Free Ballistic Calculator: Bullet Drop, Wind Holds & Ballistic Tables

External ballistics is the study of a projectile's flight from the moment it leaves the muzzle until it reaches the target. Once the bullet exits the bore, two forces dominate its trajectory: gravity, which is constant and predictable, and aerodynamic drag, which is neither simple nor linear.

Drag is modeled using a drag coefficient curve referenced against a standard projectile shape. The two dominant models in practical use are G1 and G7. G1 references a flat-base, blunt-nosed standard and was historically dominant, most older manufacturer BC tables are G1. G7 references a long, boat-tail, tangent-ogive projectile that closely matches modern match and hunting bullets. For any bullet with a boat-tail and a secant or hybrid ogive, the G7 BC will produce a more accurate drag curve, particularly at extended ranges where the G1 curve diverges from reality. Use G7 for modern precision rifle bullets; use G1 if that is the only value the manufacturer publishes.

The ballistic coefficient (BC) quantifies how efficiently a bullet overcomes drag relative to the standard projectile. Higher BC means less deceleration for a given atmospheric density. Atmospheric density, driven by altitude, temperature, and pressure, scales the drag force directly: lower density means less drag and a flatter trajectory.

Muzzle velocity is the single largest variable affecting drop. A 50 fps difference in MV shifts your 800-yard drop more than almost any other input change.

This calculator uses a point-mass (3DOF) model, sometimes called the Pejsa or modified point-mass approach, appropriate for a web tool and accurate for most practical shooting inside 800 yards. A full 6DOF solver, as used in Atlas Ballistics, additionally models spin drift, aerodynamic jump, and Coriolis acceleration, effects that become consequential beyond roughly 600 yards in match-grade precision contexts.

Drop in the table is measured from the line of bore extended, not from the line of sight. At your zero range, the bullet's path crosses the line of sight; the drop column will show a value near zero at that distance (residual inches from the bore offset, not from the crosshair). Beyond zero, drop increases with gravity and drag. Do not confuse raw drop with the hold, your hold is the angular correction required to bring the bullet back to point of aim, which is what the MOA and MRAD columns express.

MOA vs MRAD: 1 MOA equals approximately 1.047 inches at 100 yards, most shooters round to 1 inch per 100 yd for field math. 1 MRAD equals exactly 3.6 inches at 100 yards, or 36 inches at 1000 yards. Match your output units to your scope's turret graduation. If your scope clicks in 0.1 MRAD increments, use the MRAD column. If it clicks in ¼ MOA, use MOA. Mixing systems causes errors.

Wind holds require knowing the effective wind value based on clock angle. Use cosine of the wind angle off the bore line as the multiplier:

• 12 or 6 o'clock (headwind or tailwind): zero value
• 3 or 9 o'clock (full crosswind): full value (multiplier = 1.0)
• 1:30, 4:30, 7:30, 10:30 (45° oblique): approximately half value (multiplier ≈ 0.71)

Time of flight is the correct multiplier for wind sensitivity, a bullet that spends more time in the air is subject to more wind impulse regardless of its remaining energy. A slower, heavier bullet may retain more energy at impact but drift more in wind than a faster, lighter one.

Worked example, 6.5 Creedmoor, 140 gr Berger Hybrid, G7 BC 0.315, 2700 fps MV, 100 yd zero, 10 mph 90° crosswind, 500 yd target: The calculator should return approximately 44 inches of drop (~8.4 MOA / ~2.4 MRAD) and approximately 11 inches of wind drift (~2.1 MOA / ~0.6 MRAD). Run those inputs above to verify against your specific atmospheric conditions. These are modeled values, field truing against actual impacts is essential before trusting any solution at distance.

Manufacturer-published BC values are almost universally optimistic. They are typically measured at short range, averaged across a wide velocity band, and tested under controlled conditions that do not match your barrel, your lot of ammunition, or your environment. The result: at 600 yards the predicted drop may be 2–4 inches high relative to actual impact, and at 1000 yards that error can exceed 10 inches, well outside a 10-inch steel plate.

Truing is the process of correcting your ballistic solution against real-world impacts. There are two methods:

• BC truing: Hold muzzle velocity fixed at your measured or chronographed value and adjust BC until the predicted drop matches observed impact at a known distance. This is appropriate when you have confidence in your MV measurement.
• Velocity truing: Hold BC fixed (ideally a Doppler-derived value) and adjust MV until the curve fits. This is appropriate when your MV is less certain than your BC.

