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➕ Simple Interest Calculator
Simple interest doesn't compound — it accrues only on the original principal. Used for many personal loans, auto loans, short-term notes, and most bond coupons. Formula: I = P × r × t. Compare with our Compound Interest Calculator to see the difference.
Examples
$10,000 at 5% for 3 yearsInterest $1,500 · Total $11,500$1,000 face, 4.5%/yr$45 annual coupon · $450 over 10 yearsFrequently asked questions
Simple vs compound?
Simple: only on principal. Compound: also earns interest on interest. Over decades the difference is massive.
When is simple used?
Personal loans, auto loans, short-term notes, bond coupons. Mortgages, credit cards, savings compound.
About this calculator
Simple Interest Calculator runs entirely in your browser using standard formulas. No data is sent to any server. We don't share your inputs with lenders, brokers, or anyone else — there's no funnel and no follow-up email.
Related tools
- 📈 Compound Interest Calculator — Future value with compound interest. Configurable contribution & compounding frequency.
- 💳 Loan Amortization — Monthly payment, total interest, and full payment schedule for any loan.
- 🎯 Savings Goal Calculator — How long to reach a target? Or how much to save monthly?
Why this calculator
vs typical free finance-calculator sites
| RichCalcs | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for full results) |
| Ads inside the calculator | No | Yes (banner + sidebar) |
| Lead capture (email / phone) | No | Yes — sold to lenders |
| Data sent to server | No (browser-only) | Yes (analytics + tracking) |
| Amortization schedule | Full table | Often summary only |
| Bookmarkable URL per calc | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Open source | Yes | No |