Specific surface area converter
Convert specific surface area between m²/g and the other units, and see roughly what particle size it implies.
That's 4× as fine as a catalyst support, while activated carbon is 1.2× higher. A five-gram spoonful would cover about 19.16 tennis courts.
What it means
How much surface is that?
Particle sizes assume smooth spheres at 2.5 g/cm³. Real porous materials have far more area than their outside size suggests, which is the point of measuring.
Every unit
Your area in every unit
Learn
Three things worth knowing
-
Area = 6 ÷ (density × diameter)
For smooth spheres. A material with far more area than that formula predicts is porous, and the pores are where the chemistry happens.
-
Measured by freezing gas onto it
The BET method cools a sample and measures how much nitrogen sticks to it. Counting the molecules in one layer gives the area, pores and all.
-
Area is not porosity
A material can have huge pores and little area, or tiny ones and enormous area. Area counts the walls; porosity counts the space between them.
Shortcuts
Popular surface area conversions
Background
About specific surface area
Break a solid into smaller pieces and the surface grows while the mass stays the same. Specific surface area counts that surface per gram, and it decides how fast anything reacts, adsorbs or dissolves.
Sand is a hundredth of a square meter per gram. Activated carbon is over a thousand — a spoonful has the area of several tennis courts.