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mQuickCalc
📈
Estimates only. Results assume a fixed interest rate for the full period. Real investments vary year to year. Use this for fixed-rate planning (CDs, bonds, HYSA) or for rough long-term stock-market estimates.

Compound Interest Calculator — Final Amount & APY

See how a single deposit grows with compound interest. Pick how often the interest compounds — daily for crypto/stocks, monthly for HYSAs, quarterly for bonds.

$0.00
total portfolio
Future Value
—
Total contributions
—
Interest earned
—

Monthly contributions dramatically increase final value. $500/month at 8% for 20 years = $298K in contributions, $298K in interest.

Monthly contributions dramatically increase final value. $500/month at 8% for 20 years = $298K in contributions, $298K in interest.

How compounding frequency matters

A 5% rate compounded daily yields 5.1267% APY; compounded monthly it is 5.116%; annually, 5.0%. The difference is small at low rates, but at 20% or higher, daily compounding can add 0.5-1% extra per year. For practical purposes, monthly is the right default for most savings accounts.

How this calculator works

The eighth wonder of the world

Einstein may or may not have called compound interest "the eighth wonder of the world," but the mathematics is real: small regular contributions and long time horizons produce extraordinary results. Start at 25 vs 35 vs 45 creates vastly different retirement outcomes.

mQuickCalc
📈
Estimates only. Results assume a fixed interest rate for the full period. Real investments vary year to year. Use this for fixed-rate planning (CDs, bonds, HYSA) or for rough long-term stock-market estimates.

Compound Interest Calculator — Final Amount & APY

See how a single deposit grows with compound interest. Pick how often the interest compounds — daily for crypto/stocks, monthly for HYSAs, quarterly for bonds.

$0.00
total portfolio
Future Value
—
Total contributions
—
Interest earned
—

Monthly contributions dramatically increase final value. $500/month at 8% for 20 years = $298K in contributions, $298K in interest.

Monthly contributions dramatically increase final value. $500/month at 8% for 20 years = $298K in contributions, $298K in interest.

How compounding frequency matters

A 5% rate compounded daily yields 5.1267% APY; compounded monthly it is 5.116%; annually, 5.0%. The difference is small at low rates, but at 20% or higher, daily compounding can add 0.5-1% extra per year. For practical purposes, monthly is the right default for most savings accounts.

How this calculator works

The eighth wonder of the world

Einstein may or may not have called compound interest "the eighth wonder of the world," but the mathematics is real: small regular contributions and long time horizons produce extraordinary results. Start at 25 vs 35 vs 45 creates vastly different retirement outcomes.

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