Enter an altitude to get air pressure, or enter a pressure to get altitude. Results show inHg, hPa, psi and more, plus the temperature, boiling point and oxygen equivalent at that elevation, with a chart from 0 to 30,000 ft.
Enter an altitude or elevation
Height of an upper-air chart level (850, 700, 500, 300 mb)
Pick a well-known elevation
Altitude
5,280ft
1,609 m
Air pressure
24.64inHg
834.3 hPa · 12.10 psi
Pressure in every unit
inHg
24.64
hPa / mbar
834.3
psi
12.10
kPa
83.43
mmHg
625.8
atm
0.823
bar
0.8343
Standard temp (ISA)
40.2°F
4.5°C
Water boils at
202.4°F
94.7°C
% of sea level
82.3%
O₂ equivalent
17.2%
Altitude illness guide (at 5,280 ft)
Altitude illness is rare below 8,000 ft, though some people are affected at lower elevations.
Each breath holds about 82% of the oxygen it would at sea level, like breathing air that is 17.2% oxygen. This is general guidance, not medical advice.
Pressure by altitude chart
| Altitude | Meters | inHg | hPa | psi | % of sea level | Temp | Boils at | O₂ equiv. |
|---|---|---|---|---|---|---|---|---|
| 0 ft | 0 m | 29.92 | 1,013.3 | 14.70 | 100.0% | 59.0°F | 212.0°F | 20.9% |
| 1,000 ft | 305 m | 28.86 | 977.2 | 14.17 | 96.4% | 55.4°F | 210.2°F | 20.2% |
| 2,000 ft | 610 m | 27.82 | 942.1 | 13.66 | 93.0% | 51.9°F | 208.4°F | 19.5% |
| 3,000 ft | 914 m | 26.82 | 908.1 | 13.17 | 89.6% | 48.3°F | 206.5°F | 18.8% |
| 4,000 ft | 1,219 m | 25.84 | 875.1 | 12.69 | 86.4% | 44.7°F | 204.7°F | 18.1% |
| 5,000 ft | 1,524 m | 24.90 | 843.1 | 12.23 | 83.2% | 41.2°F | 202.9°F | 17.4% |
| 6,000 ft | 1,829 m | 23.98 | 812.0 | 11.78 | 80.1% | 37.6°F | 201.1°F | 16.8% |
| 7,000 ft | 2,134 m | 23.09 | 781.9 | 11.34 | 77.2% | 34.0°F | 199.3°F | 16.2% |
| 8,000 ft | 2,438 m | 22.23 | 752.6 | 10.92 | 74.3% | 30.5°F | 197.4°F | 15.6% |
| 9,000 ft | 2,743 m | 21.39 | 724.3 | 10.50 | 71.5% | 26.9°F | 195.6°F | 15.0% |
| 10,000 ft | 3,048 m | 20.58 | 696.8 | 10.11 | 68.8% | 23.3°F | 193.8°F | 14.4% |
| 11,000 ft | 3,353 m | 19.79 | 670.2 | 9.72 | 66.1% | 19.8°F | 191.9°F | 13.9% |
| 12,000 ft | 3,658 m | 19.03 | 644.4 | 9.35 | 63.6% | 16.2°F | 190.1°F | 13.3% |
| 13,000 ft | 3,962 m | 18.29 | 619.4 | 8.98 | 61.1% | 12.6°F | 188.3°F | 12.8% |
| 14,000 ft | 4,267 m | 17.58 | 595.2 | 8.63 | 58.7% | 9.1°F | 186.4°F | 12.3% |
| 15,000 ft | 4,572 m | 16.89 | 571.8 | 8.29 | 56.4% | 5.5°F | 184.6°F | 11.8% |
| 16,000 ft | 4,877 m | 16.22 | 549.2 | 7.96 | 54.2% | 1.9°F | 182.7°F | 11.4% |
| 17,000 ft | 5,182 m | 15.57 | 527.2 | 7.65 | 52.0% | -1.6°F | 180.9°F | 10.9% |
| 18,000 ft | 5,486 m | 14.94 | 506.0 | 7.34 | 49.9% | -5.2°F | 179.0°F | 10.5% |
| 19,000 ft | 5,791 m | 14.34 | 485.5 | 7.04 | 47.9% | -8.8°F | 177.2°F | 10.0% |
| 20,000 ft | 6,096 m | 13.75 | 465.6 | 6.75 | 46.0% | -12.3°F | 175.3°F | 9.6% |
| 21,000 ft | 6,401 m | 13.18 | 446.5 | 6.48 | 44.1% | -15.9°F | 173.5°F | 9.2% |
| 22,000 ft | 6,706 m | 12.64 | 427.9 | 6.21 | 42.2% | -19.5°F | 171.6°F | 8.8% |
| 23,000 ft | 7,010 m | 12.11 | 410.0 | 5.95 | 40.5% | -23.0°F | 169.8°F | 8.5% |
| 24,000 ft | 7,315 m | 11.60 | 392.7 | 5.70 | 38.8% | -26.6°F | 167.9°F | 8.1% |
| 25,000 ft | 7,620 m | 11.10 | 376.0 | 5.45 | 37.1% | -30.2°F | 166.0°F | 7.8% |
| 26,000 ft | 7,925 m | 10.63 | 359.9 | 5.22 | 35.5% | -33.7°F | 164.2°F | 7.4% |
| 27,000 ft | 8,230 m | 10.17 | 344.3 | 4.99 | 34.0% | -37.3°F | 162.3°F | 7.1% |
| 28,000 ft | 8,534 m | 9.73 | 329.3 | 4.78 | 32.5% | -40.9°F | 160.4°F | 6.8% |
