iPhone Screenshots
Description
PerfDial times your acceleration runs with the GPS and motion sensors in your iPhone, and keeps every run on your phone.
Mount the iPhone, tap Go and drive. PerfDial finds the start and the stop itself, and times the intervals the run crossed: 0-60, 0-100, 60-100, 80-120 or 100-200 km/h.
WHAT IT DOES
- Auto run. One screen and nothing to set up: tap Go, start from a standstill, and the list fills in with every standard interval the run crosses.
- Choose your own test instead: a standing start, a rolling start or a custom speed range.
- A run is checked before it is timed. If the mount, the sky or the standstill was not right, the run shows no time and says why, rather than a doubtful number.
- Data quality on every result: a grade, plus a plain sentence about what the sensors saw.
- History: every saved run, grouped by day, with favourites and delete.
- Compare two runs side by side, with both traces on one chart.
- Virtual dyno. From one dedicated pull, PerfDial estimates engine power and torque, shows a margin, can average the pull with its return pull, and corrects for the weather when the phone's barometer has a reading.
- Charts of speed, acceleration and distance against time.
- Export. Share the whole recording as JSON, or the processed table as CSV, whenever you want to.
- Onboarding and How It Works: four short cards on the first launch, and a page that explains what the app measures and why a run can have no time.
- Your units: speed in km/h or mph, power in horsepower, torque in newton-metres.
iPHONE DUO
On iPhone Duo the layout adapts to the folded and unfolded screens, and the live run and the result keep clear of the fold. Folding or unfolding the phone during a run ends that run with no time, because the sensors moved.
WHAT YOU NEED
- An iPhone running iOS 26 or later, with GPS. Real runs need open sky and a firm mount.
- A closed road or track where testing is allowed, and a standstill to start from.
- PerfDial asks for Location While In Use, and for Precise Location for the seconds of a run, because approximate location cannot measure speed. The accelerometer and the gyroscope need no extra permission; the barometer does, so iOS asks for Motion & Fitness the first time a dyno pull starts.
SAFETY
Before the first run, PerfDial shows this notice and the driver has to acknowledge it:
"Use PerfDial only on a closed road or track where this is allowed. Never use it on public roads, in traffic or above the speed limit. Mount the iPhone and do not touch it while driving. The figures are estimates, and the driver is responsible for driving safely."
The app never asks for a tap while driving: the start and the stop are detected for you, and the phone is meant to stay mounted. The Dyno procedure gives the same rule: every pull is meant for a closed road or track where this is allowed.
YOUR DATA
No account, no login, no server, no cloud sync, no analytics, no advertising and no third-party SDKs. Location, motion and air-pressure readings are processed on your iPhone and stored in the app's own database on the device, which can be included in your own iPhone backup. Nothing is uploaded unless you choose to export a run yourself, and even then the file goes only where you send it. PerfDial's App Store privacy label says that no data is collected.
ABOUT THE NUMBERS
Every physics output is labelled as estimated: estimated power, estimated torque, estimated revs (RPM). The app makes no accuracy claim, states no tolerance or percentage, and never compares a run with a published time. A run's time is what your own car and your own phone measured, and the quality grade tells you how the conditions were.
iPhone is a trademark of Apple Inc., registered in the U.S. and other countries and regions. IOS is a trademark or registered trademark of Cisco in the U.S. and other countries and is used under license. PerfDial is an independent product, not affiliated with, endorsed by or sponsored by Apple.