Standard acceleration of gravity

$g_{n}$ = 9.806 65 m s⁻²

Value: 9.806 65 m s⁻²
Standard uncertainty: exact
Relative uncertainty: exact
Status: Exact: conventional value adopted in 1901
Symbol: $g_{n}$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# standard acceleration of gravity, CODATA 2022 (NIST)
g_n = 9.80665  # m s^-2, exact

# SciPy: scipy.constants.physical_constants['standard acceleration of gravity']

What it is

A conventional value adopted by the 3rd General Conference on Weights and Measures in 1901, not a measurement: real gravity varies from about 9.78 m/s² at the equator to 9.83 m/s² at the poles. It defines units such as the kilogram-force and the g used for accelerations.

Equations

$1 kgf = gₙ×1 kg$ kilogram-force

In other units

Unit	Value
CGS (cm s⁻²)	980.665	exact

Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display.

Standard gravity in ft/s², m/s² and other units →

How the value changed, 1998–2022

CODATA	Value (uncertainty)	Relative uncertainty	Change from previous
2022	9.806 65	exact	exact
2018	9.806 65	exact	exact
2014	9.806 65	exact	exact
2010	9.806 65	exact	exact
2006	9.806 65	exact	exact
2002	9.806 65	exact	exact
1998	9.806 65	exact

“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).

Related constants

Adopted exact

atm

Standard atmosphere 101 325 Pa Universal

G

Gravitational constant 6.674 30(15) × 10⁻¹¹ m³ kg⁻¹ s⁻²