Variable Interest Rate Compound Calculator

Use our Variable Interest Rate Compound Calculator to see how your money grows when its interest rate changes over time — a savings rate that goes up and down, a fixed-rate bond followed by a variable one — or to find the rate the last stretch needs to reach a target.

Enter each rate phase in order, with how long it lasts. Each phase starts from the balance the one before ended with. For example, $25,000 compounded monthly at 4% for 3 years grows to $28,181.80, then at 6% for 5 years to $38,013.02, and at 8% for 4 years to $52,293.22.

The equivalent annual rate sums up the whole path as one yearly rate — 6.34% in that example — even though no phase earned it. To compare it with the plain time-weighted average of your rates, without needing a balance, use our Average Interest Rate Over Time Calculator. Choose Rate needed to work backwards: $20,000 earning 5% for 4 years needs 6.02% for the next 6 years to reach $35,000. The rate is rounded up so the target is always reached.

No deposits, withdrawals, fees or taxes are included, so treat the results as an estimate. To add regular deposits at one rate, use our Compound Interest Calculator with Contributions; to see how much compounding itself adds, our Simple vs Compound Interest Calculator.