| Cartridge | Typical BC (G1) | Muzzle Velocity | Drop at 300yd | Supersonic Range |
|---|---|---|---|---|
| 5.56 NATO 55gr M193 | 0.243 | 3240 fps | -12" | 800 yards |
| 5.56 NATO 77gr Mk262 | 0.372 | 2750 fps | -15" | 1000+ yards |
| .300 BLK 125gr Super | 0.283 | 2200 fps | -25" | 450 yards |
| 6.5 Grendel 123gr | 0.510 | 2580 fps | -13" | 1100 yards |
| .308 Win 175gr SMK | 0.505 | 2600 fps | -12" | 1200+ yards |
Ballistics Calculator: Drop, Drift & Trajectory
Physics-based trajectory calculator for AR-15 and rifle cartridges. Compute bullet drop, wind drift, time of flight, and energy retention from 0-1000 yards with environmental corrections for altitude, temperature, and humidity.
Before You Read
This guide assumes familiarity with these topics:
What is External Ballistics?
External ballistics is the study of bullet behavior after leaving the barrel. Once the projectile exits the muzzle, it's subject to gravity, air resistance, and wind. These forces cause the bullet to drop below your line of sight and drift laterally in crosswinds.Understanding these forces lets you predict where your bullet will impact at any distance. This knowledge is essential for making accurate shots beyond close range, whether you're shooting steel at 300 yards or hunting at 400.Understanding Ballistic Coefficient (BC)
The ballistic coefficient measures how well a bullet resists air drag. A higher BCBC[Ballistics]Ballistic Coefficient. A measure of how well a bullet cuts through the air. Higher numbers mean less drag and better long-range performance. means the bullet retains velocity better, drops less, and drifts less in wind. BCBC[Ballistics]Ballistic Coefficient. A measure of how well a bullet cuts through the air. Higher numbers mean less drag and better long-range performance. depends on bullet weight, diameter, and shape.G1 vs G7 Drag Models
Bullets are compared against standard projectile shapes. G1 is the traditional reference based on a flat-base bullet from the 1800s. G7 is based on a modern boat-tail bullet and is more accurate for today's projectiles.- G1: Most commonly published. Works well for flat-base and shorter-range calculations. Most manufacturer specs use G1.
- G7: More accurate for boat-tail bullets at extended range. Better models transonic/supersonic transition. Preferred by precision shooters.
Environmental Factors
Air density affects how much drag the bullet experiences. Lower air density means less drag, so the bullet retains velocity better and drops less.Altitude
Higher altitude means lower air pressure and density. At 5,000 feet, air density is about 85% of sea level. This reduces drag and can change your drop by several inches at long range. Shooters in Denver or Salt Lake City will notice their rifles shoot flatter than at sea level.Temperature
Hot air is less dense than cold air. A 40-degree temperature swing can change point of impact by 1-2 inches at 300 yards. If you zero at 70F, expect to shoot slightly high on a 100F summer day and low in 30F winter conditions.Humidity
Water vapor is lighter than the nitrogen and oxygen it displaces, so humid air is actually less dense. However, the effect is small—typically less than 1% change in air density. You can usually ignore humidity unless you're doing precision work at extreme range.Ballistics Calculator
Calculate bullet drop, wind drift, and trajectory from 0-1000 yards. Select a preset ammunition profile or enter custom ballistic data.
Ammunition
BC: 0.243 (G1)
Velocity: 3240 fps
Weight: 55 gr
Standard military ball ammunition. High velocity, velocity-dependent fragmentation.
Zero Settings
Environment
Wind
Right Crosswind at 10 mph
Trajectory Table
| Range | Vel | Energy | TOF | Drop | MOA | Drift | MOA |
|---|---|---|---|---|---|---|---|
| 0 yd | 3240 | 1282 | 0.000s | -2.5" | 0.0 | 0.0" | 0.0 |
| 50 yd | 3060 | 1143 | 0.048s | -0.8" | 1.5 | +0.2" | 0.4 |
| 100 yd | 2878 | 1011 | 0.098s | 0.0" | 0.0 | +1.0" | 0.9 |
| 150 yd | 2694 | 886 | 0.152s | -0.3" | 0.2 | +2.3" | 1.5 |
| 200 yd | 2508 | 768 | 0.210s | -1.7" | 0.8 | +4.3" | 2.1 |
| 250 yd | 2320 | 657 | 0.272s | -4.6" | 1.8 | +7.1" | 2.7 |
| 300 yd | 2128 | 553 | 0.339s | -9.1" | 2.9 | +10.8" | 3.5 |
| 350 yd | 1921 | 450 | 0.413s | -15.5" | 4.2 | +15.7" | 4.3 |
| 400 yd | 1695 | 351 | 0.496s | -24.2" | 5.8 | +22.2" | 5.3 |
| 450 yd | 1451 | 257 | 0.592s | -36.1" | 7.7 | +30.9" | 6.5 |
| 500 yd | 1133 | 157 | 0.708s | -52.2" | 10.0 | +43.1" | 8.2 |
| 550 yd | 897 | 98 | 0.858s | -75.1" | 13.0 | +61.4" | 10.7 |
Trajectory Chart
Line of sight = 0". Drop shown in inches.
Range in yards. Blue dot = zero distance (100 yd).
Using Your Ballistic Data
Holdover vs Turret Adjustments
There are two ways to compensate for bullet drop: hold over the target with your reticle, or dial your turret to move the point of impact up.- Holdovers: Faster for dynamic shooting. Use BDC reticle marks or estimate hold based on target size. Works best inside 400 yards where drops are manageable.
- Turret adjustments: More precise. Dial the exact MOA/MRAD correction and aim center. Essential for precision work beyond 400 yards.
MOA vs MRAD
Both are angular measurements used to quantify adjustments. Neither is inherently better—choose based on your optic.- MOA (Minute of Angle): 1 MOA = 1.047" at 100 yards (roughly 1" per 100 yards). Common on American scopes. Typical clicks: 1/4 MOA or 1/2 MOA.
- MRAD (Milliradian): 1 MRAD = 3.6" at 100 yards. Popular in military and long-range precision. Typical clicks: 0.1 MRAD. Math is simpler (base-10 system).
Creating a Dope Card
A "dope card" is a quick-reference chart of your drop and drift corrections at various distances. Use the calculator above to generate your data, then record it on a card taped to your stock or stored in a scope cover.Verify your calculated dope at the range. Real-world performance may vary slightly from calculated values due to lot-to-lot ammo variation, chronograph accuracy, and shooting conditions.Limitations & Accuracy
This calculator uses a point-mass trajectory model with atmospheric corrections. It provides accurate predictions for most shooting scenarios but has limitations:- Doesn't account for spin drift (significant only beyond 800+ yards)
- Doesn't model Coriolis effect (relevant only for extreme long range 1000+ yards)
- Assumes constant wind speed and direction (real wind is variable)
- BC values are approximations—actual performance varies by lot
Next Step
Ready to continue? Here's the recommended next guide:
How to Zero AR-15 Optics: Red Dots, Irons & LPVOs
Master optic zeroing with step-by-step process for iron sights, red dots, and LPVOs. Includes range prep checklists, mechanical offset tips, and confirmation drills.
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