Simple Interest Calculator
💷 Money & growth. Use the Simple interest formula to find interest, amount invested p, rate, time: pick the value you want, type the others, and the answer updates as you go.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Interest | £ |
| Amount invested P | £ |
| Rate | % per year |
| Time | years |
Worked example
Find the interest when Amount invested P = 1000 £, Rate = 5 % per year, Time = 3 years.
Using I = (P r t)/100: Interest = 150 £.
Frequently asked questions
What is the formula for Simple interest?
I = (P r t)/100.
What do the letters stand for, and what units are used?
Interest in £, Amount invested P in £, Rate in % per year, Time in years.
How do you calculate interest?
Put the values into I = (P r t)/100. For example, with Amount invested P = 1000 £, Rate = 5 % per year, Time = 3 years, interest = 150 £.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (interest, amount invested p, rate, time) and fill in the others: it rearranges the formula for you.
