What is standard gravity (g)?
Standard acceleration of gravity is g_n = 9.80665 m/s^2 exactly (defined value, zero uncertainty). It is the conventional value for Earth's surface gravity.
Open the interactive PhysRef tool →Key facts
| Value | 9.80665 m/s^2 |
|---|---|
| Symbol | g_n |
| Exactness | Exact by definition (uncertainty 0) |
| Defined by | CGPM 1901 / BIPM SI Brochure |
| Use | Weight, kgf, standard conditions |
Frequently asked questions
What is the value of standard gravity?
g_n = 9.80665 m/s^2, the conventional standard value of gravitational acceleration on Earth.
Is g exactly 9.81?
The standard defined value is exactly 9.80665 m/s^2; 9.81 is a common rounding. Actual local gravity varies from about 9.78 to 9.83 m/s^2.
Why is standard gravity defined?
It fixes the relation between mass and weight, e.g. the kilogram-force equals 1 kg times 9.80665 m/s^2.
Related pages
Standard gravity is part of PhysRef on GOAT Lab — a free reference you can use without signing up, and it works offline. Open the tool above for any custom value.
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