Density altitude calculator: by ZIP code, with live weather
Type a ZIP code or tap the map: the calculator reads the nearest weather station and the ground elevation, then gives the density altitude and what it means for your drone. Or type your own values.
Calculate density altitude
Live weather for a spot in the U.S., or the values you type. The answer comes with the pressure altitude, the air density and what that air does to a drone.
Or tap the map. Alaska, Hawaii and Puerto Rico are drawn below the lower 48, at their own scale.
A planning aid: the weather station can be miles away and its reading up to three hours old. Your drone's own limits, and the air where you fly, come first.
How the density altitude calculator works
It needs four values: the elevation, the temperature, the altimeter setting and the dew point. Live, it reads them for your spot; by hand, you type them. The math is the National Weather Service's.
Live weather by ZIP code, place or map tap
Type a ZIP code, a city and state, or coordinates, tap Use my location, or tap the map. The calculator then asks two public services, straight from your browser:
- The National Weather Service for the weather stations around your spot. Of the four nearest within 75 miles, it takes the closest that has sent a temperature and an altimeter setting in the last three hours, with its dew point when there is one. Most are airport stations, the same ones behind the METARs pilots read.
- The U.S. Geological Survey for the ground elevation at your exact spot. If that does not load, it uses the station's elevation and says so.
The answer names the station, how far away it is and how old its reading is, under The values used. When the station sits 1,000 ft or more above or below your spot, the answer says so: air usually cools about 3.5 °F for every 1,000 ft of height, so the temperature where you fly can differ. Edit these values moves every number into the form, so you can type your own temperature and work it out again.
Your spot stays yours
The calculator sends the weather service and the elevation service only your spot's coordinates, rounded to four decimals (about 40 ft), with no cookies. Nothing is stored, and nothing goes in the page address.
Your own values
Under Enter values, enter the elevation in feet, the temperature in °F or °C, the altimeter setting in inches of mercury (or hPa, such as 1013) and, if you have it, the dew point. Nothing is sent anywhere: the math runs on the page, and it works offline.
The steps are the National Weather Service's formulas, the ones the FAA's handbook sends pilots to for humidity (the formula and a worked example are below). They read about 20 ft above the textbook standard atmosphere, because their constants are rounded: on a standard day at sea level the answer is 18 ft, not 0. That is far less than the change from one degree of temperature.
What the answer shows
- Density altitude, in feet, and how it compares with a standard day at that elevation;
- pressure altitude, the height the air pressure alone points to;
- air density as a share of standard sea-level air, and how many feet humidity adds;
- what it means for your drone: lift and thrust, flight time and climb, in plain words.
Check the whole spot
Density altitude is one check. Can I fly here? checks a spot for no-fly zones, airspace, the 400 ft ceiling, wind and daylight.
What is density altitude?
Density altitude is the height in the standard atmosphere where the air is as dense as the air around you. Your aircraft, a drone included, flies as if it were at that height.
The Federal Aviation Administration (FAA) defines it as “the altitude in the standard atmosphere corresponding to a particular value of air density”, and as pressure altitude corrected for nonstandard temperature. The standard atmosphere is the textbook day: 29.92 inches of mercury and 59 °F (15 °C) at sea level, with the temperature falling about 3.5 °F (2 °C) for every 1,000 ft up: the standard lapse rate. On such a day, density altitude and the real elevation are the same. On a hot day, the air is thinner than standard, and the density altitude is higher than the ground.
The handbook's example is a field at 5,048 ft. At its standard temperature of 5 °C (41 °F), the density altitude is 5,048 ft. At 30 °C (86 °F) it is 7,855 ft: an aircraft takes off as if the field were about 2,800 ft higher. At −25 °C (−13 °F) it is 1,232 ft, and the aircraft performs much better.
High density altitude and low density altitude
High density altitude means thin air, and worse performance. It comes from:
- high elevations, such as Denver or a mountain trailhead;
- low air pressure, as when a storm system moves in;
- high temperatures, so summer afternoons are the worst time;
- high humidity, because moist air is lighter than dry air;
- or a mix of these: hot and high, as on a humid summer afternoon in the mountains.
