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Suunto Core User Guide

How Alti & Baro works

To get the right readings from Alti & Baro, it is important to understand how Suunto Core calculates altitude and sea level air pressure.

Suunto Core constantly measures absolute air pressure. Based on this measurement and reference values, it calculates altitude or sea level air pressure.


Keep area around sensor free of dirt and sand. Never insert any objects into the sensor openings.

Getting correct readings

If you are engaged in an outdoor activity that requires you to know the air pressure, you need to enter the altitude reference value for your location. This is found on most topographic maps. Your Suunto Core will now give you the correct readings.

To get the correct altitude readings, you need to enter the sea level air pressure reference value. The sea level air pressure reference value relevant to your location can be found in the weather section of the local newspaper or on the websites of national weather services.

Absolute air pressure is measured constantly Absolute air pressure + altitude reference = Sea level air pressure

* Absolute air pressure + sea level air pressure reference = Altitude *

Changes in local weather conditions will affect altitude readings. If local weather changes often, it is advisable to reset the current altitude reference value frequently, preferably before starting your journey when the reference values are available. If local weather is stable, you do not need to set reference values.

Getting incorrect readings

Altimeter profile + standing still + weather change

If your altimeter profile is on for an extended period of time with the device in a fixed location while the local weather changes, the device will give incorrect altitude readings.

Altimeter profile + altitude moving + weather change

If your altimeter profile is on and the weather changes frequently while you climb in altitude or go down in altitude, the device will give you incorrect readings.

Barometer profile + altitude moving

If the Barometer profile is on for an extended period of time as you climb in altitude or go down in altitude, the device assumes that you are standing still and interprets your changes in altitude as changes in sea level air pressure. It will therefore give you incorrect sea level air pressure readings.

You’re on the second day of your two-day hike. You realize that you forgot to switch from the BarometerBarometer profile to the altimeterAltimeter profile when you started moving in the morning.You know that the current altitude readings given by your watch are wrong. So, you hike to the nearest location shown on your topographic map for which a altitude reference value is provided. You correct your altitude reference value accordingly. Your altitude readings are correct again.

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