Compound Interest Calculator
Compare simple vs compound growth with adjustable compounding frequency and contributions.
Investment details
Future value (compound)
Interest earned: $10,097
Simple interest would yield $17,000 — compound earns $3,097 more
Future value
+$10,097 interest
Simple vs compound growth
Estimates only. Actual returns vary. Not financial advice.
Future value
$20,097
+$10,097 interest
How it works
Compound interest means you earn returns on both your original principal and on interest that has already been credited. Over multi-year horizons, that snowball effect is usually far larger than simple interest on the same starting amount.
Enter a starting balance, annual rate, and time horizon, then choose how often interest is compounded (for example yearly, monthly, or daily). More frequent compounding slightly increases effective growth for the same nominal rate.
The calculator contrasts a simple-interest path with a compound path so you can see the gap widen over time. That gap is the practical reason long-term savers care about compounding frequency and staying invested.
Use the tool to stress-test “what if I wait five more years?” or “what if my rate is 1% lower?” Educational estimates help compare scenarios; they are not a forecast of any specific account or market.
For contributions over time, pair this page with the Investment Calculator. Compound interest here focuses on growth of a balance; investment mode adds recurring deposits and solve-for options.
Frequently asked questions
- What is the difference between simple and compound interest?
- Simple interest is calculated only on the original principal. Compound interest is calculated on principal plus accumulated interest, so earnings can grow faster as the balance rises.
- Does compounding frequency matter much?
- Yes, but usually modestly at everyday rates. Monthly vs annual compounding changes effective yield; the bigger levers are rate, time, and how much you contribute.
- Is the rate I enter before or after fees and taxes?
- Enter whatever return you want to model. For planning, many people use an after-fee or after-tax estimate so the projection is closer to spendable growth.
- Can this replace a bank or brokerage statement?
- No. Statements reflect your real product rules, day-count conventions, and fees. Treat Calcuit results as teaching estimates for comparing scenarios.
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