thumb|250px|A laboratory ultracentrifuge.
In chemistry, a Svedberg unit or svedberg (symbol S, sometimes Sv) is a non-SI metric unit for sedimentation coefficients. The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration (i.e. how fast a particle of given size and shape settles out of suspension). in chemistry for his work on disperse systems, colloids and his invention of the ultracentrifuge.
Factors
The Svedberg coefficient is a nonlinear function.
The sedimentation coefficient is the ratio of the speed of a substance in a centrifuge to its acceleration in comparable units. A substance with a sedimentation coefficient of 26S () will travel at 26 micrometers per second () under the influence of an acceleration of 1 million gravities (10<sup>7</sup> m/s<sup>2</sup>). Centrifugal acceleration is given as rω; where r is the radial distance from the rotation axis and ω is the angular velocity in radians per second.
Bigger particles tend to sediment faster and so have higher Svedberg values.
Svedberg units are not directly additive since they represent a rate of sedimentation, not weight.