Kepler's Third Law Calculator

T²=a³, planet table

Quick Answer

Kepler's Third Law Calculator: T²=a³, planet table. Kepler's Third Law Calculator uses standard science & engineering formulas to compute accurate results instantly.

Semi-major axis (AU)

Orbital period at 1.524 AU

1.881 years

T² = a³

Period (years)1.8814

Period (days)687.2

Semi-major axis1.5240 AU

Distance (million km)228.0

Calculation steps

1Cube the semi-major axis: a³ = 1.5240³ = 3.5396
2Take the square root: T = √(a³) = √3.5396 = 1.8814 years

T² = a³ with T in years and a in AU only holds for orbits around the Sun (T²/a³ = 1 is really a statement about solar mass). For satellites around Earth or other bodies, use the full form T² = 4π²a³/(GM). The Moon preset above is illustrative only.

Solar system planets

Planet	a (AU)	T (years)	T²/a³
Mercury	0.387	0.241	1.0021
Venus	0.723	0.615	1.0008
Earth	1	1	1.0000
Mars	1.524	1.881	0.9996
Jupiter	5.203	11.86	0.9986
Saturn	9.537	29.45	0.9999
Uranus	19.19	84.02	0.9989
Neptune	30.07	164.8	0.9989

Kepler's third law: T²/a³ ≈ 1 when T is in years and a in AU (orbiting the Sun). 1 AU = 149.6 million km.

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How to Use

Enter known quantities: fill values and confirm units in the Kepler's Third Law Calculator.
Instant solution: unknowns solve live with the formula shown transparently.
Use constant/material tables: standard physical constants and material data are listed on this page.
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Key Points

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Key capability: T²=a³, planet table.
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Formula & How It Works

Kepler's Third Law Calculator formula

Kepler's Third Law Calculator uses standard science & engineering formulas to compute accurate results instantly.

FAQ

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Source & Updates

Based on CODATA recommended constants and standard physics formulas. Last updated: 2025-07

Last updated: 2026-08-06

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Cite this page: YiJianSuan. Kepler's Third Law Calculator[EB/OL]. https://www.yijiansuan.com/en/c/science/kepler

Results provided by this tool are for reference only and do not constitute professional advice.