There are two classic ways to lose a race in the fuel menu before you've turned a wheel. Under-fuel and you're coasting to the line on fumes, praying. Over-fuel and you carried dead weight through every corner of the opening stint, slower than everyone who didn't. Both come from guessing. Neither is necessary — the maths is genuinely simple once you have the right three numbers.
The three numbers
Burn per lap — how many litres you actually use on a green-flag lap. Race length — laps, or a time you convert to laps using your average pace. Tank size— your car's maximum. Everything else is arithmetic.
Working an example
Say you burn 2.7 L/lap and the race is 20 laps. 2.7 × 21 = 56.7 L. If your tank holds 120 L, you finish no-stop with margin to spare — so the real question becomes tyres and pace, not fuel. If the race were 60 laps, 2.7 × 61 = 164.7 L against a 120 L tank means at least one stop, and now you plan stint lengths around the tank: roughly 44 racing laps per full tank, so two stints with a comfortable buffer.
The part people forget: fuel changes your pace
A full tank can be 40–70 kg of fuel depending on the car. That weight makes your opening laps measurably slower and works the tyres harder early. Which means your averagelap time isn't constant — it drifts as the tank empties. Plan a 60-lap race on your qualifying pace and you'll under-fuel; plan it on your heavy out-lap and you'll over-fuel. The honest number is your observed race-stint average, fuel load and all.
Let the car tell you, not a calculator
The reason spreadsheets are a pain is that every input is a guess unless you've measured it. MyRacingData reads your real fuel burn and your real per-lap pace straight from your telemetry, so its strategy planner works from what your car actually did, not a hopeful estimate: litres to add for any race length, how many stops, and realistic stint lengths — including the pace drift as the fuel burns off.
Start free, drive a stint, and let it plan your next race from your own numbers — or see what a captured session looks like first.