Cash runway calculator
With 120,000 in the bank and a monthly net burn of 15,000, you have 8 months of runway, about 243.5 days. Enter your cash and monthly burn to see how long it lasts at today's pace. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Cash balance
- 120,000
- Monthly net burn
- 15,000
- Runway months
- 8
- Runway days
- 243.5
- Runway years
- 0.6666666667
- Status
- finite
Cash runway is the number of months a company, project, or household can keep operating before the bank balance hits zero at the current burn rate. Founders, finance leads, and freelancers track it weekly when fundraising, cutting costs, or deciding how long a product launch can afford to lose money. This cash runway calculator takes two numbers you already know—current cash balance and monthly net burn—and returns months, approximate days, and years of runway with a clear status when burn is zero or negative. The math is the same simple division used in board decks and investor updates: runway equals cash divided by monthly net burn.
When knowing your runway helps you decide
Startup operators use a cash runway calculator before every board meeting and fundraise to turn bank and burn figures into a shared months-left number everyone can debate. Fractional CFOs and bookkeeping tools embed the same formula so clients see runway update when payroll or SaaS spend changes, without standing up a full FP&A engine. Product and engineering orgs track runway as a go or no-go gate for hiring freezes, infra spend, and experiment budgets when the company is pre-profit.
Household and creator-economy users apply the same two inputs—checking account plus average monthly deficit—to plan how long a career break or product build can last. Pair it with expense or revenue tools when you need burn derived from line items, then feed the net burn here for the final runway estimate.
What you can do with it
Board and investor updates
Convert current cash and monthly net burn into months, days, and years of runway for board decks and monthly investor notes.
Hiring and spend gates
Recompute runway after planned headcount or vendor spend so ops teams know how many months remain before cash-out.
FAQ
What if monthly net burn is zero or negative?
Status is infinite and infinite is true: you are not consuming cash at a steady rate (break-even or profitable). Duration fields are omitted rather than returned as null.
How many months of runway do 120,000 and a 15,000 burn give?
Eight months, because 120,000 divided by 15,000 is 8. That is about 243.5 days, or two thirds of a year, provided spending and income stay at today's pace.
What counts as monthly net burn?
The cash that leaves each month minus the cash that comes in, usually operating expenses minus cash revenue. Leave out one-time financing such as a new loan or investment round, so the figure reflects normal operations.
What happens when the cash balance is already zero?
If the balance is zero and you are still burning cash, the result shows the runway as exhausted, with zero months left, so it works as a red flag instead of an empty answer.
Does the runway account for future growth or new revenue?
No. It assumes today's pace continues, with no growth model, revenue forecast or random scenarios. When your burn is about to change, for example after new hires, run it again with the new figure.
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/finance/cash-runway \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"cash_balance":120000,"monthly_net_burn":15000}'const res = await fetch("https://api.kit.forhosting.com/finance/cash-runway", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"cash_balance": 120000,
"monthly_net_burn": 15000
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/finance/cash-runway",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"cash_balance": 120000,
"monthly_net_burn": 15000
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/finance/cash-runway", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"cash_balance":120000,"monthly_net_burn":15000}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"cash_balance":120000,"monthly_net_burn":15000}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/finance/cash-runway", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"cash_balance": 120000,
"monthly_net_burn": 15000
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "finance.cash_runway",
"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.
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
There is no growth model, no revenue forecast, and no Monte Carlo noise—just a deterministic parse endpoint you can embed in dashboards, spreadsheets, and internal tools at the published $0.002 API price.
What cash runway means and how the formula works
Cash runway answers a single operational question: if cash inflows and outflows stay near today’s pace, how long until the balance is gone? Monthly net burn is the typical cash leaving the business each month after cash coming in—often monthly operating expenses minus monthly cash revenue, excluding one-time financing. For example, one hundred twenty thousand dollars of cash and a fifteen thousand dollar monthly burn yield exactly eight months of runway; the same cash with a ten thousand dollar burn yields twelve months. When that net figure is positive, the company is consuming cash and runway in months is cash_balance divided by monthly_net_burn. The calculator also reports runway_days using the mean Gregorian month length of three hundred sixty-five point two five days per year divided by twelve, and runway_years as months divided by twelve, so product, hiring, and fundraising calendars can share one consistent clock. When cash is already zero and burn is still positive, status is exhausted and runway_months is zero—useful for red-flag alerts rather than a silent empty response.
Inputs, validation, and the infinite-burn edge case
Monthly net burn may be positive, zero, or negative. Positive burn produces a finite result with status finite (or exhausted when months equal zero), infinite set to false, and the three duration fields filled in. Currency units are not converted: use the same unit for cash and burn (USD, EUR, or any other single currency) and interpret the result in that unit’s months. Send a JSON object with two required finite numbers: cash_balance (aliases cash, balance, cash_on_hand, starting_cash) and monthly_net_burn (aliases burn, monthly_burn, net_burn, burn_rate, monthly_burn_rate). Cash must be greater than or equal to zero; a negative starting balance is rejected with invalid_input because runway from a negative pile is not a meaningful operating metric for this tool. Zero or negative burn means the entity is break-even or profitable on a cash basis: it is not consuming the balance at a steady rate, so the response omits runway_months, runway_days, and runway_years, sets status to infinite and infinite to true, and still echoes the inputs plus the formula string. Missing fields, non-numeric strings, NaN, and Infinity fail with invalid_input naming the field; those failures are not billed. Optional fields are never returned as null—when a duration does not apply, it is simply absent from the payload so clients that treat null and zero differently stay correct.
Where a cash runway API earns its keep
Investor updates, pitch decks, and grant reports often need a reproducible months figure that matches the spreadsheet version byte-for-byte; calling a tiny parse API from automation scripts avoids copy-paste drift across slides. Because the capability is tier-A parse, successful calls cost the published $0.002 with no model tokens; invalid input does not consume balance.
Integration use cases
Dashboard and FP&A automation
Call a deterministic API from finance dashboards so runway stays aligned with live cash and burn feeds without spreadsheet copy-paste.
Technical questions
How is cash runway calculated?
runway_months = cash_balance / monthly_net_burn when monthly net burn is positive. The API also returns approximate runway_days and runway_years from that months figure.
Can cash_balance be zero?
Yes. With positive burn, runway_months is 0 and status is exhausted. Negative cash is rejected as invalid_input.
What currency should I use?
Any single currency, as long as cash_balance and monthly_net_burn use the same unit. The calculator does not convert currencies.
What does the cash runway calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.