Drag racing math, built for the phone in your pocket
Horsepower, gearing, compression, air. The calculators drag racers have always needed — rebuilt for the phone in your pocket, unified around your combo, with every formula shown in the open. Free, no account, no sign-up.
Try two now — no sign-up, no catch
Both pre-fill from your saved combo once you set it. All 28 calculators →
Start here
Old calculator sites make you retype your weight, tire and gear into every single form — and one typo makes two tools disagree about your own car. RaceCombo keeps one saved combo in your browser and pre-fills every calculator from it. Same car, same numbers, every time.
The library
Track air
Density altitude moves your ET and your tune. Every track page fetches current conditions for that strip and solves the air — or takes your weather station readings directly.
The paid layer
Calculators answer questions. They don't remember anything. The Tuning System is the memory — a logbook, an air tracker and a change planner that live in your browser, built on your combo. One payment, yours to keep.
Included in the $39 Tuning System
Every pass saved and searchable — ET, MPH, 60 ft, air and notes — in your browser, printable for the trailer wall. Spot the pattern in your own car instead of guessing.
Included in the $39 Tuning System
Log the air and your jet changes through the day and see the trend line. When the sun drops and the air gets good, you already know the move.
Included in the $39 Tuning System
Two setups side by side — trap RPM, speed and shift landings for each — before you spend a dollar on parts.
Included in the $39 Tuning System
Guided worksheets that turn the free calculators into a decision: is the converter right, and where should this engine really be shifted?
Racer packs
one-time
one-time
one-time
Learn the why
Every calculator on this site shows its formula on the page. No black boxes, no "proprietary algorithm" — racing math belongs to racers, and you should be able to check our work with a pencil. The free library will stay free; paid products are one-time purchases that live in your browser, not subscriptions that hold your data hostage.
Weather data by Open-Meteo. Track elevations verified against published track and sanctioning-body sources at build time. Racing is dangerous — these tools inform decisions, they don't make your car safe; follow your track's and sanctioning body's rules.