Retirement Compound Interest Calculator
See how compound interest supercharges retirement savings with our free calculator. Time is the most powerful factor in building wealth—starting early and letting compound interest work over decades can turn modest contributions into substantial nest eggs.
The Power of Time: Starting Age Comparison
| Starting Age | Monthly Contribution | At Age 65 (7% return) | Total Contributed | Interest Earned |
|---|---|---|---|---|
| 25 | $500 | $1,199,175 | $240,000 | $959,175 |
| 30 | $500 | $829,421 | $210,000 | $619,421 |
| 35 | $500 | $566,765 | $180,000 | $386,765 |
| 40 | $500 | $379,494 | $150,000 | $229,494 |
| 45 | $500 | $246,197 | $120,000 | $126,197 |
Retirement Account Tax Advantages
Account type significantly impacts compound growth:
| Account | Tax Benefit | 2024 Contribution Limit | Best For |
|---|---|---|---|
| 401(k) | Pre-tax contributions, tax-deferred growth | $23,000 (+$7,500 catch-up) | Employer match |
| Traditional IRA | Tax-deductible, tax-deferred growth | $7,000 (+$1,000 catch-up) | Tax deduction now |
| Roth IRA | After-tax, tax-free growth | $7,000 (+$1,000 catch-up) | Tax-free in retirement |
Retirement Growth Calculator
``javascript
function calculateRetirementGrowth(currentAge, retirementAge, monthlyContribution, annualReturn, currentBalance = 0) {
const yearsToRetirement = retirementAge - currentAge;
const months = yearsToRetirement * 12;
const monthlyRate = annualReturn / 100 / 12;
let balance = currentBalance;
for (let m = 0; m < months; m++) {
balance = (balance + monthlyContribution) * (1 + monthlyRate);
}
const totalContributions = currentBalance + (monthlyContribution * months);
const compoundGrowth = balance - totalContributions;
const percentFromCompounding = (compoundGrowth / balance * 100);
return {
projectedBalance: balance.toFixed(2),
totalContributions: totalContributions.toFixed(2),
interestEarned: compoundGrowth.toFixed(2),
percentFromCompounding: percentFromCompounding.toFixed(1) + '%'
};
}
``
The 4% Rule for Retirement Income
Financial planners often use the 4% rule: withdraw 4% of your portfolio annually in retirement. With $1 million saved, that's $40,000/year. To replace $80,000 in annual income, target $2 million in retirement savings.