Simple Interest Calculator

Select what you want to solve for, then fill in the other three values:

• Interest Amount - calculate total interest earned or owed.
• Principal - find how much to invest to earn a target interest amount.
• Interest Rate - find the rate given principal, time, and interest amount.
• Time - find how long until a given interest amount is earned.

I = P * r * t

Where:
I = Interest amount
P = Principal
r = Annual interest rate (decimal)
t = Time in years

Total Amount = P + I = P(1 + rt)

Example: $10,000 at 5% for 3 years = $10,000 x 0.05 x 3 = $1,500 interest, $11,500 total.