Loan Interest Rate Calculator
Work out the interest rate hidden in a loan from the amount, payment and term, and see the effective annual rate.
Quick answer
The loan interest rate is the periodic rate at which a level payment on your amount over your term equals the payment you entered. It cannot be rearranged directly, so it is solved numerically, then annualised as a nominal rate and an effective rate.
Loan Interest Rate Calculator
Annual Interest Rate (nominal)
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Effective Annual Rate (EAR)
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Rate per Payment Period
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Total Paid
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Total Interest
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Payment at Nearby Rates
| Annual rate | Payment (₹) | Total interest (₹) | Difference from your payment (₹) |
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Assumptions & method
- Level payments made at the end of each period for the whole term; number of payments n = term × payments per year, rounded to a whole number.
- The rate i per period is the value for which A = P × i × (1 + i)^n ÷ ((1 + i)^n − 1), solved by bisection between 0% and 100% per period. At i = 0 the payment is P ÷ n.
- Nominal annual rate = i × payments per year. EAR = (1 + i)^(payments per year) − 1.
- Total paid = payment × n; total interest = total paid − amount received. If total paid is below the amount received the result is a negative rate and is not shown.
- Fees, insurance, balloon payments, rate changes and irregular payments are not modelled. If fees were deducted from the loan, enter the net amount received to get an all-in rate. Estimates only, not advice.
Results are estimates based on the figures you enter. They are not guarantees and not financial advice.
Solving for the loan rate
When you know how much you borrowed, how much you pay each period and for how many periods, the interest rate is fixed by those numbers, but it cannot be rearranged out of the payment formula directly. The calculator therefore solves it numerically: it searches for the periodic rate at which a level payment on your amount over your term equals the payment you entered. It then converts that into a nominal annual rate and an effective annual rate (EAR), and shows nearby rates so you can see how sensitive the payment and the total interest are.