How this savings goal calculator works
Reaching a savings goal comes down to two forces working together: the money you set aside each month, and the interest your balance earns along the way. Saving consistently is what you control — even a modest, automatic monthly transfer adds up faster than waiting to deposit a lump sum "someday." Interest then quietly chips in on top, so the longer your time horizon, the less of the goal you have to fund yourself.
To find the required contribution, we take the standard future-value-of-an-annuity equation and solve it for the payment. Your current savings grow on their own to current × (1 + r)n, and the gap between that and your goal has to be filled by the monthly contributions plus their interest:
where C = monthly contribution, r = annual rate ÷ 12, and n = years × 12. If your current savings already grow past the goal on their own, the required contribution is zero.
The full derivation and assumptions are on our methodology page. Interest is assumed to compound monthly and rates are not guaranteed, so treat this as a planning estimate, not financial advice.
Frequently asked questions
- How much should I save each month to reach my goal?
- It depends on how far you are from the goal, how long you have and the interest you'll earn. This tool solves the annuity formula for the payment — the fixed monthly amount that, with your current savings and interest, lands exactly on your goal by the target date.
- What interest rate should I assume?
- For a short-term goal kept in a high-yield savings account or money-market fund, use today's APY — often around 4%. Longer goals invested in the market might earn more, but returns aren't guaranteed, so a conservative rate keeps your plan realistic.
- Does this store my numbers?
- No. Everything runs in your browser. Nothing you type is uploaded or saved on a server.