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Choose a barometer with a MEMS pressure sensor stating ±1 hPa accuracy and 0.1 hPa resolution, a display or app that shows both absolute (station) pressure and sea-level pressure once you enter your altitude, and a trend or logging function so you can see changes over hours. Decide the form: a standalone digital barometer or weather station for weather and home records; a pressure channel inside an air quality monitor for sensor compensation; a bare sensor module for a custom logger. Check it once against a nearby airport or weather service reading.
Why measure pressure
- Weather: a falling trend of more than about 3 hPa in three hours signals approaching wind and rain; a steady rise, settled weather.
- Gas sensor compensation: NDIR CO₂ readings and electrochemical oxygen readings shift with pressure; monitors with a barometer correct for it. See CO₂ monitor accuracy explained.
- Radon: falling pressure draws radon from the soil; pressure logs explain radon swings. See what radon is.
- Altitude: pressure gives altitude to a few meters once referenced.
- Building pressure: differential pressure between inside and out (a different instrument, a manometer) shows whether a house is depressurized by extract fans, which affects combustion appliances and radon entry.
Specifications
| Spec | Look for |
|---|---|
| Accuracy | ±1 hPa; ±0.5 for research |
| Resolution | 0.1 hPa |
| Range | 300 to 1,100 hPa covers sea level to high mountains |
| Units | hPa, mbar, mmHg, inHg switchable |
| Sea-level correction | Altitude entry or reference-pressure entry |
| Trend | 3-hour and 12-hour change; graph |
| Logging | Hourly readings for weeks; export |
| Temperature compensation | Stated; MEMS sensors drift with temperature |
Forms
- Weather stations (Netatmo, Newentor, Ecowitt and similar) include a barometer with trend, history and often an app. The easiest route for weather and home records.
- Air quality monitors with pressure (Aranet4, Airthings View Plus, GoveeLife H5140) use it for compensation and expose it in the app.
- Standalone digital barometers for a desk or a boat; check they state accuracy.
- Sensor modules (Bosch BMP280/BME280/BMP390, TE MS5611) for DIY loggers, with ±1 hPa or better and excellent resolution.
- Aneroid dial barometers: decorative and drifting; adjust against a reference and treat as a trend indicator.
Absolute versus sea-level
Pressure falls about 12 hPa per 100 m of altitude. A sensor at 300 m reads about 977 hPa on a day the forecast says 1,013. Enter the altitude (or the current sea-level pressure from a nearby station) and the meter displays sea-level pressure for comparison. Keep absolute pressure for sensor compensation and altitude calculation.
Checking it
Compare the sea-level reading with a nearby airport METAR or weather service at the same time; agreement within 1 to 2 hPa is fine. Most digital barometers allow an offset. Aneroid dials have an adjusting screw on the back.
Barometers and weather stations sit in the environmental monitoring category; for logging setups, see how to set up long-term environmental data logging.
Recommended Tools
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Frequently Asked Questions
What accuracy should a barometer have?
±1 hPa (about 1 mbar or 0.03 inHg) is good for weather and compensation uses; ±0.5 hPa for research. Resolution of 0.1 hPa lets you see trends over hours.
What is the difference between absolute and sea-level pressure?
Absolute (station) pressure is what the sensor actually measures at your altitude. Sea-level pressure adds a correction for altitude so readings can be compared with forecasts and other sites. Set the meter's altitude or a known reference to get sea-level.
Why do CO₂ monitors care about pressure?
NDIR sensors count molecules in the light path; fewer molecules at lower pressure mean a lower reading for the same ppm. A pressure sensor lets the monitor compensate, which matters at altitude.
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