Corner Weight Calculator
Four scale pads in, the whole balance out - total, front and rear, left and right, and the cross weight percentage that decides how the car takes a corner.
Enter Your Scale Readings
Weigh the car as it races: driver aboard or ballasted in place, fuel load decided. This tool never adds a driver for you.
Weight Balance
The car from above
Every pair, itemized
| Pair | lb | % of total |
|---|
What cross weight is
Cross weight is the right front plus left rear corner weights as a percentage of the whole car: (RF + LR) / total. Over 50% the car "has wedge", under 50% it has reverse wedge. It matters because the two diagonals fight each other through a corner - the loaded diagonal takes more of the work, and which diagonal that is changes how the car rotates. Everything on this page is plain arithmetic with no empirical constants, which makes it a rarity in this section: the math carries no accuracy warning at all. The scale session carries all of it.
Who wants what number
Road racers and autocrossers, who turn both directions, generally chase 50% - a square car that behaves the same way in left and right corners. Circle track racers run deliberate wedge because they only turn left: more cross typically tightens the car mid-corner and less loosens it, which is why "putting a round of wedge in" is oval slang for killing oversteer. How much is a setup question this tool stays out of - it tells you where the car is, not where it should be.
The numbers are only as good as the pad
Corner weights move with everything: a scale pad an inch out of level, ten minutes of fuel burn, the driver's seat empty instead of occupied, tire pressures still cold from the trailer. Before trusting the percentages, level and zero the scales, set pressures, put the driver or equivalent ballast aboard, decide the fuel load, and roll the car or bounce the suspension to settle it after every change. A tenth of a percent of cross is about three pounds on a typical car - well inside what a sloppy session invents out of nothing.
What this tool will not do
It reports balance; it does not prescribe spring perch turns. Corner balancing is iterative - change one corner, re-settle, re-read - and the right move depends on the car's spring rates, its ride height targets and what you are optimizing for. The honest scope of a calculator is the arithmetic. If the session sends you shopping for stance instead, the tire size calculator and the wheel offset calculator live next door.