DENSITY ALTITUDE
Enter today's conditions and see how far your elevation hold moves from your card.
Baseline
Standard conditions are 59 °F, 29.92 inHg and 50 percent humidity, 100 to 1,000 yd. Sign in to compare against your saved dope card
Baseline density altitude: 127 ft (59 °F, 29.92 inHg, 50 % humidity)
Conditions now
- Density altitude
- 127 ft
- Pressure altitude
- 1 ft
- Station pressure used
- 29.92 inHg
- Air density
- 99.7% of standard
How your dope shifts
At 800 yd you need about the same elevation as your card (DA 127 ft on the card, 127 ft now).
| Range | Card mil | Now mil | Change mil | Change MOA | Wind mil | Wind MOA |
|---|---|---|---|---|---|---|
| 100 | 0.0 | 0.0 | 0.00 | 0.00 | 0.2 | 0.6 |
| 200 | 0.5 | 0.5 | 0.00 | 0.00 | 0.3 | 1.1 |
| 300 | 1.3 | 1.3 | 0.00 | 0.00 | 0.5 | 1.6 |
| 400 | 2.1 | 2.1 | 0.00 | 0.00 | 0.7 | 2.2 |
| 500 | 3.0 | 3.0 | 0.00 | 0.00 | 0.8 | 2.9 |
| 600 | 4.0 | 4.0 | 0.00 | 0.00 | 1.0 | 3.5 |
| 700 | 5.1 | 5.1 | 0.00 | 0.00 | 1.2 | 4.3 |
| 800 | 6.2 | 6.2 | 0.00 | 0.00 | 1.5 | 5.0 |
| 900 | 7.5 | 7.5 | 0.00 | 0.00 | 1.7 | 5.9 |
| 1000 | 9.0 | 9.0 | 0.00 | 0.00 | 2.0 | 6.7 |
A negative change means less elevation than the card. Wind uses the card's wind setting (10 mph at 90 degrees).
True your muzzle velocity (optional)
If you saw a hold at one long range, this finds the muzzle velocity that explains it. Use a range where the bullet is still supersonic.
What density altitude is
Density altitude is the height in a standard atmosphere that has the same air density as you have right now. Hot air, low pressure and humid air are all thinner. Thinner air slows a bullet less, so it drops less and drifts less. The same rifle needs less elevation on a hot summer afternoon, or in the mountains, than it does on a cold morning at the coast. Your card is only right for the day it was made.
The math uses the US National Weather Service formulas for vapor pressure, virtual temperature, density altitude, pressure altitude and station pressure. The solver is the same one the drop calculator uses.