Low density altitude means dense air, and better performance: low elevations, high pressure, cold and dry air. On a cold winter day at sea level the density altitude can drop below zero, shown here with a minus sign.
What density altitude does to a drone
Thin air means less lift and thrust, a shorter flight time and a slower climb. The FAA says high density altitudes may call for less weight before you fly.
A drone holds itself up with its propellers, and a propeller pushes on air: thin air has fewer air molecules in each cubic foot to push. The FAA's handbook says that as air becomes less dense, it reduces power, thrust (“a propeller is less efficient in thin air”) and lift; lift and drag vary directly with the density of the air.
The FAA's advisory circular for Part 107 pilots puts it this way: “high elevations, high air temperatures, and high humidity (high density altitudes) may require a reduction in weight before flight is attempted.” Its preflight checklist asks pilots to review the drone's performance “considering density altitude and wind”.
In practice, for a battery drone
Less lift and thrust
Each turn of the propellers moves less air, so the motors spin faster to hold the same hover.
Shorter flight time
Faster motors draw more current, and the battery runs down sooner. DJI measures its flight times “under conditions equivalent to windless operation and sea-level altitude”, so in thin air, plan on less than the box says.
Slower climb and less reserve
The spare power left for climbing, for a gust or for a payload shrinks. The FAA's remote pilot study guide names takeoff, rate of climb, ceiling, payload and range among the parts of performance that suffer.
How the answer reads your air
- Below 1,000 ft
Normal air. Close to the sea-level air flight times are measured in. Expect normal lift, climb and flight time.
Normal air - 1,000 to 3,000 ft
A little thin. The drone works a little harder to hover; flight time may come in a little under the maker's figure.
A little thin - 3,000 to 6,000 ft
Thin air. Less lift and thrust, a shorter flight time and a slower climb. Land with a bigger battery reserve.
Thin air - 6,000 ft and up
Very thin air. Much less lift and thrust; some drones struggle to take off with a load. Fly light, and check the maximum takeoff altitude in your drone's specs.
Very thin airWhat the FAA says
Although a maximum gross takeoff weight may be specified, the aircraft may not always safely take off with this load under all conditions.
AC 107-2A, Appendix B, B.2.1.1The bands are this calculator's plain-word guide, not FAA limits. Your drone's own specs and the way it flies on the day decide.
The density altitude formula, with a worked example
Five steps: station pressure, pressure altitude, vapor pressure, virtual temperature, then density altitude. Here they are with the FAA handbook's own example: 8,000 ft, 80 °F, dew point 75 °F.
The FAA's Pilot's Handbook of Aeronautical Knowledge works this example with the National Weather Service's density altitude calculator: at 8,000 ft, where the standard pressure is 22.22 inHg, a temperature of 80 °F and a dew point of 75 °F give a density altitude of 11,564 ft. These are the steps, in the NWS formulas this calculator uses, starting from the altimeter setting a weather report gives (29.92 inHg here).
In meters
The steps use feet because U.S. aviation does. For meters, multiply the answer by 0.3048: 11,564 ft is 3,525 m. The calculator takes °C and hPa as typed.
-
1Station pressure
The real air pressure at the ground, from the altimeter setting A and the elevation h in meters (8,000 ft is 2,438.4 m):
P = A × ((288 − 0.0065 × h) / 288)5.256129.92 × (272.15 / 288)5.2561 = 22.22 inHg, or 752.5 hPa: the pressure in millibars, the unit the NWS formulas take (1 hPa is 1 millibar; 1 inHg is 33.8639 hPa).
-
2Pressure altitude
The height that pressure has in the standard atmosphere:
PA = (1 − (PhPa / 1013.25)0.190284) × 145,366.45 ft(1 − (752.5 / 1013.25)0.190284) × 145,366.45 = 8,002 ft.
