![]() Sea-level Barometric Pressure (inHg) – (Physical Altitude (ft) ÷ 1000) = Approximate Station Pressureįor example, the weather man tells you that the barometric pressure near you is 30.14 inches and you know that you are at an altitude of 3,500 feet.ģ0.14 – (3500 ÷ 1000) = 30.14 – 3.5 = 26.64inHg In this formula, if you know the sea-level barometric pressure (what the weather channel gives you), you can approximate your Station Pressure. These formulas will give you an APPROXIMATE Station Pressure and so they aren’t perfect but they are better than nothing. you have NO way of getting an accurate SP using a watch, mobile phone or other electronic device. **Now, I mentioned a couple of formulas that you can use so that in a “worse case” scenario (i.e. This is WRONG and although it might be close (by mere chance) on occasion, it is likely you will end up with an incorrect DA figure more often than not. I see guys using similar cards who simply read the Pressure Altitude as their ACTUAL altitude/elevation. ![]() *By PROPERLY, I mean don’t skip the step where you ascertain your Pressure Altitude! That’s it! You now have your approximate DA and can reference your DA Dope cards so you can make a shot! Use the SP to PA Chart to ascertain your Pressure Altitude once you have your Station Pressure (Metric version shown). Now that you have established a point where you temperature and pressure altitude intersect, simply track horizontally until you reach the Density Altitude Axis and read off you DA from there.For example, if your Pressure Altitude is 500ft, you would track up until you were halfway between 0ft and 1000ft. If your Pressure Altitude is “between the lines” you simply judge an approximate point between the two lines. Follow an imaginary line up from the bottom of the chart in line with the current temperature at your location until you reach the approximate Pressure Altitude.Reference the Station Pressure reading you got from your watch or formula to the nearest Station Pressure reading on the Station Pressure to Pressure Altitude Chart to establish your Pressure Altitude.Alternatively you can use a couple of formulas** that will give you an “approximate” Station Pressure so you at least be “in the ballpark”. Many modern watches and phones will have this function. Ascertain Station Pressure using a watch or mobile phone.Here are the steps to use the DA card PROPERLY*: ![]() #Density altitude calculator download#Our DA card is available in an Imperial version (Altitude in feet and Temperature in ☏) and in a Metric version (Altitude in meters and Temperature in ☌) and the download link is at the very bottom of this article. ![]() These can be produced at home on your computer, printed and laminated ready for use.Ĭlick Here To Download The Density Altitude Cardīut there is one slight problem…how do you calculate DA without a Kestrel? So…in this situation, the next best thing is to use DOPE cards that are referenced to density altitude. Now, having a Kestrel is great and all, but for some people its just to much $$$ to lay down in an already expensive hobby. ![]() To shoot accurately at long range, you need to know what the environmental conditions are…specifically what the Density Altitude (DA) is because the DA is the true representation of what the bullet is flying through. The Density Altitude Graph is available for Imperial AND Metric Users. ![]()
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