Magnitude Brightness Ratio Calculator
Compare the received brightness of two sources measured in the same photometric band.
Calculate locally
No account, API or uploaded inputs. All calculations run in this browser.
Worked example
Magnitude 0 compared with magnitude 5 gives F1/F2 = 100. Reversing the inputs gives 0.01. Equal magnitudes give 1, even when both magnitudes are negative.
Method and units
The magnitude definition gives F1/F2 = 10^[0.4 × (m2 − m1)]. The ratio is dimensionless. A smaller magnitude denotes a brighter source; negative magnitudes are valid.
What this result means
Use the same band and photometric zero-point system. Apparent magnitudes compare received flux, not intrinsic luminosity; distance and extinction can differ. Colours or a band mismatch can invalidate the comparison. No uncertainties or extinction corrections are computed.