HowFast – Drag Race Predictor

Real-time ET prediction, OBD-II gear detection, and run logging built for bracket racers. Free download — upgrade to Pro anytime.

Know your number before you stage.

HowFast predicts your elapsed time using your vehicle's real specs — engine, drivetrain, tires, and the air conditions at your track. Whether you're dialing in for bracket racing or just curious how quick your car really is, HowFast gives you a data-driven starting point that gets smarter every time you run.

Predict with confidence

HowFast builds your ET prediction from the ground up — horsepower, drivetrain loss, tire grip, shift times, and real-time density altitude correction. The more you run, the more accurate it gets. HowFast learns from your actual timeslips and adjusts future predictions automatically.

Built for the track, not the spec sheet!

No expensive GPS hardware required. Use your iPhone's built-in GPS for run detection and timing, or connect to a RaceBox or Qstarz external GPS unit for precision timing at up to 25Hz. HowFast automatically detects your run and starts logging — no tapping required.

Your logbook, is always with you! Every run is saved with your predicted ET, actual ET, speed, and conditions. Review your history, spot trends, and see how your tune is progressing over the season.

Export Every Run in the DynoLog app effortlessly! HowFast captures your ET, trap speed, 60-foot time, and atmospheric data at the strip. DynoLog is where that data becomes a permanent part of your build record — plotted on a performance timeline, correlated to every mod you've made, and exportable as a professional PDF build sheet.

After your pass, tap Export to DynoLog or login and the run lands in your build log automatically — no manual entry, no duplicate imports, no data left behind.

Upgrade to Pro — one time purchase, yours forever. Unlock the full HowFast experience with a single one-time purchase: OBD-II connectivity— see your RPM, TPS, gear you're in, in real time Multi-run comparison — overlay runs and telemetry to find where you're gaining or losing Unlimited vehicles in your garage CSV export — take your data anywhere

HowFast Pro is a one-time purchase. No subscription, no recurring charges. Whether you're a seasoned bracket racer chasing a perfect dial or a weekend warrior seeing what your car can do, HowFast is the smartest co-driver you've never had.