A few tables to give some idea of scale and conversions between humidity values in different units.

 

Air temperature, dew point, and relative humidity

Approximate values of relative humidity are shown for a selection of dew points and air temperatures.

 

Values of relative humidity in air at selected temperatures and dew points

Air temperature /°C	0	5	10	15	20	25	30	35	40	50
Dew-point temperature /°C	Relative humidity /%rh
0	100	70	50	36	26	19	14	11	8	5
5	-	100	71	51	37	28	21	16	12	7
10	-	-	100	72	53	39	29	23	17	10
15	-	-	-	100	73	54	40	30	23	14
20	-	-	-	-	100	74	55	42	32	19
25	-	-	-	-	-	100	75	56	43	26
30	-	-	-	-	-	-	100	75	58	34
35	-	-	-	-	-	-	-	100	76	46
40	-	-	-	-	-	-	-	-	100	60
50	-	-	-	-	-	-	-	-	-	100

Vapour concentration (also known as volumetric humidity or absolute humidity)

The table shows the approximate mass of water (in grams) contained in a cubic metre (m³) of saturated air at a total pressure of 101 325 Pa (1013.25 mbar). Unsaturated air will contain comparatively less.

Mass of water vapour per cubic metre of saturated air

Temperature /ºC	0	5	10	15	20	25	30	35
Water vapour / (g/m3)	4.9	6.8	9.4	12.9	17.4	23.1	30.5	39.8

For air at atmospheric pressure, a few comparative values are shown of dew point (frost point), saturation vapour pressue, and amount fraction.

Comparison of humidity values

Dew-point temperature (frost point below 0 °C) °C	Saturation vapour pressure Pa	Amount fraction (fraction of vapour in total amount of air)
		Percent (%)	Parts in 106*
100	101419	100
80	47695	47
60	20065	20
40	7421	7.3
20	2349	2.3
10	1233	1.2
0	614	0.6
-10	261	0.3
-20	103	0.1	1024
-40	12.9		127
-60	1.1		11
-80	0.06		0.5

*(informally known as 'parts per million')

9 of 11

Good practice online modules

← Return to the main menu

• Humidity measurement
• Humidity basics
• Hygrometers
• Measuring humidity