crash coarse in Density Altitude
When we talk about shooting really far, most shooters will obsess over one number:
Elevation.
The problem is… your bullet doesn’t care about your GPS elevation. It cares about air density.
The atmosphere your bullet flies through is constantly changing. Temperature, pressure, and humidity all affect drag, and drag directly affects drop.
The way we measure that combined effect is Density Altitude (DA).
Around here, we often call it Station Pressure Conditions — meaning the air you’re physically standing in when you press the trigger.
What Density Altitude Actually Means
Density Altitude is the altitude your bullet thinks it’s shooting at.
Higher DA = Thinner air
Lower DA = Thicker air
Thin air means:
• Less drag
• Flatter trajectory
• Less elevation needed
Dense air means:
• More drag
• More drop
• More elevation needed
Two days at the same range can shoot completely differently if DA changes.
Why Station Pressure Matters
Most weather apps give you barometric pressure corrected to sea level. That number is great for meteorologists… not great for shooters.
We care about Station Pressure — the actual pressure at your firing position.
That’s the pressure your bullet feels when it leaves the rifle.
How To Calculate Density Altitude
You can get DA directly from a Kestrel or ballistic solver (if you have one), but understanding how it’s calculated helps you trust your data.
Step 1 — Pressure Altitude
Pressure Altitude = (29.92 − Station Pressure) × 1000 + Elevation (ft)
Step 2 — Density Altitude
Density Altitude = Pressure Altitude + [120 × (OAT − ISA Temp)]
Where:
- OAT = Outside Air Temp (°C)
• ISA Temp = Standard temp at your elevation
ISA Temp is roughly:
15°C − (2°C per 1,000 ft elevation)
Example — Cold Day
Location:
• Elevation: 4,000 ft
• Station Pressure: 29.50 inHg
• Temp: 5°C
Pressure Altitude:
(29.92 − 29.50) × 1000 + 4000
= 4,420 ft
ISA Temp:
15 − (2 × 4) = 7°C
Density Altitude:
4,420 + [120 × (5 − 7)]
4,420 − 240
= 4,180 ft DA
Your bullet behaves like it’s shooting at 4,180 ft.
Example — Hot Day (Same Range)
Same location, new conditions:
- Temp: 30°C
Density Altitude:
4,420 + [120 × (30 − 7)]
4,420 + 2,760
= 7,180 ft DA
Same rifle. Same ammo. Same shooter.
Over 3,000 ft difference in how your bullet flies.
Once you start logging data this way, your firing solutions travel with you anywhere.
The Bottom Line
If you want consistent hits at distance:
Stop tracking where you are.
Start tracking what the air is doing.
Your rifle shoots through atmosphere, not topography.
