External Ballistics Calculator

This calculator's drag model derives velocity decay purely from the Ballistic Coefficient and air density, without a separate mass term -- real-world ballistic coefficients already fold a bullet's weight, diameter, and shape into a single number, which is why changing Bullet Weight here (holding Ballistic Coefficient fixed) doesn't move the trajectory. Bullet Weight only affects Energy at Target and Muzzle Energy, both of which are calculated directly from velocity squared times weight.

Zero Range is the distance at which your scope's line of sight and the bullet's actual path are calibrated to intersect -- that's the definition of "zeroing" a rifle. This calculator solves for the bore's slight upward tilt needed to make that crossing happen at exactly your declared Zero Range, so Drop at Target is always 0 there by construction, not by coincidence. 100 yards -- this calculator's Target Range minimum, matching the lowest allowed Zero Range -- is also why: inside your actual Zero Range, a rifle's true path briefly rises above the line of sight before crossing back down to zero, real ballistic behavior caused by that same bore tilt, which would make Drop at Target rise and fall rather than fall steadily as Target Range increases. This calculator doesn't model that closer-in rise, so it only reports figures at or beyond the zero distance.

Both a higher Muzzle Velocity and a higher Ballistic Coefficient mean the bullet retains more of its speed as it travels, which shortens Time of Flight to any given Target Range. Less time in flight means less time for gravity to pull the bullet down, so the trajectory stays flatter and Drop at Target shrinks in magnitude as either input increases, for the target ranges at or beyond your Zero Range that this calculator covers.

Both adjust the modeled air density that the bullet has to push through: colder temperatures and lower altitudes mean denser air, which increases effective drag and slows the bullet faster, steepening the trajectory. Warmer temperatures and higher altitudes have the opposite effect, thinning the air and letting the bullet retain velocity -- and therefore a flatter path -- over a longer distance.

This uses a simplified single-exponential drag approximation rather than a true G1/G7 drag-table lookup or a full physics simulation, so treat its trajectory, velocity, and energy figures as directional estimates for comparing scenarios (different calibers, zero distances, or conditions) rather than exact dial-in numbers. For an actual field zero, always confirm point of impact by shooting your specific rifle and load at the ranges that matter to you.