What is "Compound Interest"?

Compound interest is when interest is calculated on both the initial principal and the accumulated interest from previous periods. This 'interest on interest' causes exponential growth over time. Albert Einstein reportedly called it the 'eighth wonder of the world' due to its powerful wealth-building effect.

Example: $10,000 at 7% compound interest for 30 years → $76,000 (7.6x the principal)

Calculadora de Interés Compuesto

0%10%20%
1y25y50y
Used for the "this year vs last year" simulation.
Total Invertido
105.000,00 €
Interés Total Ganado
+139.719,00 €
Monto Final
244.719,00 €

Gráfico de Crecimiento

You vs Average

Benchmark: U.S. long-term average return assumed at 7%

Final gap: +0,00 €

This Year vs Last Year

Compares one-year outcomes using current and last-year return assumptions.

End-of-year difference: +119,00 €
💰

Compound Interest Result

244.719,00 €

Estimated interest: 139.719,00 €

Expected value after 20 years (7% annual return)

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¿Qué es el Interés Compuesto?

El interés compuesto es el interés calculado sobre el principal inicial y el interés acumulado de períodos anteriores. A diferencia del interés simple, que se calcula solo sobre el monto principal, el interés compuesto permite que tu dinero crezca más rápido con el tiempo.

La Fórmula del Interés Compuesto

A = P(1 + r/n)nt

A = P(1 + r/n)^(nt) donde A es el monto final, P es el principal, r es la tasa de interés anual, n es el número de veces que se capitaliza el interés por año, y t es el tiempo en años.

La Regla del 72

La Regla del 72 es una forma simple de estimar cuánto tiempo tardará una inversión en duplicarse. Divide 72 por tu tasa de retorno anual para obtener el número aproximado de años. Por ejemplo, con un retorno anual del 6%, tu inversión se duplicará en aproximadamente 72÷6=12 años.

At 7% return, your investment doubles in about 10.3 years.

How to Read the Comparison Features

  • "You vs Average": See whether your assumptions outperform or underperform a U.S. long-term baseline.
  • "This Year vs Last Year": Quantify how a rate change shifts your one-year ending value under the same contribution plan.
  • Rate and term sliders update charts in real time so you can test scenarios quickly.

Consejos de Interés Compuesto

  • Comienza a invertir temprano para maximizar el crecimiento compuesto
  • Realiza contribuciones regulares, incluso las pequeñas cantidades se suman
  • Reinvierte tus ganancias para acelerar el crecimiento
  • Piensa a largo plazo para obtener los mejores resultados
Last updated: 2025-01

📝 How to Use

1

Enter Initial Investment

Input your starting principal amount.

💡 Starting small is okay - consistency matters!

2

Set Annual Return Rate

Enter expected annual return rate (%).

💡 Stock funds average 7-10%, savings 2-4%.

3

Choose Investment Period

Enter how many years you plan to invest.

💡 Compound effect accelerates after 10 years!

4

Add Monthly Deposits (Optional)

If you plan to add money monthly, enter the amount.

💡 Regular contributions maximize compound growth.

🎯 Who is this for?

Useful for various situations

👶

College Fund for Kids

Start when your child is born to comfortably cover tuition costs.

Long-termEducation
🏠

Down Payment Savings

Calculate how long it takes to save for your dream home.

HomeSavings
🧓

Retirement Planning

Starting in your 30s makes comfortable retirement possible.

PensionRetirement
💎

Investment Simulation

Compare expected returns from ETFs, funds, and savings accounts.

ComparisonETF
💡

Expert Tip

The key to compound interest is 'time'. If you start investing $300/month at 30, someone starting at 40 can't catch up even with $1,000/month. The best time to invest was 10 years ago. The second best time is now.

Warren Buffett's Investment Philosophy

❓ Frequently Asked Questions

How do I use the compound interest calculator?

Just enter your initial investment, annual return rate, and investment period. Optionally, you can add monthly contributions. The calculator shows your final amount, total interest, and yearly growth chart.

💡 Adding monthly deposits supercharges your compound growth!

What is the Rule of 72?

Divide 72 by your annual return rate to estimate how long it takes to double your money. For example, at 8% return: 72÷8=9 years to double your investment.

💡 Our calculator automatically shows you the Rule of 72 result!

What is the difference between simple and compound interest?

Simple interest applies only to principal, while compound interest applies to principal + accumulated interest. $10,000 at 5% for 20 years: simple interest = $20,000, compound = $26,500. The longer you invest, the bigger the difference.

💡 This is why compound interest is called "interest on interest"!

What is a realistic annual return rate?

It varies by investment: Savings 2-4%, Bonds 3-5%, Stock ETFs 7-10%, Individual stocks vary widely. For long-term planning, 7% is a conservative and realistic estimate.

💡 Remember: higher returns usually mean higher risk!

How early should I start investing?

The earlier, the better! Starting at 25 with $200/month at 7% gives you ~$550,000 by 65. Starting at 35 with the same amount yields only ~$250,000. A 10-year difference makes more than 2x difference!

📌 Key Takeaways

  • Time is the most important factor in compound interest. Start early!
  • 📐Rule of 72: 72÷rate = years to double your money
  • 📈Monthly contributions maximize compound growth.
  • 🚀Long-term investing (10+ years) unlocks explosive compound growth.

📚 Guía local de cálculo

Lógica de fórmula

Se aplican fórmulas públicas de finanzas, préstamos, ratios y conversión.

Alcance de fuentes

Tomamos como referencia estándares públicos y prácticas habituales por país.

Supuestos

Impuestos, comisiones, tasas y límites cambian según región e institución.

Result Interpretation

Usa este resultado como escenario base. Antes de decidir, compáralo con oferta real y fiscalidad local.

Configuración local

Moneda: EUR

Unidades: metric

Modelo fiscal: US payroll estimate

Aviso normativo

Esta herramienta usa valores locales para estimación. Las condiciones reales y límites legales dependen de la entidad y del país.

Acciones recomendadas

  • Compara al menos 2-3 entidades locales antes de contratar.
  • Verifica por escrito comisiones, impuestos y cláusulas de prepago.
  • Simula un escenario de estrés con +1-2% de interés.

Antes de decidir, verifica las reglas actualizadas de la entidad local.

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