The Black Hole Calculator computes quantities about black holes in two systems of units.
Add the inputs and press Calculate. The outputs in the Standard Mode and the Advanced Mode are:
Standard Mode: Category, Eddington luminosity, Eddington accretion rate, Angular momentum, Event horizon radius, ISCO radius, Photon sphere radius, Bondi radius.
Advanced Mode (in addition): Effective luminosity (considering Eddington ratio and radiative efficiency), Growth time, Hawking temperature, Entropy, Evaporation time, Surface area, Surface gravity.
Try it! The black hole in M87, imaged by the Event Horizon Telescope, has 
, 
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