Race Weight Penalty Calculator

Extra weight slows a race car down because it reduces acceleration out of every corner and increases braking distance into every corner, and this calculator models that effect with a widely-cited paddock rule of thumb: roughly 0.03 seconds per lap for every kilogram added, on a 100-second lap. It scales that base rate by your actual lap time (a longer lap has more time for the weight penalty to compound) and by a track-type factor — short, technical circuits with heavy braking and acceleration are rated 1.2x more weight-sensitive, medium circuits are the 1.0x baseline, and long, high-speed circuits are 0.8x less sensitive, since sustained high speed is influenced more by aerodynamics and power than by mass. Multiplying additional weight by the per-kg-per-second rate, by base lap time, and by the track factor gives the time penalty per lap directly; that same result is shown too as a share of lap time and summed across a 10-lap stint.

The equivalent horsepower figure takes a different, simpler shortcut: it assumes power-to-weight scales linearly, so a given percentage increase in weight requires roughly the same percentage increase in power (against an assumed 300 HP baseline) to hold lap time constant — this is a rough power-to-weight approximation, not a physics-based drivetrain simulation. All of this is meant for ballpark stint planning (fuel load, driver weight, added ballast) rather than a precise setup tool: real weight sensitivity varies by car, tire, aero package, and specific corner layout far more than a single track-type multiplier can capture.