| 29,000 ft | 8,839 m | 9.30 | 314.9 | 4.57 | 31.1% | -44.4°F | 158.5°F | 6.5% |
| 30,000 ft | 9,144 m | 8.89 | 300.9 | 4.36 | 29.7% | -48.0°F | 156.6°F | 6.2% |
Theoretical values from the International Standard Atmosphere (ISA: 29.92 inHg and 59°F at sea level). The row closest to your result is highlighted in blue.
TIPS
At this altitude, a 1 inHg change in pressure moves an altimeter reading by about 1,082 ft (1 hPa is about 32.0 ft). Recalibrate a hiking altimeter whenever you pass a point with a known elevation.
Cooking: Pasta, rice and beans take noticeably longer to cook at this elevation.
Sea-level pressure changes with the weather. For real-world use, enter the current altimeter setting (QNH) and temperature under "Use today's conditions".
How air pressure changes with altitude, and how to calculate it
The higher you go, the less air sits above you, so the pressure drops. Near sea level, pressure falls about 1 inHg for every 925 ft of climb. The International Standard Atmosphere (ISA) turns this into a formula that meteorologists, pilots and hikers all use.
This calculator uses that formula to convert in both directions. Type an altitude in feet or meters to get the pressure, or type a pressure to get the altitude. It shows inHg, hPa, psi, kPa, mmHg, atm and bar side by side, along with a chart from 0 to 30,000 ft. For each result you also get the temperature, the boiling point of water, the share of sea-level pressure and an oxygen equivalent.
To match real conditions, enter today's altimeter setting (QNH) and temperature. The calculation then works the way a barometric altimeter does, which helps when you check or calibrate a hiking altimeter or watch.
You can also switch the temperature basis to your local temperature to find altitude from a pressure you measured on the spot, or tap 850, 700, 500 or 300 mb to see how high those weather-chart levels sit.
Common uses: hiking, flying, weather and cooking
Planning a hike or mountain trip
Enter the summit elevation to see the pressure, standard temperature and boiling point you can expect, along with the altitude illness guide.
Calibrating a barometric altimeter or watch
Set the sea-level pressure to today's altimeter setting, or adjust it until the reading matches a spot with a known elevation.
Looking up pressure at a given elevation
Generate a chart in 1,000, 2,000 or 5,000 ft steps and copy it as tab-separated text to paste into a spreadsheet.
Reading upper-air weather charts
Use the 850, 700, 500 and 300 mb buttons to see the altitude, standard temperature and boiling point of each level.
Turning a pressure sensor reading into height
Enter the pressure from a barometer, data logger or microcontroller sensor, and add your local temperature for a closer estimate of altitude.
Finding pressure altitude
Keep the sea-level setting at 29.92 inHg and enter the pressure at your location to get pressure altitude.
Adjusting cooking for high elevation
Check how far the boiling point falls at your elevation before cooking rice, pasta or beans on a mountain trip or in a high-altitude home.
Science class and curiosity
Compare pressure, temperature, boiling point and oxygen at real places such as Denver, Pikes Peak and Mount Everest.
Steps: convert feet to inHg, or inHg back to feet
- Choose "Altitude → Pressure" or "Pressure → Altitude."
- Enter an altitude in feet or meters, or a pressure in inHg, hPa, psi or another unit. The slider and the preset buttons work too.
