Wind Drift Calculator
Crosswind drift at a given range, using the standard lag-time method.
How this works
The lag-time method treats wind drift as a byproduct of the bullet slowing down. A bullet that faced no drag would arrive slightly sooner than one that did — that time difference (the "lag") is how long the crosswind has to push sideways on a bullet that is, in effect, running behind schedule. Multiply that lag time by the crosswind's sideways component and you get the drift in inches.
Full value vs. half value wind
A wind blowing straight across your line of fire (90°) produces full drift; a wind blowing straight down or up your line of fire (0° or 180°) produces none. Anything in between scales by the sine of the angle — which is why shooters often call a wind at roughly 30–45° off-axis a "half value" wind, though the true fraction depends on the exact angle.
Frequently asked questions
What wind angle gives the most drift?
A full 90-degree crosswind (blowing directly across your line of fire) produces the maximum drift for a given wind speed. Wind blowing straight down or up your line of fire (0° or 180°) produces essentially none.
What's a "half value" wind?
It's a wind blowing at roughly 30–45 degrees off your line of fire — shooters call it half value because it pushes noticeably less than a full crosswind, though the exact fraction follows the sine of the angle rather than a flat 50%.
Why does a heavier bullet drift less in the same wind?
A heavier, higher-BC bullet resists deceleration better, which means less time lag between it and a theoretical drag-free bullet — and since wind drift comes from that lag, less lag means less drift.
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