Calculadora de interés compuesto: proyecta crecimiento con aportes mensuales y capitalización elegida.
El interés compuesto reinvierte ganancias. Ej.: 10.000 € al 7% anual ≈ 76.123 € en 30 años sin aportes; 500 €/mes al 7% ≈ 566.764 € en 30 años.
Crecimiento con aportes mensuales
El interés compuesto recalcula sobre principal más intereses acumulados cada período. Aportes mensuales y años invertidos importan más que optimizar la tasa en el último año.
Capitalización mensual versus anual cambia el saldo final en la misma tasa nominal—alinee frecuencia al comparar productos.
No descuenta inflación ni impuestos en cuentas tributables—reduzca la tasa asumida para escenarios reales.
Guía, ejemplos y metodología
How to use this compound interest calculator
Enter your starting balance, optional monthly contribution, expected annual return, compounding frequency, and years invested. Results update instantly in your browser. Use monthly compounding when modeling most US brokerage or high-yield savings assumptions; use annual only if that is how your product quotes the rate.
Example (USD)
Input
Value
Result after 30 years (7% annual, monthly compound)
Starting balance
$10,000
$76,123 (no extra deposits)
Plus $500/month
Same rate
~$566,764 total
Interest earned
—
~$386,764 on top of $180,000 contributed
How we calculate
Lump-sum growth uses A = P(1 + r/n)^(nt). Each monthly contribution is compounded from its deposit date to the end of the horizon, then summed. We do not deduct taxes, fund expense ratios, or inflation unless you lower the return yourself. For purchasing-power planning, subtract an inflation assumption from your nominal return (e.g. 7% nominal minus 3% inflation ≈ 4% real).
Common mistakes
Quoting a yearly APY while the account compounds daily or monthly (understates growth).
Ignoring ongoing 401(k) or IRA fees when comparing to a headline market return.
Assuming you can keep max contributions every year without a cash-flow plan.
Comparing to a CD or Treasury without matching the same time horizon.
Monthly contributions vs lump sum (US portfolios)
Most US retirement savers compound through payroll 401(k) deferrals plus employer match. A $500/month contribution at 7% nominal over 30 years can exceed $560,000—often more impactful than optimizing a single year's return. Use this calculator to test sensitivity: raise contributions 1–2% before chasing an extra 0.5% fund return.
Real vs nominal returns
Headline market returns are nominal. If inflation averages 3% and your portfolio earns 7%, your real return is about 4%. For goals stated in today's dollars (e.g. $1M nest egg), subtract an inflation assumption from the return field or run a second scenario at a lower rate.
Who should use this calculator
Use it for HYSA projections, taxable brokerage goals, 529 planning, or back-of-envelope retirement checks. Pair with our retirement and FIRE calculators when the question is sustainable withdrawal, not just accumulation. Pair with DCA calculator when deciding whether to invest a windfall all at once or over months.
For a single deposit: A = P(1 + r/n)^(nt), where P is principal, r is the annual rate as a decimal, n is compounding periods per year, and t is years. With monthly contributions, each deposit has its own timeline; this calculator totals them.
How much does $500 a month grow in 30 years?
At about 7% average annual return with monthly compounding, $500/month for 30 years is roughly $566,764 total (about $180,000 contributed). Your starting balance and actual return change the outcome.
¿Cómo funciona el interés compuesto?
Gana intereses sobre el saldo total acumulado, no solo sobre el capital inicial — por eso la curva se acelera.
¿Cuánto generan 500 €/mes en 30 años?
Al ~7% anual, 500 €/mes durante 30 años ≈ 566.764 €. Ajuste tasa y capital inicial en la calculadora.
Empezar a los 25 vs 35: ¿cuánta diferencia hay?
Diez años extra de capitalización suelen pesar más que subir un poco la rentabilidad.