Wind Deflection Shot MPH Calculator

Wind drift in long-range shooting

Three things drive wind drift: how fast the crosswind is blowing, how long the bullet spends in the air, and its ballistic coefficient (BC). A full-value wind hits at 90° to the line of fire and gives you the worst deflection, while a tail or headwind barely registers. Take a .308 Winchester 175 gr bullet at 1000 yards in a 10 mph full-value crosswind: it drifts somewhere around 70 inches (about 6.7 MOA), and that number shifts with muzzle velocity and BC. The higher the BC, the shorter the flight time and the less the bullet gets shoved sideways. Once you're shooting at extreme range, you also have to account for Coriolis and the Eötvös effect, where eastward shots pick up a vertical offset from the Earth's rotation.

Applications

You'll see this come up in PRS (Precision Rifle Series) and NRL matches, 1000-yard target shooting at Camp Perry, military sniper doping with DOPE cards, F-Class and benchrest competition, hunting across open terrain, and ballistic solver apps like Strelok, Hornady 4DOF and Applied Ballistics.

FAQ

Why does a tailwind barely deflect the bullet? What matters is the crosswind component, which is the sin of the wind angle. Wind blowing at 0° or 180° counts as "no-value" because only the lateral part of it can push the bullet off course.

How much does BC reduce drift? As a rough rule, doubling the BC trims flight time and drift by about 30-40% at long range. The bullet holds onto its supersonic speed for longer and clears the wind faster.

When does Coriolis matter? Once you pass roughly 800-1000 yards. The size of the effect depends on your latitude and azimuth, and it can nudge the point of impact by several inches. Modern solvers fold it in for you.