OrbitLab

Apparent Magnitude Calculator

Brightness as seen from here.

Absolute magnitude (M)

Distance (parsecs)

Apparent magnitude

4.83

What you entered

Absolute magnitude (M): 4.83Distance (parsecs): 10

1
5 × (log₁₀(d) − 1)
5 × (log₁₀(10) − 1)= 0
2
m = M + 5(log₁₀(d) − 1)
4.83 + 0= 4.83

Result

Apparent magnitude: 4.83

From 10 parsecs away, this object would appear at magnitude 4.83 — lower numbers are brighter.

Apparent magnitude from absolute magnitude and distance

The distance modulus: apparent magnitude equals absolute magnitude plus 5 times the log of distance in parsecs, minus 5. Larger magnitudes mean fainter objects.

Absolute magnitude	Distance	Apparent magnitude	Visibility
4.83 (Sun-like)	1 pc	-0.170	Among the brightest stars
4.83 (Sun-like)	10 pc	4.830	Just visible in dark skies
4.83 (Sun-like)	100 pc	9.830	Binoculars needed
4.83 (Sun-like)	1,000 pc	14.830	Telescope needed
-5 (supergiant)	100 pc	0.000	One of the brightest in the sky
1.4 (Sirius)	2.64 pc	-1.492	The brightest night-sky star

Each 5 magnitudes is a factor of 100 in brightness, and every tenfold increase in distance adds exactly 5 magnitudes. The naked-eye limit is around magnitude 6 in dark skies and closer to 4 in a city.

Farther away always looks dimmer

The distance modulus formula converts a star's true (absolute) brightness into how bright it looks from a specific distance — light spreads out and fades the farther it travels, so distance alone changes apparent brightness dramatically.

Remember: lower numbers mean brighter

The magnitude scale is famously backwards from intuition — it's logarithmic and inverted, so the brightest visible stars have small or even negative magnitudes, while faint telescope-only objects have large positive numbers.

Frequently asked questions

A star has absolute magnitude +1.0 and is 100 parsecs away — what is its apparent magnitude?

m = M + 5 × log10(d/10) = 1.0 + 5 × log10(100/10) = 1.0 + 5 × 1 = 6.0. It would be barely visible to the naked eye (limit is about 6.5).

How is apparent magnitude different from absolute magnitude?

Apparent magnitude is brightness as seen from Earth (distance-dependent). Absolute magnitude is brightness at a standard 10 parsecs (intrinsic). Use the absolute magnitude calculator to remove distance effects and compare stars fairly.

What is the apparent magnitude of the Sun?

About -26.7, by far the brightest object in our sky. Sirius, the brightest nighttime star, is -1.46. The full Moon is about -12.7. Each 5-magnitude difference is a factor of 100 in brightness.