Runway Math That Actually Survives a Board Meeting

Estimated reading time: 7 min

Three weeks before a funding round, a founder I know told her board they had 16 months of runway. Two weeks later, after her FD sat down with the model, the number was 9. Nothing had changed except who'd opened the spreadsheet.

This is the runway gap. It's the distance between cash divided by burn (the back-of-an-envelope number most founders have memorised) and runway as it actually behaves once you account for hiring plans, AR slippage, VAT cycles, and the fact that next quarter's costs aren't the same as last quarter's.

If you walk into a board meeting with the wrong number, one of three things happens. The good directors poke holes and you lose credibility. The bad ones don't, and you run out of cash earlier than you said you would. The worst ones are polite enough to wait six months before bringing it up.

The bad runway number

Cash divided by monthly burn. €1.8M in the bank, €120K monthly burn, "fifteen months of runway."

That's a sixth-form answer. It assumes burn is a flat line, that revenue is a flat line, that everyone pays you on time, that the tax authority sends no letters, and that the team you're about to hire has already started costing you money. None of that is true.

For an early-stage SaaS business in growth mode, the gap between this number and the real one is usually three to six months. Sometimes more. Always in the wrong direction.

Five adjustments that matter

1. Burn ramp.

If your hiring plan adds two engineers in May, a salesperson in July, and a customer success hire in September, your monthly burn at month twelve is not your monthly burn today. Take the cumulative impact of every signed offer letter and every committed budget line (software licences, agency retainers, office costs that scale with headcount) and project burn forward month by month, not as a flat average.

A SaaS company at €120K burn today with five hires across the next nine months will be running closer to €175K by month nine. Averaging that across the year hides where the cash actually leaves.

2. Seasonality.

Both sides of the P&L. Revenue: B2B SaaS in Europe loses August to summer holidays and December to Christmas. New ARR slows. Renewals push into Q1. On the cost side, most companies pay annual bonuses in March, run salary reviews in April, and spike hiring in September.

If your model treats December and February the same, you'll be wrong in ways the board will spot the moment the actuals come in.

3. AR collection timing.

This is the one founders miss most. Booked revenue is not cash. A €60K annual contract signed in March with 60-day payment terms is a piece of paper until late May, and the customer's AP team might quietly stretch that to 75. If your model assumes invoices land as cash in the month they're issued, you've put 30 to 60 days of working capital on the wrong side of the column.

Pull the last 12 months of your DSO. Use the actual number, not the contractual one. If your DSO is 52 days and your model assumed 30, you're underwater on a six-figure timing gap for a typical €1M ARR company.

4. Tax timing.

VAT returns. Corporation tax instalments. PAYE/PRSI cycles. None of them are smooth.

In Ireland, a growing company can carry a VAT credit position for months and then flip into a payable position the quarter their revenue mix changes. UK corporation tax lands nine months and a day after year-end, which catches founders by surprise the first time. PAYE/PRSI is monthly but disproportionately painful in months with bonus payments.

A SaaS business at €2M ARR with a 23% effective tax-cash rate is sitting on a six-figure year-end hit. If your runway model doesn't have it pencilled in, your real cash floor is below where you think it is.

5. Planned hires not yet in burn.

The hire you've offered but who hasn't started costs you nothing yet. The hire you've budgeted but not offered also costs you nothing yet. Neither shows up in the historical burn your runway calculation is built on.

Add them. Every signed offer letter not yet started. Every approved hire on the plan. Their salary, employer's PRSI or NI, software seats, equipment, and the recruiter fee if applicable. Backload them by start date, not by the month they were approved.

Three scenarios on one page

The number you bring to the board is not "our runway is 14 months." It's three scenarios, on one page, with the assumptions spelled out underneath.

Base case. Your honest plan. Hiring on the agreed schedule. Sales pipeline converting at trailing 12-month rates. Costs growing as planned. Tax and AR realistic.

Downside case. Pipeline converts at 60% of plan. AR slips by 15 days. One key hire delayed three months, with no offsetting cost cuts. This is the case your board most needs to see.

Upside case. Plan plus a credible bull-case input. A known deal closes. A marketing channel scales. A price increase holds. Don't fabricate this case. If you can't name the specific lever, leave it out.

The three numbers should tell a story. Base 12 months. Downside 8. Upside 16. That tells a board you understand your business. Base 14, downside 13, upside 15 tells them you didn't model anything. You just nudged the inputs by 5% and called it a sensitivity.

The board-proof runway slide

One slide. Three scenarios. Each one with the cash floor month and the single assumption that breaks it.

What kills credibility: twelve different numbers across the deck. Cash on hand on slide 6 that doesn't tie to the runway slide. A burn rate quoted as "blended" with no explanation of what's in or out. A runway that doesn't account for the fundraise you're sitting there to ask for.

What earns credibility: one number per scenario, the date the cash floor lands, and the single variable that moves it. "Base case runway: March 2027. The thing that moves it most is enterprise close rate. At 50% of plan, we're down to December 2026."

Boards don't want surprises. The fastest way to give them one is to bring a runway number that's been calculated wrong.

When to re-run

Monthly. At minimum.

Re-run after any decision worth more than 5% of monthly burn. A hire approved. A contract signed. A deal lost. A price change committed. Re-run before every board meeting and every investor conversation. Re-run when actuals come in and your DSO has moved more than three days.

A runway model that gets updated quarterly is a runway model that's wrong for two-thirds of the year.

We built Stratavor because most SME finance teams are running this calculation in a spreadsheet that gets touched once a month, by one person, in a hurry, the day before the deck is due. The canonical KPIs in the platform (cash runway, true burn, AR-adjusted cash position) bake in the five adjustments above by default. You see real runway, in three scenarios, refreshed against your actuals every time the data updates. No one is hand-keying it the night before the board meeting.

If you've sat across a board table watching someone you respect ask a question you couldn't answer, you know why this matters. Twenty minutes on a demo and you can see it on your own numbers.