Simple Interest Calculator Online Free
Simple Interest Calculator
Simple Interest Inputs
The initial amount of money
Annual interest rate
Length of investment or loan
How often interest is calculated
Quick Results
Final Results
Balance Breakdown
Balance Accumulation Over Time
Interest Payment Schedule
| Year | Interest | Balance | Total Interest |
|---|
Rate Comparison Analysis
Compare how different interest rates affect your final balance over 0 years.
The simple interest calculator computes the interest earned or owed on a principal amount at a fixed rate over a set period. Simple interest does not compound, making it straightforward to calculate and predict.
Simple Interest Formula
I = P x r x t A = P + I = P x (1 + r x t)
I = interest. P = principal. r = annual rate (decimal). t = time in years. A = total. Example: $3,000 at 6% for 2 years. I = $3,000 x 0.06 x 2 = $360. Total = $3,360.
Simple Interest Examples
| Principal | Rate | Time | Interest | Total |
|---|---|---|---|---|
| $1,000 | 5% | 1 year | $50 | $1,050 |
| $5,000 | 8% | 3 years | $1,200 | $6,200 |
| $10,000 | 4% | 5 years | $2,000 | $12,000 |
| $2,500 | 12% | 6 months | $150 | $2,650 |
Simple vs. Compound Interest Over Time
| Years | $10,000 at 6% Simple | $10,000 at 6% Compound (Annual) |
|---|---|---|
| 1 | $10,600 | $10,600 |
| 5 | $13,000 | $13,382 |
| 10 | $16,000 | $17,908 |
| 20 | $22,000 | $32,071 |
| 30 | $28,000 | $57,435 |
When Simple Interest Is Used
Simple interest appears in short-term personal loans, U.S. Treasury bills, some auto loans, and seller-financed real estate. It is also used in daily interest calculations on some mortgages. Simple interest is transparent and predictable because the interest charge never changes based on accumulated balance.
Frequently Asked Questions
How do I calculate simple interest?⌄
Multiply the principal by the interest rate (as a decimal) and by the time in years. For $2,000 at 5% for 3 years: I = $2,000 x 0.05 x 3 = $300. Total amount = $2,300.
What is the difference between simple and compound interest?⌄
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus all previously earned interest. Over many years, compound interest grows significantly faster at the same stated rate.
What is simple interest used for in everyday life?⌄
Simple interest is used in short-term personal loans, some car loans, U.S. Treasury bills, and savings bonds. Most long-term savings and investment accounts use compound interest.
How do I find the principal using simple interest?⌄
Rearrange the formula: P = I / (r x t). If you paid $450 in simple interest at 9% over 2.5 years: P = $450 / (0.09 x 2.5) = $2,000.
How do I find the rate using simple interest?⌄
Rearrange: r = I / (P x t). If you borrowed $5,000 for 2 years and paid $600 in interest: r = $600 / ($5,000 x 2) = 0.06 = 6% per year.