Savings Projection Calculator: Savings Goal, Interest and Investing

It steps through your plan one month at a time. Each month your cash earns interest on what it held at the start of the month, your take-home pay less your spending is added, any one-off event for that month is applied, and (if you invest) a fixed amount moves from cash into investments, never taking your cash below the amount you keep back. Pay and spending step up by your chosen rates after each twelve months.

A worked example: you have $20,000 now, take home $4,500 a month and spend $3,000, so you save $1,500 a month. Earning 3% a year on cash, you have $78,312 after three years: $74,000 is what you put in and $4,312 is interest. That matches the standard formula for a regular saving with interest on the opening balance each month.

Enter a goal and the calculator finds the first month your cash plus investments reach it, even when that is beyond the projection. Starting from $20,000 with a goal of $50,000 and 3% interest on cash, with no pay rises, the time depends mostly on what you save each month:

The biggest lever is the monthly amount, not the interest rate: doubling what you save from $1,000 to $2,000 a month cuts the time to the goal by about half.

Yes. Most interest you receive, or that is credited to an account you can withdraw from without penalty, is taxable income in the year it becomes available to you, whether or not you get a Form 1099-INT (IRS Topic No. 403). Enter your federal plus state marginal rate in “Tax rate on that interest” and the calculator takes it off each month as the interest is credited. In the example above, a 24% rate takes $1,026 of tax out of the $4,312 of interest over three years and leaves $77,249. The tax is really paid with your return, not out of the account each month, so this is a simplification that slightly understates the interest you would earn. Leave the rate at 0 to ignore it; qualified withdrawals from a Roth IRA, for example, are not taxed (IRS Publication 590-A).

Tick “I invest part of my savings” and set a monthly amount. That amount moves from cash into investments each month (only while you have the cash), and the projection shows a downside, an expected and an upside case so you can see the spread, not just one number. Returns are your assumptions, not forecasts, and fees come off the return. In the same plan as above, investing $1,000 of the $1,500 you save each month for three years, with 0.2% a year in fees, ends at:

At 0% a year, investing ends $1,725 behind cash here, because there is no gain to cover the fee and the interest the cash would have earned; at 6% it is $1,511 ahead and at 10% $3,773 ahead. Over a few years markets can fall as well as rise, which is why a short projection should lean on the downside case, and why the calculator lets you keep a cash buffer before anything is invested. No tax is taken off investment returns; for money in a taxable account enter a return after tax.

Use the rate your own account actually pays (the annual percentage yield, APY) and update it when it changes; this calculator does not assume today's market rates, and bank rates move. The interest is treated as credited monthly on the balance at the start of the month. For a longer horizon, remember that a rate on cash may not keep up with inflation: the result is also shown in today's dollars using the inflation rate under “More assumptions”, which is your assumption.

This is a short-term cash view: your take-home pay, your spending and the savings that build up, for one to ten years, with an optional investing pot. It deliberately ignores your home, retirement accounts and Social Security. The net worth forecast calculator follows the whole balance sheet for decades, including a home with a mortgage, 401(k) and IRA contributions and retirement withdrawals with tax; use that for the long road and this one for the next few years, such as a down payment, a wedding or an emergency fund (see the emergency fund calculator).

Irregular income, a job change or a gap between jobs, bank fees, interest rates that change, tax on investment returns, state rules beyond the take-home estimate, the timing of a bonus within the year, and any borrowing: if your savings run out the balance simply goes negative with no interest charged. The take-home estimate from a salary uses the same 2026 federal, Social Security, Medicare and state estimate as the Paycheck Calculator, with the standard deduction and wages as the only income, so it can differ from your actual pay stub. Events after the end of the projection are ignored. It is an estimate from your assumptions, not a prediction.