-
3Vapor pressure of the water in the air
From the dew point Td in °C (75 °F is 23.89 °C):
e = 6.11 × 10(7.5 × Td) / (237.3 + Td)e = 29.65 hPa.
-
4Virtual temperature
The temperature dry air would need to be as light as this moist air, from the temperature T in kelvin (80 °F is 299.82 K):
Tv = T / (1 − (e / PhPa) × (1 − 0.622))299.82 / (1 − (29.65 / 752.5) × 0.378) = 304.35 K, which is 547.83 °R (kelvin × 1.8).
-
5Density altitude
From the station pressure in inHg and the virtual temperature in degrees Rankine:
DA = 145,366 × (1 − (17.326 × PinHg / Tv,°R)0.235) ft145,366 × (1 − (17.326 × 22.22 / 547.83)0.235) = 11,564 ft, the handbook's answer.
Leave the dew point out and the virtual temperature is just the temperature: the same air, perfectly dry, comes out at 11,092 ft. The handbook: “With no humidity, the density altitude would be almost 500 feet lower.”
Check it yourself
Under Enter values, type 8000 ft, 80 °F, 29.92 and a dew point of 75. The answer is 11,564 ft; leave the dew point empty and it is 11,092 ft.
Pressure altitude and the ISA standard temperature
Pressure altitude is the elevation corrected for the day's air pressure: about 1,000 ft for each inch of mercury the altimeter setting is below 29.92. The standard (ISA) temperature is 15 °C at sea level, minus about 2 °C per 1,000 ft.
How to find pressure altitude
Pressure altitude is the height above the standard datum plane, where the pressure is 29.92 inHg. The FAA gives three ways to get it: set an altimeter to 29.92 and read it; add a correction for the reported altimeter setting to the field elevation; or use a flight computer. The correction is about 1,000 ft per inch of mercury:
pressure altitude ≈ elevation + (29.92 − altimeter setting) × 1,000 ft
The handbook's example: on a field at sea level with an altimeter setting of 29.7, the correction is 205 ft, so the pressure altitude is 205 ft. The exact NWS formula is step 2 above; the calculator uses that.
The FAA's correction table
| Altimeter setting, inHg | Add to the elevation |
|---|---|
| 28.50 | 1,340 ft |
| 29.00 | 863 ft |
| 29.50 | 392 ft |
| 29.70 | 205 ft |
| 29.90 | 20 ft |
| 29.92 | 0 ft |
| 30.00 | −73 ft |
| 30.20 | −257 ft |
| 30.50 | −531 ft |
| 31.00 | −983 ft |
From Figure 11-3 of the handbook, which lists every tenth of an inch from 28.0 to 31.0. A minus sign means subtract.
How to calculate the ISA temperature
The International Standard Atmosphere (ISA) sets 15 °C (59 °F) at sea level and a fall of about 2 °C (3.5 °F) per 1,000 ft, up to 36,000 ft:
ISA temperature ≈ 15 °C − 2 °C × (altitude in ft / 1,000)
At 5,000 ft that is 5 °C (41 °F). The exact lapse is 1.98 °C per 1,000 ft, and the calculator uses it to say how much warmer or colder than standard your air is. The further above standard, the higher the density altitude climbs over the pressure altitude: in the handbook's 5,048 ft example, 25 °C above standard adds about 2,800 ft, some 110 ft for each °C.
How does humidity affect density altitude?
Humid air is lighter than dry air, so humidity raises the density altitude. Usually by a few hundred feet: less than heat or height, but not nothing.
Water vapor is lighter than dry air. In the FAA's words, “as the water content of the air increases, the air becomes less dense, increasing density altitude and decreasing performance.” The handbook adds that humidity alone is usually not considered an important factor, “but it is a contributing factor”, and there are no rules of thumb for it: it is worked out with formulas like the ones above.
