How to calculate your interest
To begin your calculation, enter your starting amount along with the annual interest rate and the start date (assuming it isn’t today). Then, enter a number of years, months or days that the calculation is to run. Once you click the ‘calculate’ button, the simple interest calculator will show you:
- The interest accrued
- Your final value
- The split of final value
Simple interest calculator formula
Our calculator uses the following formula:
FV = P(1 + rt)
- FV = Final value (principal + interest)
- P = Principal (starting amount)
- r = Annual interest rate (as decimal)
- t = time period (in years)
Should you wish to work out the total interest only, simply calculate FV – P.
Example interest calculation
If an amount of $5,000 is invested at a yearly interest rate of 5%, with no compounding (simple interest), its value after 3 years can be calculated as follows…
P = 5000.
r = 5/100 = 0.05 (decimal).
t = 3.
Plugging those figures into the formula gives the following:
FV = 5000 * (1 + (0.05 * 3))
FV = 5000 * 1.15 = 5750
The balance after 3 years is therefore 5,750.