Coriolis Effect

Due to the rotation of the Earth the Coriolis effect causes bullets to deflect to the right in the northern hemisphere and to the left in the southern hemisphere. Also, bullets are deflected vertically and drop less than expected when shooting East and more than expected when shooting West.

The amount of horizontal and vertical deflection depends on the latitude of your shooting location and the direction (azimuth) you are shooting. A detailed explanation can be found in the Wikipdia Coriolis effect article on-line. In this program the Coriolis effect is combined with wind drift, bullet drop and path in graphs and charts.

While not generally a factor at ranges under 400 yards, the Coriolis effect can be important to long range shooters wanting to take into account this known factor.


To include the Coriolis effect in the wind drift, drop and path calculations, click the Off button just to the right of the Coriolis parameter to set it to On. This not only turns on the Coriolis effect calculations, but reveals two more parameters that are needed to calculate the Coriolis effect.

You can turn the Coriolis effect calculations off at any time without altering those parameters by clicking the On button to set it to Off.

The Shooting Dir parameter is the compass direction from the shooter to the target where true north is 0 degrees, east is 90 degrees, south is 180 degrees, and west is 270 degrees.
The Latitude parameter is the shooting location's latitude in degrees. Latitude for North America is shown in the map to the right. For locations south of the Equator enter a negative number such as -30 for Australia.