Race Fuel and Minimum Weight Calculator
Plan the fuel to load, reserve at the flag, projected race weights, and margin over your class minimum.
Calculator guide
Planning fuel load and minimum-weight margin
This calculator estimates the fuel to load for a timed or lap-count race, the reserve expected at the flag, and projected start and finish weights.
Inputs and calculation
- Race format and length, expected lap time when the race is timed, per-lap fuel consumption, formation laps, extra-lap allowance, and reserve percentage.
- Fuel type or measured density, car-and-driver weight without fuel, class minimum weight, and fitted ballast.
Timed-race laps are rounded up from race duration divided by expected lap time. Formation and extra-lap allowances are then added.
Fuel to load = total planned laps × consumption per lap × (1 + reserve percentage). Fuel mass uses the selected density.
Projected finish weight assumes planned fuel is consumed and only the reserve remains at the flag.
How to interpret the result
- Use the load result as a planning value, then compare actual fuel used after practice. A positive finish margin is the estimated amount above minimum weight.
- Additional ballast needed is zero when the projected finish weight meets the entered minimum; otherwise it shows the calculated shortfall.
Assumptions and limits
- Consumption is treated as constant for race, formation, and allowance laps. Driving pace, cautions, weather, fuel temperature, and measurement error can change actual use.
- Series rules differ on when and how vehicles are weighed. Confirm whether driver, fluids, and ballast are included before relying on the weight result.
Example: 30-minute sprint race
A 30-minute race at 90 seconds per lap produces 20 race laps. One formation lap, one extra lap, 0.45 gal per lap, and a 10% reserve produces a 10.89-gallon starting load.
Connect the plan to real race data
TuneWorks keeps setups, sessions, vehicle weight, weather, notes, and ECU logs together for the next event.