Astronomy & Space calculators
Orbits, rockets, telescopes, star magnitudes, planets and astrophotography.
22 free tools
Most used
Orbital Velocity CalculatorCircular orbit speed and period at any altitude above any planetRocket Equation CalculatorDelta-v from mass ratio and specific impulse — or the propellant you needTelescope Magnification CalculatorMagnification, exit pupil, field of view and useful power for any eyepieceWeight on Other Planets CalculatorSee what you would weigh on Mars, the Moon, Jupiter and every planet
More astronomy & space tools
Age on Other Planets CalculatorHow old you would be on Mars, Jupiter, Mercury and every planetAngular Size CalculatorAngular diameter from size and distance — or solve for size or distanceApparent & Absolute Magnitude CalculatorConvert apparent magnitude, absolute magnitude and distance with extinctionLight Travel Time CalculatorHow long light takes to cross any distance — Moon, Sun, Mars or starsOrbital Period CalculatorKepler’s third law: orbital period from distance, or distance from periodParallax Distance CalculatorTurn a star’s parallax into parsecs, light-years and absolute magnitudeSun Position CalculatorSolar elevation and azimuth for any place, date and timeSurface Gravity CalculatorFind the surface gravity of any planet, moon or star from mass and radiusTelescope Field of View CalculatorWork out how much sky an eyepiece or camera sensor shows in your scopeDrake Equation CalculatorEstimate how many civilizations in our galaxy we could detectHabitable Zone CalculatorFind the Goldilocks zone where liquid water could exist around a starHohmann Transfer CalculatorDelta-v and travel time to move between two circular orbitsRedshift & Hubble’s Law CalculatorTurn a spectral line shift into redshift, recession speed and distanceRoche Limit CalculatorFind how close a moon can orbit before tides tear it apartSchwarzschild Radius CalculatorFind how small any mass must be squeezed to become a black holeSidereal Time CalculatorFind local sidereal time to know which stars are on your meridianStellar Luminosity CalculatorWork out how bright a star really is from its size and temperatureTelescope Limiting Magnitude CalculatorSee the faintest stars and finest double stars your telescope can show