✨ Stellar Parallax Distance Calculator
Convert a star's parallax angle to its distance — in parsecs and light-years — or work out the parallax for a given distance.
Distance
10 pc
Light-years
32.62
Parsecs
10
As Earth orbits the Sun, nearby stars appear to shift against distant ones. Half that shift is the parallax angle, and distance (parsecs) = 1 ÷ parallax (arcseconds) — that\'s the very definition of a parsec. 1 parsec ≈ 3.26 light-years. Proxima Centauri\'s parallax of 0.77″ puts it 1.30 pc (4.24 ly) away. 🔒 In your browser.
How the stellar parallax distance calculator works
As Earth orbits the Sun, nearby stars appear to shift slightly against the far background; half that annual shift is the star's parallax angle. The distance follows directly: distance in parsecs = 1 ÷ parallax in arcseconds — which is exactly how the parsec ("parallax-arcsecond") is defined. The tool converts either way and also gives light-years (1 parsec ≈ 3.26 ly).
Parallax is the first rung of the cosmic distance ladder and the only direct way to measure stellar distances. The angles are tiny — even the nearest star shifts under one arcsecond — which is why space telescopes like Gaia are needed to measure them precisely.
Frequently asked questions
How do you calculate distance from parallax?
Distance in parsecs = 1 ÷ parallax angle in arcseconds. A star with a parallax of 0.1 arcseconds is 10 parsecs (about 32.6 light-years) away. It's the definition of the parsec.
What is stellar parallax?
The apparent shift of a nearby star against distant background stars as Earth moves around the Sun. The bigger the shift, the closer the star — it's the most direct way to measure stellar distances.
What is a parsec?
The distance at which a star shows a parallax of one arcsecond — about 3.26 light-years or 3.09×10¹³ km. The name is short for "parallax of one arcsecond."
How far away is Proxima Centauri by parallax?
Its parallax is about 0.77 arcseconds, giving a distance of 1 ÷ 0.77 ≈ 1.30 parsecs, or about 4.24 light-years — the nearest star to the Sun.
Why are parallax angles so small?
Because stars are enormously far away compared with the size of Earth's orbit. Even the nearest shifts by under one arcsecond — a coin seen from several kilometres away — which is why precise measurement needs space telescopes.