Effective Range Calculator
How far a load still does its job: where the bullet stops expanding, where the energy falls below what you need, where the wind moves it further than the target is wide, and which of those runs out first.
- Load
- .308 Winchester, 168 gr at 2,700 ft/s, G7 0.263, zeroed at 200 yd
- Needed of it
- 1,800 ft/s to expand, 1,000 ft·lb on arrival, inside 6" of drift
The wind is what runs out first here. A wind call is a judgment, not a measurement, so treat this as the distance beyond which a bad call costs you the shot.
The two thresholds are yours to set. Bullet makers publish an expansion velocity for their own bullets and it differs by construction; where a jurisdiction sets a minimum energy for game, that is the number that counts.
Effective range is not the distance you can hit at. It is the distance beyond which the load stops doing its job even when you do yours.
What runs out, and where
the shortest of these is the one that sets the range| What runs out | At |
|---|---|
| Arrives slower than 1800 ft/s1801 ft/s at 568 yd | 568 yd |
| Carries less than 1000 ft·lb1001 ft·lb at 686 yd | 686 yd |
| Wind moves it more than 6"-6.0" in a 10 mph wind at 292 yd | 292 yd |
| Falls through the speed of soundstill supersonic at the far end | — |
| Needs holdover to stay on the targetwith a 269 yd zero, inside a 8" target | 314 yd |
Against range
the line is the threshold; the marker is where the load stops doing its jobThe flight
every hundred yards to the far end| Range | Velocity | Energy | Drop | Drift |
|---|---|---|---|---|
| 100 yd | 2,527 ft/s | 2,382 ft·lb | 1.4" | -0.7" |
| 200 yd | 2,360 ft/s | 2,078 ft·lb | -0.0" | -2.7" |
| 300 yd | 2,200 ft/s | 1,805 ft·lb | -7.7" | -6.3" |
| 400 yd | 2,046 ft/s | 1,562 ft·lb | -22.5" | -11.7" |
| 500 yd | 1,899 ft/s | 1,345 ft·lb | -45.7" | -18.9" |
| 600 yd | 1,756 ft/s | 1,151 ft·lb | -78.6" | -28.3" |
| 700 yd | 1,619 ft/s | 978 ft·lb | -122.7" | -40.0" |
| 800 yd | 1,486 ft/s | 824 ft·lb | -180.2" | -54.5" |
How this is worked out
Effective range is not one number, because "effective" means several things that run out at different distances. The bullet slows until it no longer opens up on impact. The energy it carries falls under whatever you have decided is enough. The wind moves it further than the target is wide, so a mediocre wind call costs you the shot. And somewhere out there it falls through the speed of sound, where groups usually open up. This works out each of those along the same flight and reports the shortest, because the shortest is the one that decides.
The flight itself is the zero calculator's: the same point-mass solution, the same standard drag tables, the same library of loads, checked against 212 manufacturer tables. Nothing about the physics is new here. What is new is asking a different question of the same curve.
The example on this page is a 168 grain .308 match load at 2,700 feet per second with a 200 yard zero, in a 10 mph crosswind, asked to arrive above 1,800 ft/s and 1,000 ft·lb and to stay inside 6 inches of drift. It runs out at 292 yards, and the thing that runs out is this: wind moves it more than 6".
Two of the numbers are yours rather than ours, and that is deliberate. Bullet makers publish an impact velocity below which their own bullets stop expanding reliably, and it differs by construction: a monolithic copper bullet opens lower than a tough bonded one. Where a jurisdiction sets a minimum energy for game, that is the number that counts. This tool does not supply either as a fact. It tells you where your load falls below the numbers you chose.
How to use it
- Pick the cartridge and the load, or type your own chronographed velocity over it.
- Set the expansion velocity from your bullet maker's own figure. It is usually on the product page, and it matters more than anything else here.
- Set the energy you want on arrival, and how much wind drift you will accept.
- Read which limit runs out first. That is the number, and the others tell you what you would have to change to move it.
What it assumes
- The trajectory is the same point-mass solution the zero calculator uses, on the standard drag tables, and it carries the same assumptions: no spin drift, no Coriolis, level ground.
- The expansion velocity and the minimum energy are yours to set. They are not published standards and this tool does not supply them as facts; it answers where the load falls below the numbers you chose.
- Energy is a convenient number, not a measure of what a bullet does to an animal. A bullet that opens properly at 1,200 ft·lb beats one that does not at 1,800.
- Wind drift assumes one steady wind along the whole flight, which is almost never what is there.
- Nothing here says anything about whether a shot is ethical or legal. That is the shooter’s judgment and the jurisdiction’s rules.
Sources
- G1 drag function (mcg1.txt): drag coefficient against Mach number for the standard G1 projectile — US Army Ballistic Research Laboratory, via JBM Ballistics (checked 2026-09-27)
- G7 drag function (mcg7.txt): drag coefficient against Mach number for the standard G7 projectile — US Army Ballistic Research Laboratory, via JBM Ballistics (checked 2026-09-27)
- Manual of the ICAO Standard Atmosphere (Doc 7488): sea-level constants and the temperature lapse rate — International Civil Aviation Organization (checked 2026-09-27)
- Modern Exterior Ballistics, chapter 5: the point-mass trajectory and the ballistic coefficient — Robert L. McCoy, Schiffer (checked 2026-09-27)