The Savings Goal Calculator estimates a simple monthly savings plan. Enter a starting balance, target amount, stated annual rate, and either a monthly contribution or a target number of months. It then estimates when the balance first reaches the target, or the fixed contribution needed for the selected timeline.
All calculations run locally in your browser. Use one currency consistently: the formulas work the same for dollars, pounds, euros, or another currency, but the page does not convert currencies.
How to use the calculator
- Enter the amount already saved in Starting balance.
- Enter the balance you want to reach in Target amount.
- Enter a non-negative Annual interest rate (%). The page converts this stated annual rate to a monthly rate by dividing by 12.
- Choose a question:
- Time needed from my monthly contribution: enter the amount added at the end of every month.
- Monthly contribution for my target time: enter a whole number of months from 1 to 1,200.
- Read the estimated time or contribution, ending value, total deposited, and estimated interest. Change one input at a time to compare plans.
The result is an educational projection, not an account quote or a promise of returns. Inputs are never uploaded by this tool.
Formula and assumptions
Let P be the starting balance, C the end-of-month contribution, r the monthly rate, and N the number of months. The modeled future value is:
Future value = P × (1 + r)^N + C × [((1 + r)^N − 1) ÷ r]
When the rate is zero, the contribution part becomes C × N. The calculator uses the same ordinary-annuity assumption as the compound interest calculator: contributions arrive at the end of each month, so a new contribution starts earning modeled interest in the following month.
To estimate time, the page solves the formula and rounds up to the first whole month whose modeled ending balance meets or exceeds the target. To estimate a required monthly contribution, it rearranges the same formula for C. The displayed money values are rounded to cents.
Example: saving 300 each month
Start with 1,000, aim for 10,000, add 300 at each month-end, and use a 4.5% stated annual rate. The monthly rate is 0.045 ÷ 12 = 0.00375. Under that fixed-rate model, the tool estimates the first month in which the balance reaches the goal, then reports the projected balance, deposits, and interest at that whole-month point.
Try the same goal at a 0% rate to separate the effect of regular deposits from the rate assumption. A percentage calculator can help you compare a proposed contribution with your current monthly savings amount.
What this calculator does not model
This page intentionally keeps the model narrow. It does not model variable APYs, daily balance methods, compounding conventions different from monthly, account minimums, fees, taxes, inflation, withdrawals, deposits made at the beginning of a month, or investment losses. If the account rate changes, rerun the estimate with an updated rate rather than treating this output as a schedule.
For growth from an initial investment with different compounding frequencies and contributions per period, use the compound interest calculator. To measure a return after you already know beginning and ending values, use the ROI calculator. For a borrowing payment and amortization schedule, use the loan calculator instead.
The U.S. SEC's Investor.gov compound interest calculator likewise identifies initial investment, monthly contribution, time, rate, and compounding frequency as planning inputs. Account disclosures and statements are the authority for an actual product's rate and crediting rules.