Free · Physics models
Stellar Parallax Distance
Convert positive angular parallax into distance in parsecs, with optional illustrative star presets.
- Formula & worked example
- Private in your browser
- No signup
Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
A 100 milliarcsecond parallax is 0.1 arcsecond and corresponds to 10 parsecs.
d in pc = 1/(p in arcseconds).
Worked example
Enter these known values and leave the other values blank.
- Star
- Custom star
- Parallax custom
- 100 marcsec
- Distance custom
- 10 pcs
Assumptions and limitations
- The reciprocal relation uses annual stellar parallax. Inputs must be positive; zero parallax does not imply a finite distance.
- Star presets are captured illustrative values rather than a current astrometric catalog. Uncertainty and parallax bias are not modeled.
- Enter known quantities and clear the unknown to use available inverse branches. Locks retain supplied values. Consistency messages cover fully visible equations; identities with hidden dependencies may require a manual consistency check. Preset values are illustrative approximations, and unit selectors preserve the underlying quantity.
Common questions
How do I solve for a different quantity?
Clear that quantity and supply enough independent known values. Some outputs are one-way or tied to a selected preset, so they cannot determine every input.
References
The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.