Savings Goal Calculator
Work backward from a savings target to the monthly contribution that gets you there by your deadline.
What this is solving for
Most calculators ask: if I save X per month, how much will I have in Y years? This one asks the opposite, which is usually the more useful question: if I need X dollars by Y years from now, how much do I have to save per month to get there? It solves the compound-interest formula for the monthly payment instead of the final balance.
How the math runs
We use monthly compounding with contributions treated as an ordinary annuity — payment at the end of each month. Your current savings grows at the same rate without any additional input from you; the required monthly contribution is whatever additional amount closes the gap between that growth and your target. If your current savings alone would already beat the target at the given rate, the required contribution drops to $0 and the verdict changes accordingly.
Where this breaks down
Real returns aren't constant. Inflation erodes the target. Tax treatment of growth depends on account type (Roth, traditional, taxable). Most importantly: for short horizons — anything under about 5 years — the return assumption matters less than your ability to contribute consistently. Budget first, optimize return second.