The calculator uses the dew point, not the relative humidity, because the dew point is what weather stations report and it says how much water the air holds. On a 90 °F day at sea level with standard pressure:
| Dew point | Density altitude | Humidity adds |
|---|---|---|
| Dry air | 1,990 ft | — |
| 40 °F, a dry day | 2,090 ft | 110 ft |
| 60 °F | 2,210 ft | 220 ft |
| 70 °F, muggy | 2,300 ft | 320 ft |
| 75 °F, very humid | 2,360 ft | 370 ft |
Warm air can hold more water than cold air, so humidity matters most on hot days, which are the days density altitude is already high. A live reading includes the dew point when the station reports one; the answer then says how many feet humidity adds.
Dew point or humidity?
Relative humidity is a share of what the air could hold at its temperature, so it changes as the day warms. The dew point is the temperature at which the air would be saturated; the closer it is to the temperature, the more humid the air.
Density altitude chart by elevation and temperature
Find your elevation on the left and the temperature across the top. The chart assumes the standard altimeter setting, 29.92 inHg, and dry air; for your day's numbers, use the calculator.
Shaded by the calculator’s bands:Below 1,000 ft, normal air1,000 to 3,000 ft, a little thin3,000 to 6,000 ft, thin air6,000 ft and up, very thin air
| Elevation | Standard | 40°F | 60°F | 70°F | 80°F | 90°F | 100°F |
|---|---|---|---|---|---|---|---|
| 0 ft | 59°F | −1,300 | 100 | 700 | 1,400 | 2,000 | 2,600 |
| 1,000 ft | 55°F | 0 | 1,300 | 2,000 | 2,600 | 3,200 | 3,800 |
| 2,000 ft | 52°F | 1,200 | 2,500 | 3,200 | 3,800 | 4,400 | 5,000 |
| 3,000 ft | 48°F | 2,500 | 3,800 | 4,400 | 5,000 | 5,600 | 6,200 |
| 4,000 ft | 45°F | 3,700 | 5,000 | 5,600 | 6,200 | 6,800 | 7,400 |
| 5,000 ft | 41°F | 4,900 | 6,200 | 6,900 | 7,500 | 8,100 | 8,600 |
| 6,000 ft | 38°F | 6,200 | 7,500 | 8,100 | 8,700 | 9,300 | 9,800 |
| 7,000 ft | 34°F | 7,400 | 8,700 | 9,300 | 9,900 | 10,500 | 11,000 |
| 8,000 ft | 30°F | 8,600 | 9,900 | 10,500 | 11,100 | 11,700 | 12,200 |
| 9,000 ft | 27°F | 9,900 | 11,100 | 11,700 | 12,300 | 12,900 | 13,400 |
| 10,000 ft | 23°F | 11,100 | 12,300 | 12,900 | 13,500 | 14,100 | 14,600 |
Worked out with the formulas above and rounded to the nearest 100 ft. “Standard” is the ISA temperature at that elevation. A lower altimeter setting or a humid day raises every number; the handbook's own density altitude chart, Figure 11-4, plots the same thing from pressure altitude and outside air temperature.
Density altitude on the Part 107 test
The FAA's study guide for the remote pilot test covers density altitude in its weather chapter. Know which conditions make it high and what it does to performance.
The FAA's Remote Pilot study guide treats density altitude in its chapter on the effects of weather on small unmanned aircraft performance. The points to know:
- density altitude is the altitude in the standard atmosphere for a given air density;
- high density altitude means thin air; high elevations, low pressure, high temperatures and high humidity cause it;
- as air density decreases, performance decreases: takeoff, rate of climb and payload all suffer;
- density is directly proportional to pressure, and goes the other way with temperature;
- moist air is lighter than dry air, so humidity raises density altitude, but it is a smaller factor.
The test does not ask you to work out the formula; it asks which conditions lead where. Try the density altitude questions in the practice test.
Part 107 practice test
Questions built from the FAA's study materials, with an explanation for each, density altitude and weather among them.
Take the practice testRelated tools and guides
Density altitude is one check before a flight. These cover the rest.
How your drone flies
Range, time and height.
Density altitude questions and answers
What is the density altitude formula?