The two corrections shift the trajectory curve differently. BC truing changes the shape of the drop curve, the effect compounds with range. Velocity truing shifts the curve more uniformly. In practice, most shooters apply a velocity correction because it is numerically simpler, but BC truing is more physically accurate when using radar-verified drag data.

Always true at the longest range you can shoot, not at 100 yards. A 100-yard group tells you almost nothing about the shape of your trajectory curve, the errors are too small to distinguish from dispersion. Shoot at 500, 800, and 1000 yards, record actual vs. predicted, and back-calculate your correction.

Doppler radar-derived BCs, available from sources like Hornady's 4DOF data or manufacturer radar campaigns, are the best starting point because they capture the actual drag curve across the entire velocity envelope rather than a single averaged BC.

Atlas Ballistics includes a built-in truing workflow: log actual impacts from your shot log, compare to the predicted solution, and the app auto-corrects BC or MV across the full range card. That closes the loop between the table and the target. Download Atlas Ballistics to run your truing workflow at the range, not back at the desk.

Density altitude (DA) is the single number that encapsulates the combined effect of elevation, temperature, and barometric pressure on air density. Higher DA means lower air density, which means less drag, bullets fly flatter and faster than at sea level standard conditions.

A load zeroed at sea level on a standard day will strike high at elevation because the bullet experiences less drag deceleration. The magnitude is not trivial: the same load with a 100-yard zero, comparing sea level to a 5000-foot density altitude, can differ by more than 2 MOA at 800 yards. In practical terms, that is 16 inches at distance, a clean miss on an 18-inch plate and a likely wound rather than a clean kill on game.

The calculator asks for altitude, temperature, and barometric pressure separately because DA is derived from all three. If you enter only altitude, you are assuming standard temperature and pressure for that altitude, an assumption that fails in summer heat, approaching weather systems, or high-pressure ridges. Enter all three for an accurate atmospheric correction.

Humidity has a counterintuitive effect: humid air is slightly less dense than dry air at the same temperature and pressure, because water vapor (molecular weight 18) displaces heavier nitrogen (28) and oxygen (32) molecules. The practical effect on trajectory is small, typically less than 0.5 MOA at 1000 yards, but it operates in the direction opposite to what most shooters assume. The calculator accounts for it when you enter relative humidity.

Using ICAO standard atmosphere (the default) is appropriate for building a baseline DOPE card or comparing loads on paper. For any field application, a PRS stage, a hunting shot in the Rockies in August, or a match at altitude, override all three atmospheric inputs with actual conditions. The fields are there for exactly that purpose.

The same ballistic table serves different purposes depending on who is reading it. Understanding what to optimize for avoids applying competition-shooter logic to a hunting context and vice versa.

For hunters:

• Maximum point-blank range (MPBR) is often more useful than a precise dialed solution. MPBR defines the distance at which a bullet, zeroed to stay within a defined vital zone (typically ±3 inches for deer), requires no hold correction. For field shots at unknown range where dialing is impractical, knowing your MPBR keeps you ethical without requiring a rangefinder and turret adjustment.
• Terminal velocity and energy at impact matter for clean kills. Common practical minimums are approximately 1000 ft-lbs for deer-class game and 1500 ft-lbs for elk-class, check the energy column in the table at your expected maximum range.
• Transonic transition is a hard limit for hunting reliability. As bullet velocity drops through approximately 1340 fps, the bullet passes through a region of aerodynamic instability where the bow shock restructures. Group size expands unpredictably. If your table shows the bullet going transonic before it reaches your target, you need either a faster load, a higher-BC bullet, or a shorter engagement range.

For competition and PRS/NRL shooters:

• You need the full table with MRAD holds at 10 or 25-yard increments, the stage card, not just the DOPE for a handful of known distances.
• Spin drift runs right for right-hand-twist barrels. Depending on twist rate and BC, this can reach 0.5–1.5 MRAD at 1000 yards, a meaningful correction on a 10-inch plate at distance.
• Coriolis acceleration is real at 1000 yards and beyond. Its direction and magnitude depend on your latitude and firing azimuth. It is not a fixed correction, it changes every time you change position.
• Aerodynamic jump from a crosswind causes a vertical displacement that is independent of and in addition to the horizontal wind drift.

The free calculator above covers hunting applications and mid-range competition DOPE accurately. Atlas Ballistics adds spin drift, Coriolis, aerodynamic jump, GPS-linked DA, and a stage card builder for competitors who need the full solution.

See the FAQ section below for answers to the most common questions about ballistic calculators, drag models, and getting an accurate firing solution.