Tacho is a speedometer, a compass and a weather app.



The speed is shown in kilometers per hour, miles per hour, meters per second or knots.


The distance is shown in kilometers, miles, nautic miles or meters.


The compass shows your direction. It can be configured in SettingsTacho to use true north. The default is the magnetic north.

Compass Calibration

To improve the accuracy of the compass you should calibrate it before using. To calibrate the compass hold your device flat and face up in front of you and move it in a figure of an eight.

Temperature, wind direction and wind speed

Tacho shows local temperature, wind direction and wind speed. Wind speed is shown in Beaufort, kilometers per hour, miles per hour, meters per second or knots.

The temperature unit can be configured in the Settings app. Go to GeneralLanguage & RegionTemperature Unit. You can switch the temperature unit in the iPhone Weather app too.


The altitude is shown in meters or feet and can be configured in the Settings app.
The app offers two methods to measure the altitude: barometer and GPS.

Barometric altimetry

The altitude is calculated from local air pressure, local temperature and the air pressure at sea level. Your device measures the local air pressure with the integrated barometer1. Sea level air pressure and temperature are loaded at regular intervals from nearby weather stations.

Barometric altimetry is very sensitive to height changes. But it is sensitive to weather changes too, so it is only reliably in stable weather conditions.

Satellite altimetry (GPS)

The satellite based height measurement is less accurate compared to barometric altemitry, but it is independent from weather conditions.


Incline is shown in percent or degree. The calculation is based on changes in air pressure measured with the barometer1 and is therefore only reliable in stable weather conditions.

System requirements

Tacho requires an iPad with GPS or an iPhone and iOS 12.2 or above.

Trouble shooting

The compass shows inaccurate results.

The compass is a sensitive measuring device. It may be disturbed by external influences, such as magnets or shocks. If the compass shows inaccurate results, calibrate it.

The wind needle is not shown.

This might have several reasons:

  • no wind
  • turning wind
  • no data
Weather data is not loaded.

Make sure the switch Weather Conditions in SettingsTacho is enabled and check your network connection.

1Requires iPhone 6, iPhone 6s, iPhone 7, iPhone 8, iPhone X, iPhone XS, iPhone XR, iPhone 11, iPhone 11 Pro, iPad Air 2, iPad mini 3, iPad Pro or iPad (5. Generation).