The National Weather Service's: DA = 145,366 × (1 − (17.326 × P / Tv)0.235) feet, with P the station pressure in inches of mercury and Tv the virtual temperature in degrees Rankine. Getting P and Tv takes the elevation, the altimeter setting, the temperature and the dew point; the five steps are above. For a quick estimate without humidity, start from the pressure altitude and add about 110 ft for each °C (60 ft per °F) above the standard temperature.
How does humidity affect density altitude?
It raises it. Water vapor is lighter than dry air, so humid air is less dense. The FAA's example at 8,000 ft and 80 °F: a 75 °F dew point puts the density altitude almost 500 ft higher than dry air would. On most days the effect is a few hundred feet.
How do I calculate the ISA temperature?
Start at 15 °C (59 °F) at sea level and take off about 2 °C (3.5 °F) per 1,000 ft: at 5,000 ft the ISA temperature is about 5 °C (41 °F), at 10,000 ft about −5 °C (23 °F). The difference between the real temperature and that is what pushes density altitude above or below pressure altitude.
What is the air density at 2,000 feet?
In the standard atmosphere, air at 2,000 ft above sea level has a pressure of 27.82 inHg and a temperature of 51.9 °F, and it is about 94% as dense as standard sea-level air. On a warmer day it is thinner. Above ground level depends on your ground: 2,000 ft over a 5,000 ft plateau is 7,000 ft up, about 81%.
What is the difference between pressure altitude and density altitude?
Pressure altitude corrects the elevation for the day's air pressure only. Density altitude also corrects it for temperature (and here, humidity). On a standard day the two are the same; on a hot day density altitude is higher.
Can I get density altitude by ZIP code?
Yes: type a five-digit ZIP code in the calculator. It finds the ZIP's center, reads the nearest National Weather Service station with a recent temperature and altimeter setting, and the USGS ground elevation there. For a spot far from the ZIP's center, tap the map or use your location instead.
Why is the number different from the airport's?
Three reasons. The station may be miles away and at another height; its reading can be up to three hours old; and airport systems may round or use other formulas. A gap of a few hundred feet is normal. For a flight from the airport itself, the airport's own report wins.
Does density altitude matter for a drone under 250 grams?
Yes, maybe more. Small drones have small propellers and little spare power, so thin air cuts their climb and flight time too, and DJI gives its smallest drones some of the lowest takeoff limits: 6,562 ft for the DJI Neo. Weight decides registration, not physics.
Is a negative density altitude possible?
Yes. On a cold day with high pressure, the air at sea level can be denser than the standard atmosphere's sea-level air; the density altitude is then below zero, such as −1,300 ft at 40 °F. Your drone gets a little extra lift, but cold batteries hold less charge.
Is this density altitude calculator free?
Yes, with no account and no app. It runs in your browser, and the live weather comes from the National Weather Service and the elevation from the U.S. Geological Survey, both public services.
Sources
Named, not linked. Read Nov 14 to 15, 2026.
The formulas
- National Weather Service, weather calculator formulas: station pressure, pressure altitude, vapor pressure, virtual temperature and density altitude; the calculator's steps are these
- FAA, Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), chapter 4 (density altitude and the humidity example), chapter 8 (the 5,048 ft example) and chapter 11 (Figures 11-2, 11-3 and 11-4); the calculator's tests check its answers against these
Drones and Part 107
- FAA, Advisory Circular 107-2A, Small Unmanned Aircraft Systems, Appendix B (performance) and Appendix E (preflight)
- FAA, Remote Pilot Small Unmanned Aircraft Systems Study Guide (FAA-G-8082-22), chapter 3b
- DJI specs pages for each model in the table, maximum takeoff altitude and flight time test conditions, read Nov 14, 2026
Live data
- National Weather Service API, api.weather.gov: the point, its observation stations and their latest observations
- U.S. Geological Survey, Elevation Point Query Service: the ground elevation
- U.S. Census Bureau 2025 Gazetteer Files and TIGERweb state boundaries: the place search and the map