I have been shooting PRS for three years all my ranges in Wisconsin are within 400 feet of altitude. So I am wondering how important is density altitude? I use the Strelock pro and I use all the weather in puts at the range several times a day during a match but am wondering do others use a density altitude calculator then enter the result in the Strelock.

Density Altitude is a combination of Air Pressure, Temperature, and Humidity. It's basically a "altitude" number under Standard Conditions.

It's the only time we consider humidity when talking shooting

DA is where the bullet "thinks" it is flying

temperature is a factor built-in but also temperature has a separate component

If you use DA you use DA, so in zeroing it would be the DA at that time. Why we zero at 100 yards is because the external conditions do not have a noticeable factor, it's too short of a distance to have time to work on the bullet.

You gather your dope as normal recording the DA, then you use that particular DOPE when you experience the same values.

Data on Previous Engagement or DOPE

You do everything normal, you just match the DOPE to the DA, then when you see that same DA again you use it.

Only every 1000ft matters, you can round up or down, 5500= 6000ft DA etc

DA can be is huge under the right conditions and at distance.  Playing with a ballistic calculator as you're doing will help you to understand the limitations of your system. When you see questions posed about "effective range for a 308" posted here, DA makes a huge difference. What a guy in Vegas can do with a 24" 308 is a LOT different than what the same guy can do with a 20" 308 in Iowa.

USGILT makes a lot of good points.

Most of the time I shoot at 4400' elevation but the temperature swings can be 30+ degrees.  You can start out on a day like today at 65 degrees, and by noon it will be in the 80s and climbing. Inside of 500, it doesn't make a big difference, but when shooting my 223 beyond 800 there can be as much as a 12" variance.  Add in powder sensitivity and it can get interesting.

Last winter I was shooting down in southern Alabama on a cool morning and saw a DA of -700

It made a huge difference.

thank you gentleman for the feedback it helps a lot i found a DA converter i am going to try using the DA this weekend at a PRS shoot!