Savings withdrawal calculator
12,000 with 1,000 taken out each month at 0% lasts exactly 12 months. Add your balance, the monthly withdrawal and the interest rate, and see when the account reaches zero, or whether it never does. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Initial balance
- 12,000
- Monthly withdrawal
- 1,000
- Annual rate
- 0
- Monthly rate
- 0
- Months
- 12
- Years
- 1
- Years whole
- 1
Emergency funds, sabbatical pots, and drawdown plans all need that horizon before the first transfer is set up. This tool accepts the starting savings balance, the fixed monthly withdrawal, and the nominal annual interest rate as a percent, compounds that rate monthly, then returns the integer months until the balance is depleted. When the withdrawal is no larger than the interest the full balance earns, the account never falls and the response says so instead of inventing a fake countdown.
How long a savings balance lasts with interest and a monthly draw
A savings withdrawal schedule is the reverse of a savings plan: money leaves the account every month, while remaining principal still earns interest. Each month the balance is grown by one plus i and then reduced by the withdrawal W. When the annual rate is zero there is no growth, so the month count is simply the starting balance B divided by W, rounded up to the next whole month whenever a remainder would leave a partial last period.
When the rate is positive the closed form is n equals the natural log of W over W minus B times i, divided by the natural log of one plus i, and months is the ceiling of that n. That identity is the ordinary drawdown of a compound-interest account with level end-of-month withdrawals, the same recurrence banks use on a savings statement.
A last month that only covers a partial withdrawal still counts as one month of remaining life, because that is the month in which the account actually hits zero. The calculator does not model taxes, inflation, market returns, a changing withdrawal, or a four-percent safe-withdrawal rule. It only answers how many months this cash pile lasts under a fixed monthly draw and a stated annual rate.
What you can do with it
Emergency-fund and sabbatical drawdown
Enter the cash you have, the monthly amount you will transfer out, and the savings rate, then read months until depletion before you start the standing withdrawal.
Homework and compound-interest oracles
Students compute how long a nest egg lasts under a fixed monthly draw with monthly compounding and compare against a deterministic result that rejects a negative starting balance.
FAQ
What happens if the initial balance is negative?
A negative savings balance is not a valid starting point for a withdrawal schedule and is not billed.
Is the annual interest rate a percent or a decimal fraction?
A percent. Use 4 for four percent per year, not 0.04.
What if my withdrawal is smaller than the interest the account earns?
The balance never falls. Raise the monthly withdrawal or lower the rate to get a finite month count.
How long will my savings last with a fixed monthly withdrawal?
Each month the balance earns its interest and then your withdrawal comes out, until nothing is left. With 12,000 and 1,000 a month at 0%, the money lasts exactly 12 months.
Does a short final month count as a whole month?
Yes. If the last month only covers part of your usual withdrawal, it still counts as one month, because that is the month in which the account actually reaches zero.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/fin/savings-withdrawal \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"initial_balance":12000,"monthly_withdrawal":500,"annual_rate":4}'const res = await fetch("https://api.kit.forhosting.com/fin/savings-withdrawal", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"initial_balance": 12000,
"monthly_withdrawal": 500,
"annual_rate": 4
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fin/savings-withdrawal",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"initial_balance": 12000,
"monthly_withdrawal": 500,
"annual_rate": 4
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fin/savings-withdrawal", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"initial_balance":12000,"monthly_withdrawal":500,"annual_rate":4}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"initial_balance":12000,"monthly_withdrawal":500,"annual_rate":4}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fin/savings-withdrawal", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"initial_balance": 12000,
"monthly_withdrawal": 500,
"annual_rate": 4
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fin.savings_withdrawal",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_abs | 1000000000000000 |
max_rate | 100 |
max_months | 1000000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
A savings withdrawal calculator answers the household question that sits between a nest-egg balance and a monthly living draw: if this account starts at this amount, I take this much every month, and it still earns this annual interest, how many months until the money is gone? A negative starting balance is rejected as invalid_input rather than treated as a debt schedule. Successful calls are billed at $0.002; invalid input is not charged.
How long a savings balance lasts with interest and a monthly draw
Convert the quoted annual rate into a monthly rate i equal to annual_rate divided by one hundred and then by twelve. If W is less than or equal to B times i, the interest earned on the full starting balance already covers the draw, so the balance never falls and this calculator reports never_depletes instead of a month count. If the starting balance is already zero, months is zero and the status is already_empty.
Input contract, negative balances, and the response shape
Example: twelve thousand at a one-thousand monthly draw and a zero rate lasts exactly twelve months. POST a JSON body with three required finite numbers. initial_balance is the starting savings in currency units and must be greater than or equal to zero; aliases balance, principal, savings, and starting_balance are accepted so a brokerage export or a statement row does not need a rename step. A negative initial_balance is the hard product error: it fails with invalid_input naming the field and is not billed, because a negative savings balance is not a valid starting point for a withdrawal schedule. monthly_withdrawal is the amount taken at the end of each month in the same currency and must be strictly greater than zero; aliases withdrawal, monthly, draw, and monthly_draw are accepted. annual_rate is the nominal annual interest as a percent, compounded monthly—use 4 for four percent per year, not 0.04—and must be a finite number greater than or equal to zero and at most one hundred; aliases rate, interest_rate, annual_interest_rate, and apr are accepted. Missing fields, empty strings, non-finite values, a zero or negative withdrawal, a negative rate, or a magnitude beyond the published limits fail with invalid_input naming the problem. On success the body echoes the three inputs and monthly_rate, then either returns months, years, years_whole, and months_remainder with status finite, or omits the month fields and sets never_depletes when interest covers the draw. Prefer JSON numbers over currency-formatted strings. Pricing for a successful item is a flat $0.002.
Where a savings withdrawal calculator earns its keep
People who search savings withdrawal or how long will my savings last already know they want a month count from a nest egg, a monthly draw, and an interest rate, not a startup cash-runway ratio and not a four-percent retirement rule of thumb. An emergency-fund planner uses it before setting a standing transfer: six months of rent is a different horizon once the account still pays a small annual rate. Sabbatical and parental-leave pots, bridge cash between jobs, and drawdown of a maturing certificate into living costs all share the same three-field identity. Failed validation does not consume balance. Classroom consumer-math courses assign compound-interest drawdown worksheets and need an oracle that marks a negative starting balance as invalid_input. Automation pipelines call the same contract at $0.002 per successful item without standing up a spreadsheet service. Keep requests small, pin the integer months in tests, and you get reproducible savings-drawdown arithmetic for homework, household planners, and lightweight budgeting webhooks without standing up a full retirement engine.
Integration use cases
Budgeting scripts and household planning
Call the same contract from a planner or a webhook so a bridge-cash or certificate-drawdown horizon matches the landing-page widget down to the month.
Technical questions
How do I calculate how long my savings will last?
Send initial_balance, monthly_withdrawal, and annual_rate as a percent. The API compounds the rate monthly and returns the integer months until the balance is depleted, or reports that the account never depletes if interest covers the draw.
What does the savings withdrawal calculator cost?
The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.