Burn Rate & Runway Calculator — Months of Cash Left
Month-by-month cash projection
Enter your cash balance, monthly revenue, and monthly spend to see gross burn, net burn, and how many months of runway are left. Add month-over-month growth for revenue and for costs and the projection bends the way a real plan does — it tells you whether you reach break-even before the money runs out. Everything is calculated in your browser; your numbers are never uploaded.
What belongs in monthly spend
Burn is a cash number, not an accounting one. The test for every line is the same: does money leave the bank account this month? Optimistic runway estimates usually trace back to one of the rows below being left out.
| Line item | In or out | Why |
|---|---|---|
| Payroll and contractors | Include | Gross salaries plus employer taxes and benefits — the amount that actually leaves the account. |
| Rent, hosting, software | Include | Every recurring bill, including annual plans paid upfront, spread across the months they cover. |
| Marketing and sales spend | Include | Ad budgets, agencies, events. Usually the line you can cut fastest when runway gets short. |
| Loan and interest payments | Include | Principal repayments are cash out, even though an income statement puts them below the line. |
| Taxes collected but not remitted | Include | VAT and payroll tax sitting in your account is not your money. Model the month it leaves. |
| Depreciation and amortisation | Exclude | No cash moves. It belongs in the P&L, not in a burn number. |
| Invoices received but unpaid | Exclude | Count them in the month you actually pay, not the month the invoice arrived. |
| The round you hope to close | Exclude | Runway is what you have, not what you expect. Model the raise separately as a scenario. |
How much runway is enough
Runway is only half an answer — the other half is what you plan to do with it. These bands are the rough consensus among seed and Series A investors.
| Runway | Read | What it means in practice |
|---|---|---|
| Under 6 months | Critical | Too late to raise from strength. Cut costs now and treat every week as a decision point. |
| 6–12 months | Raise now | A round takes three to six months from first meeting to money in the bank. This is the window. |
| 12–18 months | Comfortable | Enough time to hit a milestone that changes the story before you need the next cheque. |
| 18–24 months | Target after a round | What most seed and Series A investors expect you to plan for once the money is wired. |
When one number stops being enough
This calculator moves your costs along a single growth curve. Real plans do not: two hires land in March, a price change hits in Q3, churn drifts up a point. If you are keeping that in a spreadsheet, Adlega does the same job as a connected 36-month model — MRR, hiring, costs, cash flow and runway all recalculate from one changed assumption, and the output comes out in the shape investors ask for. Built for SaaS founders who have outgrown a tab per scenario.
How it works
- 1 Enter cash and monthly spend Type the cash sitting in your accounts today and everything that leaves them in a normal month — payroll, contractors, rent, hosting, tools, ad budget, taxes.
- 2 Add revenue and growth rates Enter the cash you collect each month, then optional month-over-month growth for revenue and for spend. Leave growth at 0 for a flat, straight-line projection.
- 3 Read the runway and the month-by-month table You get gross burn, net burn, months of runway, and the date the balance hits zero. The table shows each month's revenue, spend, net burn, and closing cash, plus whether you are default alive or default dead.
Your data stays private
All processing happens entirely in your browser. No files, text, or data are ever sent to our servers. You can disconnect from the internet and this tool will still work.
Frequently asked questions
- How do you calculate burn rate?
- Gross burn is all the cash leaving the business in a month. Net burn is gross burn minus the cash you collect that month: net burn = monthly spend − monthly revenue. Spend 70,000 and collect 20,000 and your gross burn is 70,000 while net burn is 50,000. Runway is then cash ÷ net burn — about 10 months on a balance of 500,000.
- What is the difference between gross burn and net burn?
- Gross burn measures your cost base; net burn measures how fast the bank balance actually drops. They are equal only at zero revenue. Investors usually ask for net burn, but gross burn is what tells you how much you would have to cut to survive a bad quarter, so this calculator shows both.
- How is cash runway calculated when revenue is growing?
- With flat numbers, runway is simply cash ÷ net burn. Once revenue or costs grow, that formula stops holding, so this tool carries the balance forward month by month: it compounds revenue and spend by their own growth rates, subtracts one from the other, and deducts the result from cash. Runway is where the balance crosses zero, interpolated inside the final month rather than rounded to a whole one.
- What does default alive mean?
- The term is Paul Graham's: a company is default alive if its current growth and spending get it to profitability before the money runs out, and default dead if it does not. This calculator flags it — when revenue overtakes spend inside the projection and the balance never hits zero on the way there, you are default alive. When it does not, the fix is a raise, faster growth, or lower costs.
- What should I include in monthly spend?
- Everything that leaves the bank account: gross payroll with employer taxes, contractors, rent, hosting, software, marketing, loan repayments, and tax you have collected but not yet remitted. Leave out non-cash items such as depreciation. If a large annual bill falls in one month, either spread it or model that month separately — forgetting it is the most common reason a runway number comes out optimistic.
- How many months of runway should a startup have?
- Most investors expect 18 to 24 months after a round. Since a raise usually takes three to six months from first meeting to wired funds, 12 months of runway is the point to start preparing, and six months is where your options begin to close. Below that you are negotiating from weakness.
- Are my financial numbers private?
- Completely. The calculator is plain JavaScript running in your browser. Your cash balance, revenue, and costs are never sent to a server, logged, or stored — disconnect from the internet and the page keeps working.