- Read the other value, plus the temperature, boiling point, percentage of sea-level pressure and oxygen equivalent.
- To match real weather, open "Use today's conditions" and enter the current altimeter setting (QNH) and temperature.
- Check the chart below the results, and press "Copy table" to paste it into a spreadsheet.
Note: All calculations run in your browser. Nothing you enter is sent to a server.
Accuracy, ranges and model limits
- By default the results are theoretical values for the International Standard Atmosphere (29.92 inHg and 59°F at sea level). Real pressure changes with the weather, so measured readings will differ.
- Sea-level pressure can be set from 25.69 to 32.04 inHg (870 to 1,085 hPa). Sea-level temperature can be set from -22°F to 122°F, and local temperature from -76°F to 122°F. Values outside these ranges are limited automatically.
- The supported altitude range is -1,640 ft to 65,617 ft (-500 m to 20,000 m). Up to 36,089 ft (11,000 m) the calculation uses the troposphere formula. Above that it uses the lower stratosphere formula.
- The boiling point is an approximation from the Antoine equation for water. The altitude illness guide and oxygen equivalent show general trends only, and people react differently. Ask a doctor about your own health at altitude.
- Privacy: this tool runs entirely in your browser, and the numbers you enter never leave your device.
Barometric pressure by elevation: Denver, Pikes Peak, Everest and more
Standard-atmosphere (ISA) values for well-known elevations. The temperature column is the standard temperature for that altitude, not a measured one. The jet cruise row uses 35,000 ft as a typical example.
| Location | Elevation | inHg | hPa | % of sea level | Temp | Water boils at | O₂ equiv. |
|---|---|---|---|---|---|---|---|
| Jet cruise altitude | 35,000 ft (10,668 m) | 7.04 | 238.4 | 23.5% | -65.8°F | 147.2°F | 4.9% |
| Mount Everest summit | 29,032 ft (8,849 m) | 9.28 | 314.4 | 31.0% | -44.5°F | 158.5°F | 6.5% |
| Denali summit | 20,310 ft (6,190 m) | 13.57 | 459.6 | 45.4% | -13.4°F | 174.8°F | 9.5% |
| Kilimanjaro summit | 19,341 ft (5,895 m) | 14.13 | 478.6 | 47.2% | -10.0°F | 176.6°F | 9.9% |
| Mt. Whitney summit | 14,505 ft (4,421 m) | 17.23 | 583.3 | 57.6% | 7.3°F | 185.5°F | 12.1% |
| Pikes Peak summit | 14,115 ft (4,302 m) | 17.50 | 592.5 | 58.5% | 8.7°F | 186.2°F | 12.3% |
| Airliner cabin limit (FAA) | 8,000 ft (2,438 m) | 22.23 | 752.6 | 74.3% | 30.5°F | 197.4°F | 15.6% |
| Denver | 5,280 ft (1,609 m) | 24.64 | 834.3 | 82.3% | 40.2°F | 202.4°F | 17.2% |
| Sea level | 0 ft (0 m) | 29.92 | 1,013.3 | 100.0% | 59.0°F | 212.0°F | 20.9% |
| Badwater Basin, Death Valley | -282 ft (-86 m) | 30.23 | 1,023.6 | 101.0% | 60.0°F | 212.5°F | 21.2% |
How pressure falls with each 1,000 ft
Starting from 29.92 inHg at sea level, the standard atmosphere gives 28.86 inHg at 1,000 ft, 27.82 inHg at 2,000 ft, 26.82 inHg at 3,000 ft, 24.90 inHg at 5,000 ft, 20.58 inHg at 10,000 ft, 13.75 inHg at 20,000 ft and 8.89 inHg at 30,000 ft. The drop per foot gets smaller as you climb. Near sea level it takes about 925 ft to lose 1 inHg, while near 14,000 ft it takes about 1,420 ft. This is why barometric altimeter errors grow with height.
If the chart doesn't match your reading
The chart assumes 29.92 inHg and 59°F at sea level. On a real day, sea-level pressure may be higher or lower, and the difference carries through to every elevation. To match today's weather, enter the current altimeter setting under "Use today's conditions." The whole chart is recalculated.
Background: why pressure falls, what altimeters measure and why water boils cooler
How the calculation works, and how to read the numbers when you hike, fly or cook at elevation.
Pressure is the weight of the air above you
Air pressure at any point is the weight of the column of air above it. The higher you go, the less air sits overhead, so pressure falls. The air itself also thins with height, so the drop is exponential, not a straight line. Near sea level, 1 hPa matches about 27 ft of altitude. Near 14,000 ft, the same 1 hPa matches about 42 ft.
