justyourcalculatorSimple Interest Calculator
Simple interest with I = P × r × t, solved for whichever number you need.
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Simple Interest Calculator
Interest, principal, rate or time with I = Prt
Interest earned
$3,000.00
- Principal
- $10,000.00
- Interest rate
- 3% per year
- Time
- 10 years
- Interest
- $3,000.00
- Ending balance
- $13,000.00
- Principal$10,000
- Interest$3,000
How it was calculated
- I = P × r × t = $10,000.00 × 0.03 × 10 = $3,000.00
- A = P + I = $13,000.00
| Year | Interest | Total interest | Balance |
|---|---|---|---|
| Year 1 | $300.00 | $300.00 | $10,300.00 |
| Year 2 | $300.00 | $600.00 | $10,600.00 |
| Year 3 | $300.00 | $900.00 | $10,900.00 |
| Year 4 | $300.00 | $1,200.00 | $11,200.00 |
| Year 5 | $300.00 | $1,500.00 | $11,500.00 |
| Year 6 | $300.00 | $1,800.00 | $11,800.00 |
| Year 7 | $300.00 | $2,100.00 | $12,100.00 |
| Year 8 | $300.00 | $2,400.00 | $12,400.00 |
| Year 9 | $300.00 | $2,700.00 | $12,700.00 |
| Year 10 | $300.00 | $3,000.00 | $13,000.00 |
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How the simple interest calculator works
Simple interest is paid only on the original principal: I = P × r × t, where r is the yearly rate as a decimal and t the time in years. The ending balance is A = P × (1 + r × t).
Rearranging the same formula gives the principal (P = A / (1 + rt)), the rate (r = (A/P - 1) / t) or the time (t = (A/P - 1) / r). Days are counted as 1/365 of a year.
Most savings accounts and loans actually compound, where interest earns interest. Simple interest is used for many car loans, short-term loans and some bonds.
Using and checking your result
Published by JustYourCalculator. Check the units and assumptions above, and compare a known example before relying on the output. Calculations use browser arithmetic and may round displayed values.
This is an educational estimate, not a lender quote, tax filing calculation or investment recommendation. Actual costs depend on current rules, fees and your circumstances. Verify important decisions with official sources and a qualified adviser.
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