Reviewed July 2026

Formula

The payment uses the stated nominal rate and financed principal. Estimated APR solves the monthly discount rate that makes the payment stream equal net proceeds after fees, then annualizes that monthly rate. Effective annual rate compounds the solved monthly rate for twelve months.

Worked example

A $10,000, 36-month loan at 8% with $300 deducted upfront has a $313.36 payment, about 10.08% estimated fee-adjusted APR, 10.56% effective annual rate, and roughly $1,581 total finance cost relative to net proceeds.

Assumptions to verify

  • Payments are level, monthly, and made at the end of each period.
  • Fees are either deducted from proceeds or added to financed principal according to the selected option.
  • The estimate excludes insurance, irregular payment timing, prepayment, late charges, and jurisdiction-specific disclosure rules.

Frequently asked questions

Why is estimated APR above the stated rate?

Fees reduce proceeds or increase financed principal while payments remain higher, increasing the implied borrowing cost.

What is effective annual rate?

It compounds the solved monthly cost over twelve periods, unlike the nominal annualized APR estimate.

Will this exactly match a lender disclosure?

Not necessarily. Official calculations can use regulated charge definitions, exact dates, rounding, insurance, and other timing conventions.

Privacy: Inputs and results stay in this browser. Any future sponsored recommendation or advertisement will be clearly labeled and kept separate from the calculation.