The everyday toolkit
Interest Calculator
Compare simple and compound interest with annual, quarterly, monthly or daily compounding.
Free · No account needed · Calculated in your browserEnter your values
Your result
A clear answer starts here.
Enter your values and choose Calculate to see the result. Changing a value clears the previous answer.
Results are rounded to two decimal places for display. Calculations use unrounded values. Use the same currency for all monetary inputs.
Use this calculator
- Choose a calculation mode when available and read the labels for its inputs.
- Enter your own values. Use consistent units and enter percentages as 10 for 10%, rather than 0.10.
- Select Calculate, then review all displayed results together with the formula and assumptions below.
- Change one value to compare scenarios. Use Reset to return to the worked example.
How this calculator works
Assumes a constant nominal annual rate with no additional deposits, withdrawals, fees or taxes. Fractional years are allowed and compound growth is modeled over that period.
Simple: interest = P × r × t. Compound: final amount = P × (1 + r ÷ n)ⁿᵗ, where n is the number of compounding periods per year.
Worked example
1,000 at 5% annual interest, compounded monthly for five years gives final amount of 1,283.36. The calculator also shows interest earned: 283.36. Use the form above to enter your own values. Monetary examples are in the same currency throughout.
Questions about this calculation
Does it include regular deposits?
No. The calculation assumes one starting amount, a constant nominal annual rate and no deposits, withdrawals, fees or taxes.
How do simple and compound interest differ?
Simple interest is calculated on the starting principal. Compound interest also grows previously earned interest according to the selected compounding frequency.