About FAQ

๐Ÿ”ญBortle Scale Estimator

Estimate your sky's Bortle class via questionnaire, SQM reading, or the reference table.

Can you see the Milky Way overhead?
Is light pollution / sky glow visible near the horizon?
Can you see the Andromeda Galaxy (M31) with the naked eye?
Are faint meteors easily visible during a shower?

This is an approximate, subjective estimate โ€” not a precise photometric measurement. For precision, use a real Sky Quality Meter or a satellite light-pollution map. Nothing here is stored beyond this session.

Free Bortle Scale Estimator

How dark is your sky, really? Our free Bortle scale estimator helps you figure out where your stargazing spot falls on the 9-level Bortle scale โ€” from pristine class 1 dark-sky sites where the Milky Way casts shadows, to washed-out class 9 inner-city skies where only the brightest stars are visible. Answer a few simple questions about what you can see overhead, and get an instant estimate of your class.

Already know your Sky Quality Meter (SQM) reading? Enter it directly for a more precise match. Prefer to browse instead? A full reference table describes every Bortle class, its typical limiting magnitude, and what you should expect to see at each level.

No sign-up, no downloads, no limits โ€” just a clearer picture of your night sky. See the About page or the FAQ for more.