Compound interest is interest on your interest — the reason small, steady saving beats big, late saving. Enter a starting amount, a monthly habit, and a rate, and watch what time does with it.
Future value
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Total you put in
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Interest earned
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Assumes a steady rate with no taxes, fees, or withdrawals. Real savings rates change and real investments fluctuate. Educational content only — not individualized financial, tax, or investment advice.
The rule of 72
Quick mental shortcut: divide 72 by your annual rate to estimate how many years it takes money to double. At 6%, that’s about 12 years. At 9%, about 8. It’s an estimate, not exact — but it makes the power of a few extra points of return very real, very fast.