Use curb weight for the 0–60 model
Curb weight describes the vehicle in its ready-to-operate configuration before adding occupants and cargo. The U.S. vehicle-safety definition includes standard equipment and operating fluids. Check the manufacturer’s weight and notes for your exact trim and options before entering it in the calculator. 49 CFR § 571.3 definitions
Keep curb weight as the starting point for the 0–60, target-time, and power-to-weight tools. If you compare a modification that adds or removes hardware, enter that change from the same original weight.
Use total race weight for a quarter-mile estimate
Race weight is what the vehicle weighs during the pass, including the driver, the fuel actually aboard, and any equipment carried in the car. If the facility offers a scale, follow its instructions and weigh the car in the same configuration you plan to run.
To estimate race weight from a spec sheet, add the driver and the gear that were excluded from the listed weight. Adjust for the difference between the fuel in the specification and the fuel on board. Add only that difference because curb weight already includes a fuel allowance.
Worked example at 400 hp
| Item | Weight |
|---|---|
| Listed curb weight | 3,500 lb |
| Driver | +175 lb |
| Additional gear | +25 lb |
| Fuel adjustment, same load as the specification | 0 lb |
| Total race weight | 3,700 lb |
At 400 hp, the calculator estimates 12.23 s at 111.5 mph with the as-run weight. Using only the listed curb weight would estimate 12.00 s at 113.6 mph. That difference comes entirely from the input weight.
For comparisons between track days, keep the actual fuel and driver weight with your notes alongside elapsed time and trap speed. Quarter-mile formula and assumptions