How to Switch Speed Units (km/h, mph, knots, m/s) on iPhone

TL;DR

SpeedTrace switches speed units instantly between km/h, mph, knots, and m/s, so the readout matches whatever you're doing — driving, sailing, running, or flying — without any recalculating in your head.

Steps

In SpeedTrace, open the units control.
Pick km/h, mph, knots, or m/s.
The readout updates instantly.
Switch anytime as your activity changes.

Why it works this way

Speed means different units to different people — mph on the road in the US, km/h elsewhere, knots on the water or in the air, m/s in the lab. Forcing one unit means constant mental conversion. SpeedTrace switches between all four instantly, so the number you read is already in the unit you think in, whatever you’re doing.

Tips & edge cases

Knots for sailing and flying; m/s for sports science.
Switch freely — it doesn’t interrupt your session.
Set it once for your usual activity and forget it.

FAQ

Which units are available? km/h, mph, knots, and m/s — switchable instantly.

Why knots and m/s? Knots suit sailing and flying; m/s suits science and some sports. SpeedTrace covers all four so the readout fits your activity.

Does switching lose my session? No. Changing units just changes the display; your session continues.