Savings & Banking
Simple Interest Calculator
Simple interest is charged only on the original principal, never on interest already accrued. Enter an amount, rate, and time to see the interest and total, plus how much more compound interest would add.
Total value
$11,500
- Simple interest
- $1,500
- Principal
- $10,000
- Extra from compounding
- $115
What monthly compounding would add over simple interest.
How this calculator works
Simple interest = principal × annual rate × years; total = principal + interest, in exact cents. The 'extra from compounding' figure computes the same principal and rate with monthly compounding and shows the difference.
Real loans and accounts may compound daily or monthly and include fees — use this for a clean estimate, and see our Compound Interest calculator for growth that compounds.
Try an example
Frequently asked questions
How do you calculate simple interest?
Multiply the principal by the annual rate and the number of years: interest = principal × rate × time. $10,000 at 5% for 3 years earns $10,000 × 0.05 × 3 = $1,500, for an $11,500 total. Unlike compound interest, it never charges interest on interest.
What's the difference between simple and compound interest?
Simple interest is figured only on the original principal, so it grows in a straight line. Compound interest is figured on the principal plus all prior interest, so it accelerates. Over long periods the gap is large — compounding is why savings grow and why credit-card debt spirals.
What uses simple interest?
Many auto loans and some personal loans, along with most short-term promissory notes. For borrowers, simple interest is favorable — paying early reduces the principal that interest is charged on. Savings and investments, by contrast, benefit from compounding.
Related calculators
Compound Interest Calculator
See how your savings grow with compound interest and monthly contributions — final balance, interest earned, and a year-by-year growth table.
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Watch your savings account grow: enter your balance, monthly deposit, and APY to see the future value and every dollar of interest along the way.
Loan Calculator
Calculate the monthly payment, total interest, and payoff date for any personal, auto, or fixed-rate loan — and see how extra payments shorten it.
Disclaimer: DayCents provides this calculator for educational purposes only. Results are estimates based on your inputs and the stated assumptions — they are not financial advice, a quote, or an offer of credit. Consult a qualified financial professional before making major money decisions.