What is “Density Altitude?"

by
posted on August 8, 2012
bs_2015_fs.jpg (16)

The Background
As more and more hunters and shooters explore the complexities of long range shooting, factors like barometric pressure, altitude, and humidity have all the sudden entered into the shooting equation. At most hunting distances, none of these things matter: range, angle, and wind are the only real external factors that will cause a miss in the first 300 or so yards.

The Question
I recently had a chance to try out a Kestrel 4000 wind meter (available from Sinclair) that provides the shooter with, among other things, a density altitude reading. As if calculating this stuff wasn’t confusing enough, what in the heck is “density altitude”?

The Expert Deferral
We reached out to our friend Paul “The Rocket Scientist,” who is literally a scientist who spent his career working on things like missile guidance systems. He’s also a long-range rifle shooter. His verbatim answer:

Density altitude X is the altitude that, on a day with standard pressure and standard temperature, would have a geographic altitude of X. In hot weather the density altitude is always higher (i.e., less dense) than the geographic altitude (from a topo map or GPS) because the temperature is always hotter than a standard day. Conversely for a cold day. Washington, D.C. at 100F has a density altitude of about 2700 ft even though the geographic altitude (the real altitude of the dirt) is very close to sea level. What really matters to the bullet is the actual density, usually measured in pounds per cubic feet. Sea level standard day (59F) is 0.075lb/cubic foot. But for every combination of pressure, temperature and humidity (ignore for practical purposes) there is a unique density and therefore a unique density altitude.

The Layperson’s Translation (I hope)
Density altitude is the altitude that actually matters in the context of shooting. When calculating a bullet’s path, the density altitude should be used in the equation if it is available.

Latest

NRA ILA Lede
NRA ILA Lede

NRA Files Lawsuit Challenging Colorado’s Excise Tax on Firearm and Ammunition Sales

On March 31, the National Rifle Association of America (NRA), together with the Firearms Policy Coalition, Second Amendment Foundation, Colorado State Shooting Association, Magnum Shooting Center and an NRA member, filed a lawsuit challenging Colorado’s 6.5-percent excise tax on the retail sale of firearms, firearm precursor parts and ammunition.

The Magnum Research 10mm Magnum BFR Revolver

This 6-shot, single-action revolver may well be the first factory-made handgun chambered in this caliber in over three decades.

Hunting Heritage Trust Grant Applications Being Accepted

The National Shooting Sports Foundation (NSSF), the trade association for the firearm industry, has opened the application period for the 2025 Hunting Heritage Trust Grants. They offer a total of $100,000 in financial support for programs that work to expand participation in hunting and the shooting sports.

Hardware Review: Marlin Model 1895 Dark

If you think lever-action rifles should only have walnut stocks and a blued-metal finish, then the new Marlin Dark series with its polymer buttstock and aluminum AR-esque handguard probably won’t be your thing. That’s a shame, because this recent offering in Marlin’s line of modernized, capable lever-action rifles has a lot going for it in terms of performance, functionality and fun.

ATN Shipping TICO LTV Thermal Clip-On

This thermal clip-on device is a huge night-time gear multiplier for hunters and observers, transforming any daytime scope into a thermal sight.

MidwayUSA Named Official Sponsor of the 2025 NRA Annual Meetings

Glock, Inc. is the Presenting Sponsor of the Freedom Experience on Saturday, April 26th

Interests



Get the best of American Hunter delivered to your inbox.