Compound interest & FIRE calculator

Project savings growth with monthly contributions, inflation adjustment, and a year-by-year chart. Plus a FIRE target check so you can see exactly when you'd hit financial independence.

Your plan

Inflation & FIRE target

Rule of thumb: 25× your annual expenses

Future corpus

Projected corpus
Total contributed
your money in
Interest earned
compounding growth
Real value
today's purchasing power
Multiplier
× of contributions

Growth over time

Contributed Total corpus FIRE target

Time is the lever

Starting at 25 vs 35 with the same monthly contribution and rate can double your final corpus. The first 10 years of compounding does most of the work in the back end. Start early, even small.

The 4% rule (FIRE)

Once your portfolio equals 25× annual expenses, you can typically withdraw 4% per year indefinitely. So if you spend $50K/year, FIRE = $1.25M. This calculator's default target.

Nominal vs real returns

A 7% nominal return at 3% inflation = ~4% real return. Always check the real-value display — that's what your corpus actually buys. Long-term planners use 5–7% real for diversified equity.

About compound interest & FIRE

How does compound interest work?

Compound interest means your returns themselves earn returns. If you have $10,000 at 7% annual interest, year one gives $700. Year two earns 7% on $10,700, not just $10,000 — $749. Over 30 years, compounding adds ~$70,000 on top of the simple-interest result. The formula: FV = P × (1 + r/n)n×t, where n is the compounding frequency per year.

What is FIRE?

FIRE stands for Financial Independence, Retire Early. The traditional rule of thumb: you reach FIRE when your invested assets equal 25× your annual expenses (the "4% rule"). At that point, you can withdraw 4% per year indefinitely without depleting principal. So if you spend $50,000/year, your FIRE number is $1.25M.

Should I adjust for inflation?

Yes — especially for long-horizon planning. Inflation averages 2–3% in developed economies, 5–7% in emerging markets. A nominal $1M in 30 years at 3% inflation is worth only about $412K in today's purchasing power. The real-value display shows what your corpus can actually buy in present-day terms — that's the number that matters.

What return rate should I assume?

Historical long-term returns: US S&P 500 ~7–10% real, global equity ~5–7% real, bonds ~2–4%, cash ~0–1%. For long-term retirement planning, 6–8% nominal is a reasonable mid-range assumption. Be conservative — projecting 12% and getting 6% means hitting your goal a decade late.

Lump sum or monthly contributions?

Mathematically, lump sum almost always wins if the market trends upward — more capital compounding for longer. But most people don't have a lump sum, and monthly contributions (dollar-cost averaging) work better psychologically through downturns. The best portfolio is the one you actually keep contributing to.

Is my data stored anywhere?

No. This calculator runs entirely in your browser. None of your financial data is sent to any server.

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