What to enter
- Cash now
- Business cash you can spend today. Not personal savings, unused credit, or money you haven't received.
- Cash collected
- What customers pay into your account in a normal month. Use cash, not MRR. Leave out yearly payments, and add the next one as a planned change, so it's counted once. Leave out loans and investment.
- Cash paid out
- Everything that left the account in a typical month, including your own pay, payment fees, and taxes. The calculator adds no fees of its own.
If your months vary, use an average. Pilot suggests at least three months.
Adding a forecast
Growth rates are per month and compound: 10% a month is about 214% a year. A blank rate means 0%. A rate is a guess, so try a slower one too. Growth starts in month 2.
Planned changes are for costs and income that jump instead of growing. Month 1 is the first month from today, and amounts don't grow.
| Event | Type | Repeats | Example |
|---|---|---|---|
| A hire | Money out | Every month | $2,000 from month 4 |
| A yearly renewal | Money out | Every 12 months | $1,200 from month 3 |
| A tax bill | Money out | Once | $5,000 in month 6 |
| A signed contract | Money in | Once | $6,000 in month 2 |
Only add money in you're sure of. A planned change can't lower a cost, so enter a cut you've already made in cash paid out.
How to read the result
Today's runway assumes nothing changes. The forecast runway sits beside it. Runway rounds down, so 6.6 months means cash runs out during month 7.
| Forecast result | What it means |
|---|---|
| A number of months | Cash runs out in that month. The detail says if income catches up later, or if a planned payment caused it. |
| Covers costs from month N | Income covers costs from month N. No cash-out in the next 60 months. |
| Covers costs every month | Income covers costs from month 1. No cash-out in the next 60 months. |
| More than 60 months | No cash-out in the next 60 months, but income still doesn't cover costs. |
If cash runs out before income catches up, you also see the extra cash you'd need today to reach break-even.
A solo SaaS with a yearly renewal
Example
You have $20,000, collect $3,000 a month, and pay out $6,000, including $2,500 to yourself. Cash lasts 6.6 months and runs out in month 7.
With 6% monthly revenue growth and a $1,200 renewal every 12 months from month 3, cash lasts 8.4 months and runs out in month 9. Income covers costs from month 13. $2,590.17 more today would get you there, since the balance is lowest in month 12.
How is startup runway calculated?
Runway is the cash you have divided by the cash you lose each month.
Runway
Formula
Net burn = cash paid out − cash collected
Runway in months = cash now ÷ net burn
Gross burn is everything you pay out in a month. Net burn is gross burn minus what customers paid you, as Carta defines them. For example, $20,000 ÷ ($6,000 − $3,000) is 6.6 months, rounded down.
A positive net burn means your cash is shrinking. Zero means you're at break-even, so the balance holds. A negative net burn means customers pay you more than you spend, and the calculator shows it as net cash in.
The forecast works one month at a time: last month's balance, plus cash collected, minus cash paid out, plus or minus any planned change. In the month cash runs out, money counts as spread evenly, which gives the decimal.
Why does growth start in month 2?
Month 1 is the normal month you described, so the forecast starts from the numbers you actually have today. Growth changes things from month 2 on. Starting it in month 1 would assume a change that hasn't happened yet, which can make the runway look longer or shorter than it is.
Should you use MRR or cash collected?
Use cash collected. Runway depends on when money reaches your account, and MRR spreads it out.
Stripe's example is a customer who pays $1,200 upfront for a year. That counts as $100 of revenue a month, but all $1,200 arrives the day they pay. Enter $100 a month and you'd spread out cash that comes in one go. Enter $1,200 every month and you'd count it twelve times.
So keep yearly payments out of the monthly figure, including when you average recent months. A payment you've already received is part of your cash now. Add the next one as a planned change in the month you expect it, if you're confident of it. That way each payment is counted once. If you're still pricing a yearly plan, the annual plan discount calculator shows what a discount costs you and how much cash it brings in upfront.
Should you count your own pay?
Yes. Your pay is a business cost. Without it, the runway shows how long the business lasts, not how long you can keep working on it.
If you don't pay yourself yet but plan to, add it as a planned change: money out, every month, from the month you'll start.
What is a good runway for a bootstrapped startup?
There's no single number. Most runway targets online come from fundraising advice, where runway means time left to raise the next round. For a bootstrapped business, the better question is whether cash lasts until customers pay enough to cover your costs. The forecast answers that.
Paul Graham calls this being default alive: if your costs stay the same and revenue keeps growing at its recent rate, do you become profitable before the money runs out? To try it here, enter your recent monthly revenue growth, leave expense growth at 0%, and add no planned changes. The calculator compares monthly cash in with cash out. It doesn't measure accounting profit, and it doesn't label your result.
To see how long your growth rate takes to reach a revenue target, such as the MRR that covers your costs, use the MRR goal calculator.
Why does another calculator show a different runway?
Usually it does one of these:
- Asks for MRR instead of cash. Yearly plans make the two very different.
- Starts growth in month 1, which can add a month or more.
- Rounds to the nearest tenth. This one rounds down, so it never overstates.
- Shows "infinite" runway when cash stops falling. This one looks 60 months ahead and tells you when there's no cash-out in that time. A forecast further out is mostly guesswork.
What this calculator doesn't cover
It's a monthly model of business cash. It leaves out late payments, loans, interest, fundraising, and personal savings. Churn isn't a separate input, so build it into the revenue growth rate. If new sales add about 8% a month and cancellations take away 3%, enter about 5%.
To find the MRR that covers your costs, use the break-even MRR calculator. The burn multiple calculator shows how much cash you burn for each dollar of new ARR, and the SaaS metrics calculator gives a one-month picture of MRR and retention.