Originally Posted by cyccommute

From Sunnto





A Google search of accuracy of the two measurements give a raw error of 10m to 20 m for GPS (35 to 70 feet) while barometers are accurate to ±15 meters. The error is almost the same per measurement. GPS may suffer more from a refresh rate that a barometer doesn’t experience. GPS is averaged over several seconds while barometric pressure may be closer to instantaneous as it is an on-board instrument. If you are stationary, this may no make much difference but when mobile, that averaging can lead to larger errors. Most phones have both GPS and a barometer to increase accuracy.