Size a funding round from the cash needed to reach your next milestone, plus time to raise again. Model planned hires and a revenue delay before choosing the amount. The seed example below compares €612,000, €700,000 and €1.1 million rounds, showing what each can cover.
Is today's burn times 18 enough runway to raise?
Multiplying today's burn by 18 sizes a round for the company you have, not the one the money will build. For the example six-person SaaS company, 18 months at its €34,000 net burn is €612,000. That number feels safe because it matches the guideline, but the money will be spent on hires, and every hire raises the burn.
The company is raising a seed round. It has €6,000 of monthly recurring revenue and spends €40,000 a month, so its net burn today is €34,000. The founders' milestone for the next raise is €46,000 of MRR, about €550,000 a year, and they believe they can reach it in 18 months.
Model the company the money will build
To size a round, model the company the money will build, not today's team. The plan adds four people over two years, most of them in the first year, plus more spending on tools and marketing as revenue grows, so gross burn rises from €40,000 to €68,000 a month. Revenue follows the founders' plan. Figures are monthly averages for each quarter.
| Quarter | Gross burn / month | Revenue / month | Net burn / month | Cash used so far |
|---|---|---|---|---|
| 1 | €40,000 | €6,000 | €34,000 | €102,000 |
| 2 | €50,000 | €10,000 | €40,000 | €222,000 |
| 3 | €56,000 | €16,000 | €40,000 | €342,000 |
| 4 | €60,000 | €24,000 | €36,000 | €450,000 |
| 5 | €62,000 | €34,000 | €28,000 | €534,000 |
| 6 | €64,000 | €46,000 | €18,000 | €588,000 |
If everything goes to plan, the company hits €46,000 of MRR at the end of month 18 having spent €588,000. On the €612,000 round it would have €24,000 left: less than two months of burn, with a fundraise still to run.
Tools that recompute runway when the plan changes save you rebuilding this table each time an assumption moves.
What if revenue runs six months late?
If revenue arrives six months behind plan while costs stay on schedule, the example company needs €954,000 and reaches the milestone in month 24 instead of month 18. Costs are the easy part to predict because you control them. Revenue is not. Run the same costs with revenue arriving six months behind plan:
| Quarter | Gross burn / month | Revenue / month | Net burn / month | Cash used so far |
|---|---|---|---|---|
| 1 | €40,000 | €6,000 | €34,000 | €102,000 |
| 2 | €50,000 | €6,000 | €44,000 | €234,000 |
| 3 | €56,000 | €6,000 | €50,000 | €384,000 |
| 4 | €60,000 | €10,000 | €50,000 | €534,000 |
| 5 | €62,000 | €16,000 | €46,000 | €672,000 |
| 6 | €64,000 | €24,000 | €40,000 | €792,000 |
| 7 | €66,000 | €34,000 | €32,000 | €888,000 |
| 8 | €68,000 | €46,000 | €22,000 | €954,000 |
The milestone now arrives at the end of month 24, and getting there costs €954,000. A six-month slip on the revenue side adds €366,000 to the bill, because the costs arrive on time.
How much extra runway do you need to raise again?
Add about six months of net burn at the milestone to every case, because you cannot start the next raise with an empty account. NYU's entrepreneurship team, in The Runway Equation, estimates about six months to raise a round, which is why they recommend 18 to 24 months of runway. So add six months of net burn at the milestone to each case:
round = cash used to reach the milestone + 6 x net burn at the milestone plan case: 588,000 + 6 x 18,000 = 696,000 late case: 954,000 + 6 x 22,000 = 1,086,000
Three round sizes side by side
Three round sizes give three outcomes. A €612,000 round (today's burn x 18) works only if nothing slips, a €700,000 round (plan plus time to raise) covers the plan but not the late case, and a €1,100,000 round (late case plus time to raise) covers both.
| Round | If the plan holds | If revenue runs six months late |
|---|---|---|
| €612,000 (today's burn x 18) | Milestone in month 18 with €24,000 left | Out of cash in month 14, before the milestone |
| €700,000 (plan plus time to raise) | Milestone in month 18 with €112,000 left | Out of cash in month 16 |
| €1,100,000 (late case plus time to raise) | Milestone in month 18 with €512,000 left | Milestone in month 24 with €146,000 left |
The €612,000 round only works if nothing slips. The €700,000 round covers the plan and fails in the late case. The €1.1M round covers the modeled cash use in both cases, including the six-month fundraising allowance.
Choosing between them is a judgment about how much you trust your revenue plan and how much dilution you accept. The table shows the price of that judgment: about €400,000 of extra funding separates "works if we are on time" from "works if we are six months late".
What if investors offer less than you need?
When investors offer less than the round you modeled, shrink the plan and leave the six months for raising alone. If the market will give you €800,000 and your late case needs €1.1M, hiring timing is the main lever. One €8,000-a-month hire moved six months later saves €48,000, leaving €252,000 of that gap. Combine realistic hiring delays with other savings or a nearer milestone, then rebuild the cash calendar.
Raising less and hoping to be on time is how companies end up in what Paul Graham calls the fatal pinch: lots of burn, slow growth and a fundraise that has to work. The same essay says Y Combinator tells founders to act as if each round is the last money they will get.
After the money arrives
After the money arrives, the model that sized the round is also your spending plan. Before each planned hire, check actual revenue against the plan and against the late case, and delay the hire if you are tracking the late one. Check your run-out date every month, and ask each quarter whether the company is default alive. The cash runway calculator handles the quick check from three numbers.
A monthly review that keeps the plan honest is where that check happens.
In Plainhub, each planned hire can sit on the Plans page as a draft with its start date, next to today's runway, until you commit it. Committed plans only count from their start date, so the runway you see today reflects the team you have now.