Altimeter setting (QNH) and why you update it
A barometric altimeter measures pressure and converts it to height using a sea-level reference called the altimeter setting, or QNH. Pilots set the value reported by a nearby airport. Because weather changes the real pressure, an old setting shifts the reading. Near sea level, an error of 1 inHg shifts the reading by about 925 ft. For hiking, recalibrate at any spot with a known elevation.
Troposphere and lower stratosphere: why the formula changes at 36,089 ft
In the troposphere (up to 36,089 ft or 11,000 m) the standard atmosphere cools by about 3.6°F per 1,000 ft. In the lower stratosphere (36,089 ft to 65,617 ft) the standard temperature stays near -69.7°F, so the pressure formula changes form. The calculator switches between the two automatically, which lets it handle jet cruise altitudes.
Why water boils at a lower temperature at altitude
Water boils when its vapor pressure matches the surrounding air pressure. With less air pressure, that happens at a lower temperature, about 1.8°F lower for every 1,000 ft in the lower few thousand feet. In the standard atmosphere that is 202.4°F in Denver and 185.5°F on Mt. Whitney. Pasta, rice and beans take longer to soften as the boiling point drops, and a pressure cooker restores a higher cooking temperature.
The oxygen percentage doesn't change; the pressure does
Oxygen makes up about 20.95% of the air at every altitude. What changes is the pressure, so each breath carries fewer oxygen molecules. At 14,505 ft on Mt. Whitney the pressure is 57.6% of sea level, which is like breathing 12.1% oxygen at sea level. The CDC notes that unacclimatized travelers going above 8,000 ft are at risk for altitude illness, so ascend gradually.
Why airliner cabins are held near 8,000 ft
Jets cruise where outside pressure is only about 7 inHg, but US rules for transport category airplanes (14 CFR 25.841) require the cabin pressure altitude to stay at or below 8,000 ft in normal operation. That equals 22.23 inHg. A higher cabin pressure would mean a larger pressure difference across the fuselage. This is also why sealed snack bags puff up and ears pop in flight.
Common mistakes when reading pressure and elevation
Using an old altimeter setting
A barometric altimeter reads height from a sea-level reference. If you leave last week's setting in place, the weather difference becomes a height error. Near sea level, each 0.1 inHg of error moves the reading by about 90 ft.
💡 See the solution▼
Mixing up pressure units
inHg, hPa, psi and mmHg differ by large factors. One standard atmosphere is 29.92 inHg, 1013.25 hPa, 14.70 psi or 760 mmHg. Reading a value in the wrong unit makes the pressure look wildly high or low.
💡 See the solution▼
Comparing sea-level pressure with a raw sensor reading
Weather reports are usually adjusted to sea level, but a barometer or phone sensor shows the actual pressure where you stand. The two numbers disagree by a lot at elevation, which looks like an error but isn't.
💡 See the solution▼
Forgetting the lower boiling point when cooking
At a mountain cabin or campsite, rice and pasta are often undercooked because water boils well below 212°F. At 8,000 ft it boils at about 197°F.
💡 See the solution▼
Gaining elevation too fast on the first day
Going straight from low ground to a high-elevation lodge can bring on altitude illness, especially above 8,000 ft.
💡 See the solution▼
Air pressure and elevation: frequently asked questions
Q.How much does air pressure drop as altitude increases?
A. Near sea level, pressure falls about 1 inHg for every 925 ft you climb (roughly 1 hPa per 27 ft). In the standard atmosphere that works out to 28.86 inHg at 1,000 ft, 24.90 inHg at 5,000 ft, 20.58 inHg at 10,000 ft and 17.58 inHg at 14,000 ft. The drop slows as the air thins, so near 14,000 ft it takes about 1,420 ft of climbing to lose 1 inHg.
Q.What is the air pressure in Denver?
A. At Denver's official elevation of 5,280 ft, the standard atmosphere gives 24.64 inHg (834.3 hPa, 12.10 psi), which is 82.3% of sea-level pressure. A barometer reads this value only on an average day. Weather moves the real number up or down. Enter today's altimeter setting under "Use today's conditions" to get a closer match.
Q.Is there a printable air pressure by altitude chart?
