Find out how long your savings will last, solve for a sustainable withdrawal amount, and compare depletion timelines
| Years savings last | Category | What it means |
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| Withdrawal per period | Annual amount | Years lasting | Depletion year | Interest earned |
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| Metric | Value | Notes |
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Founder & CEO, Toolraxy
Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
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The math behind spending down savings looks simple, but small changes shift the answer by years. A 4% return instead of 3% can add five years of runway. A monthly withdrawal instead of quarterly changes the depletion date by months. An inflation adjustment, even a small one, compounds against you.
This calculator handles the full picture. It runs a year-by-year simulation that credits interest at your chosen compounding frequency and debits withdrawals at your chosen frequency. Two frequencies aren’t always the same. Interest can compound monthly while withdrawals happen quarterly, and the simulation accounts for that. The reverse-solve mode answers a more practical question: what withdrawal amount is actually sustainable for the length of time you need?
Pick your currency. Every money field follows the symbol you pick.
Enter the starting savings balance. This is your investable amount today, whether it’s in a savings account, brokerage, or a mix.
Set the annual interest or return rate. Use 4% for a conservative bond-heavy portfolio, 6% to 7% for a balanced one. Negative rates model idle cash losing ground to inflation.
Choose a compounding frequency. Monthly is the most common for savings accounts, daily for money market accounts.
Enter the withdrawal amount per period. The dollar figure you plan to pull out each time.
Set the withdrawal frequency. This can differ from the compounding frequency, and the simulation handles both.
Pick the timing. Beginning-of-period withdrawals are taken before interest; end-of-period comes after.
Add an annual increase if you want inflation-adjusted withdrawals. Set it to your expected inflation rate to preserve real purchasing power.
The core simulation subtracts each withdrawal and credits interest at the compounding frequency you chose.
Formula: Balance (Period N) = (Balance (Period N−1) − Withdrawal) × (1 + Periodic Rate)
The periodic rate is the annual rate divided by the compounding frequency. If the annual rate is 4% and compounding is monthly, the periodic rate is 0.333% per period. Interest accrues every period whether or not a withdrawal happens that period.
For beginning-of-period timing, the withdrawal comes out first, then interest is credited on the reduced balance.
Formula: Balance (Period N) = (Balance (Period N−1) − Withdrawal) × (1 + Periodic Rate) [beginning]
For end-of-period timing, interest is credited first, then the withdrawal comes out.
Formula: Balance (Period N) = Balance (Period N−1) × (1 + Periodic Rate) − Withdrawal [end]
The reverse-solve mode uses the closed-form present value of an annuity formula.
Formula: Sustainable Withdrawal = Balance ÷ [(1 − (1 + i)^−N) ÷ i]
Here i is the periodic rate and N is the total number of withdrawal periods. This is the amount that exactly depletes the balance in the target duration.
If you enter an annual increase, each year’s withdrawal grows by that percentage. This models inflation-adjusted spending.
Formula: Withdrawal (Year N) = Withdrawal (Year N−1) × (1 + Annual Increase)
You’re 58 with $340,000 in a balanced portfolio earning 4.2% annually, compounded monthly. You plan to withdraw $1,850 a month, taken at the end of each period, with no annual increase. Your projection horizon is 40 years.
Step 1: Annual withdrawal = $1,850 × 12 = $22,200.
Step 2: Withdrawal rate = $22,200 ÷ $340,000 = 6.53%.
Step 3: Run the simulation. At a 4.2% return with monthly compounding, the portfolio depletes in year 21, at age 79. Not enough.
Step 4: Switch to reverse-solve mode with a 30-year target. The sustainable monthly withdrawal comes out to $1,590. That’s $260 less per month than the original plan.
Step 5: Add a 2% annual increase to model inflation. The depletion year shifts from 21 to 18. The increase accelerates the drawdown by three years.
Step 6: Reduce the withdrawal to $1,500 a month and keep the annual increase. Now the portfolio survives the full 30-year target with a small buffer.
At a $25,000 annual withdrawal and 4% returns with monthly compounding, about 30 years. At $40,000 a year, roughly 17 years. At $50,000 a year, about 13 years. The calculator gives you the exact figure for your own numbers.
For a 30-year horizon with a balanced portfolio, 3.5% to 4% has historically been safe. For savings accounts earning 4%, a 5% to 6% withdrawal rate can work if you’re willing to deplete the balance. The reverse-solve mode computes the exact amount for your target duration.
More frequent compounding credits slightly more interest over time. At 4% annually, monthly compounding produces an effective rate of 4.07% and daily compounding produces 4.08%. The difference is small but adds up over decades.
Yes, slightly. Beginning-of-period withdrawals reduce the balance before interest is credited, which cuts a small amount from each period’s earnings. Over a 30-year horizon, the difference is usually a few months of runway compared to end-of-period withdrawals.
Enter an annual increase equal to your expected inflation rate. A 2.5% increase keeps purchasing power roughly flat. A 3% increase actually improves real purchasing power. Any increase accelerates depletion, so the balance has to earn enough to cover both the withdrawal and the increase.
Use the actual APY the account pays. High-yield savings accounts currently pay 4% to 5%. Regular savings accounts pay less than 1%. CDs lock in a fixed rate for a term. The calculator’s return input is the annual rate you expect to earn, before tax.
The balance shrinks. If the withdrawal exceeds interest every year, the money will eventually run out. The question is only when. The simulation shows the year-by-year path so you can see the depletion point.
Monthly withdrawals smooth out cash flow and are easier to budget around. Quarterly withdrawals mean larger individual transactions, which some people prefer for simplicity. The total annual withdrawal is the same either way, but the timing affects how much interest the balance earns between withdrawals.
Use the reverse-solve mode. Enter a target duration, and the calculator returns the withdrawal amount that exactly depletes the balance in that many years. The formula is PMT = PV × r ÷ (1 − (1 + r)^−N), where r is the periodic rate and N is the total number of withdrawal periods.
Yes. Replace the return rate with the expected revenue or cash generation, and the withdrawal amount with the monthly spend. The math is identical. The tool doesn’t care whether the money came from a retirement account or a project budget.
The simulation runs with a negative rate, which means the balance loses value to inflation or fees even before withdrawals come out. Negative rates model idle cash, high-fee accounts, or deflation-adjusted values. The balance depletes faster than with a positive rate.
No. All figures are pre-tax. Withdrawals from a traditional IRA or 401(k) are taxed as ordinary income, which reduces the amount you actually have available to spend. Enter a net withdrawal amount (after tax) to model the after-tax effect.
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