When to use this calculator
Compare received flux from a difference in astronomical magnitudes. Magnitudes must use compatible passbands and zero-point conventions.
Explore the astronomical distance calculators for other questions in this topic. For a related calculation, use the Observed Wavelength From Redshift Calculator: Find observed wavelength for a stated rest wavelength and redshift.
PUTTING IT INTO PRACTICE
Magnitude Flux Ratio: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| First apparent magnitude | 1 |
| Second apparent magnitude | 6 |
| Result | 100 × |
- Check the input labels and enter the example values above.
- Apply the relationship: First/second flux = 10^(0.4 × (second magnitude−first magnitude)).
- The result is 100 ×, rounded for display.
How to interpret your result
Magnitudes must use compatible passbands and zero-point conventions.
A light-time calculation uses vacuum propagation speed. Parallax angle must use the stated angular unit. Simple inverse-parallax estimates can be unreliable when measurement uncertainty is large relative to the parallax.
Frequently asked questions
Are a parsec and a light-year the same unit?
No. Both measure astronomical distance but use different definitions. A parsec is defined through the parallax relationship.
When is the magnitude flux ratio calculator useful?
Compare received flux from a difference in astronomical magnitudes. Magnitudes must use compatible passbands and zero-point conventions.
How do I use the magnitude flux ratio calculator?
Enter first apparent magnitude, second apparent magnitude. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
First/second flux = 10^(0.4 × (second magnitude−first magnitude)).
What should I check before using the result?
Magnitudes must use compatible passbands and zero-point conventions.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see OpenStax: stellar distances and parallax ↗. This is a topic reference, not an external review or endorsement of this tool.
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