A. Yes. The chart under the calculator covers 0 to 30,000 ft in steps of 1,000, 2,000 or 5,000 ft. Each row lists pressure in inHg, hPa and psi, the percentage of sea-level pressure, temperature, the boiling point of water and the oxygen equivalent. Press "Copy table" to copy it as tab-separated text, then paste it into Excel or Google Sheets to print or edit it.
Q.How do I calculate altitude from air pressure?
A. Switch to "Pressure → Altitude," pick a unit (inHg, hPa, psi, kPa, mmHg, atm or bar) and enter the pressure. The calculator solves the standard-atmosphere formula for altitude. If you also know the temperature where you are, open "Use today's conditions," choose "Local (at your location)" and enter it. The tool then uses h = (T + 273.15) / 0.0065 × ((sea-level pressure / pressure)^(1/5.256) − 1), with T in °C. For example, with 29.92 inHg at sea level, a reading of 25.10 inHg (850 hPa) at 50°F gives about 4,858 ft, compared with 4,781 ft in the standard atmosphere.
Q.How do I find pressure altitude?
A. Pressure altitude is the altitude at which the standard atmosphere has the pressure you measure. Switch to "Pressure → Altitude," keep the sea-level setting at the default 29.92 inHg and enter the actual pressure at your location. The result is the pressure altitude. Use the pressure at your location (station pressure), not an altimeter setting. This tool does not calculate density altitude.
Q.What should I set my altimeter or hiking watch to?
A. A barometric altimeter converts pressure to height using a sea-level reference called the altimeter setting (QNH). Pilots use the setting reported by a nearby airport. For hiking, the easiest method is to calibrate at a spot with a known elevation, such as a trailhead sign. In the calculator, use "Pressure → Altitude," enter your measured pressure, then adjust the sea-level pressure under "Use today's conditions" until the altitude matches the known elevation. That value is your setting for the day.
Q.Is the pressure in my weather app the same as what my barometer reads?
A. Usually not. Weather reports normally give pressure adjusted to sea level, while a barometer or phone sensor reads the actual pressure where you are. At 5,000 ft the actual reading is about 5 inHg lower than the sea-level figure in the same report. To convert a raw reading to altitude, enter it in "Pressure → Altitude." To use a sea-level figure from a forecast, enter it as the sea-level pressure under "Use today's conditions."
Q.How high are the 850, 700, 500 and 300 mb levels on weather charts?
A. In the standard atmosphere, 850 mb is about 4,781 ft (1,457 m), 700 mb is about 9,883 ft (3,012 m), 500 mb is about 18,289 ft (5,575 m) and 300 mb is about 30,066 ft (9,164 m). Real heights vary with temperature and the weather pattern. The 850, 700, 500 and 300 buttons in the calculator show each level's altitude, temperature and boiling point. One millibar (mb) equals one hectopascal (hPa).
Q.Which pressure units does the calculator support?
A. It supports inHg, hPa (the same as millibars), psi, kPa, mmHg, atm and bar, and shows all seven at once. Standard sea-level pressure is 29.92 inHg, which equals 1013.25 hPa, 14.70 psi, 760 mmHg and 1 atm. In the standard atmosphere, 1 inHg is 33.8639 hPa. Weather reports in the US use inHg for altimeter settings, while most other countries use hPa.
Q.What do the temperature, boiling point and oxygen equivalent mean?
A. Temperature is the standard-atmosphere value for that altitude, which drops about 3.6°F per 1,000 ft in the lower atmosphere. It is not a forecast. The boiling point is the temperature at which water boils at that pressure, about 202°F in Denver and 185°F on Mt. Whitney. The oxygen equivalent restates the lower pressure as the oxygen concentration you would breathe at sea level. Oxygen stays at about 20.95% of the air at any altitude, but at 14,505 ft each breath carries the oxygen of 12.1% air at sea level.
Q.What is the air pressure inside an airplane cabin?
A. FAA rules for transport category airplanes require a cabin pressure altitude of no more than 8,000 ft under normal operating conditions. In the standard atmosphere that is 22.23 inHg (752.6 hPa). Outside at a typical 35,000 ft cruise the pressure is only 7.04 inHg (238.4 hPa). Use the cabin and cruise buttons in the calculator to see the full numbers.
Q.How accurate is the calculation?
A. By default the results are theoretical values for the International Standard Atmosphere (ISA), which assumes 29.92 inHg and 59°F at sea level. Real pressure changes with the weather, so a measured reading can differ from the standard value at the same elevation. Enter the current sea-level pressure and temperature under "Use today's conditions" to bring the calculation closer to real conditions. Boiling points come from an Antoine-equation approximation for water.
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