Simple Interest Calculator

How much simple interest will I earn or owe?

Single calculationv1.0.0Verified 2026-11-01Runs in your browser

Spec sheet

simple_interest · v1.0.0

Method

I = P × r × t

01I = P × r × t
02A = P + I
03Days use an actual/365 year

Limits — read before relying on it

No compounding; use the compound interest calculator for savings accounts.

Sources

Simple interest formulaformula

Worked example

computed by the same formula

$10,000 at 5 % for 3 years

Inputs

Principal: 10000
Annual rate: 5 %
Time: 3
Time unit: years

Result

Interest: $1,500.00
Principal + interest: $11,500.00

Questions

How is the simple interest calculated?

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I = P × r × t. I = P × r × t · A = P + I · Days use an actual/365 year

Example: $10,000 at 5 % for 3 years?

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Interest: $1,500.00; principal + interest: $11,500.00.

What does this calculator not cover?

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No compounding; use the compound interest calculator for savings accounts.

Where do the numbers come from?

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Sources: Simple interest formula. The formula is versioned (simple_interest v1.0.0) and covered by automated tests.

Is my data stored?

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No. The calculation runs in your browser and nothing is sent unless you choose to save a shareable link.

Also searched assimple interest calculator · simple interest formula · interest on a loan without compounding · i = prt

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Compound Interest Calculator

How much will my savings grow with compound interest and monthly deposits?

Bₜ₊₁ = Bₜ(1+i) + C