National Physical Laboratory

Online Barograph

There is no need to tap the screen...

The NPL online barograph has been recording the pressure in Teddington, UK, since 1 January 1998.

The barometric pressure data is derived from an on-line electronic pressure transducer. The measurement uncertainty of this on-line transducer is approximately ±0.3 hPa. The unit hectopascal (hPa) is numerically identical to the millibar (mbar) - see Pressure Units

The pressure values shown are those at the point of measurement, that is approximately 10 metres above mean sea level. If a hole were dug to sea level, the pressure at the bottom would be about 1 hPa greater than at the top. Note that, when estimating a pressure value from the graphs, the uncertainty will be considerably higher than that of the measuring transducer because of limitations in screen resolution.

When using the pressure values, particularly for checking another barometer, it is important to appreciate that the differences in altitude, distance from Teddington and weather conditions may seriously limit the validity of the comparison.

View the NPL Online Barograph

A list of frequently asked questions relating to the online barograph and barometers is given below.

Barograph FAQs

Barometer FAQs


Please note that the information will not be divulged to third parties, or used without your permission