Financial Tool
Simple Interest Calculator
Calculate the interest earned on a principal at a fixed rate, applied only to the original amount.
What is simple interest?
Simple interest is calculated exclusively on the original principal,
without reinvesting the interest earned. Each period generates the same fixed amount of interest,
producing linear growth over time.
Unlike compound interest —which reinvests returns and accelerates growth exponentially—
simple interest is straightforward and predictable. It is commonly used in
short-term loans, installment financing, and
fixed-term deposits where the principal remains unchanged throughout.
A = P × (1 + r × t)
A final amount
P principal
r annual rate
t years
I = P × r × t
📏 Linear growthInterest grows at a constant rate each year — no compounding effect.
🔒 Fixed baseThe rate always applies to the original principal, never to accumulated interest.
⚖️ Vs. compoundOver long periods, simple interest yields significantly less than compound interest at the same rate.
Parameters
€
%
yr
◈
Projection
Final amount
—
Total interest earned
—
Principal
—
Interest per year
—
Interest per month
—
Total return
—
Principal
Interest
| Year | Principal | Interest (year) | Cumul. interest | Total amount | Total return |
|---|