Real-time ET prediction at the strip. Powered by OBD-II live data, gear detection, and precision launch algorithms — built for serious drag racers.
Every feature engineered around one goal: predict your ET before you roll through the traps.
Calculates elapsed time in real-time using vehicle speed, power output, and track data — updating continuously during your run.
Connects via Bluetooth to your OBD-II adapter and pulls live PIDs — RPM, speed, throttle position, and more at high polling rates.
Four-tier gear detection: standard PIDs, manufacturer-specific protocols, ratiometric calculation, and manual fallback — covers nearly every drivetrain.
Tracks 60-foot times, reaction time, and launch RPM to identify where you're leaving time on the table.
Every pass logged with full telemetry. Compare runs side-by-side and track performance trends over your season.
Automatically adjusts predictions for temperature, humidity, and altitude — because track conditions change every session.
Connect a RaceBox Mini, Mini S, or Micro at 25Hz, or a Qstarz BL-1000GT / BL-818GT at 10Hz for precision timing that goes beyond what your phone's built-in GPS can deliver.
Plug in, stage up, and let HowFast do the math while you drive.
Pair your OBDLink MX+, vLinker FD+, or ELM327 adapter via Bluetooth. HowFast handshakes with the adapter and begins streaming live vehicle data instantly.
Enter your gear ratios, tire size, and power estimates — or let the app learn your car's behavior automatically over your first few runs.
Tap the Arm Run button to enter the launch screen and get ready to stage. When you leave the line, HowFast captures your launch data in real time.
As you accelerate through each gear, your predicted ET updates live on screen — so you know your number before the timeslip prints.
HowFast is tested and optimized for the most popular OBD-II adapters and external GPS devices at the track.
Full protocol support including manufacturer-specific PIDs. Fastest poll rates and most reliable connection at the strip.
Excellent Ford/GM support. Ford-specific protocols enable direct transmission gear reporting on compatible vehicles.
Works with standard OBD-II PIDs and ratiometric gear calculation. Ideal for older vehicles or budget setups.
25Hz Bluetooth GPS purpose-built for motorsport. HowFast connects via RaceBox's open BLE protocol for high-resolution speed and timing data.
10Hz Bluetooth GPS with proven track record at the drag strip. Full support for both models via the Qstarz BLE protocol.
No external hardware required. HowFast runs on your iPhone's built-in GPS for a zero-cost setup right out of the gate.
Free download for iOS and Android. Plug in an OBD-II adapter and you're ready for your first pass.
We recommend the OBDLink MX+ or vLinker FD+ for best results — they support manufacturer-specific protocols for direct gear detection. Generic ELM327 adapters work but may use ratiometric gear estimation instead of direct reporting.
Yes. HowFast supports both. Automatics benefit most from live gear detection, while manuals use RPM and speed data to calculate current gear ratiometrically. Manual fallback input is also available.
Accuracy improves with each run as the app calibrates to your specific vehicle. After a few passes, predictions are typically within 0.05–0.1 seconds of actual ET — more than close enough for bracket racing and performance tuning decisions.
The core app is free. A small number of advanced features — like extended run history and telemetry export — may be available via a one-time in-app purchase in a future update.
HowFast requires iOS 16 or later and is optimized for iPhone 12 and newer. Bluetooth 4.0+ is required for OBD-II adapter connectivity.
Yes — HowFast is designed for use at any sanctioned drag strip. It works with the standard quarter-mile and eighth-mile formats and can be configured for either distance in settings.
Having trouble with the app or your OBD-II connection? Send us a message and we'll get back to you fast.
We'll follow up at your email within one business day.