Science & Nature Tools

Free science and nature calculators that run in your browser — escape velocity and centripetal acceleration, Earth's curvature, moon phases, golden hour times, the date of Easter, and country size comparisons. Nothing is uploaded, and there is no account or sign-up.

12 tools available

Centripetal Acceleration Calculator

Centripetal acceleration calculator: instant m/s² & g-force.

Country Size Compare

Drag country outlines to compare their true size on a map

Earth Curvature Calculator

Horizon distance, drop & hidden height from curvature.

Easter Date Calculator

Easter Sunday's date for any year, Gregorian or Orthodox

Escape Velocity Calculator

Escape velocity from mass & radius, with planet presets

Golden Hour Calculator

Morning & evening golden hour times, with live countdown

Moon Phase Calculator

Moon phase, illumination % & age for any date, instantly.

Moon Phase Calendar

Moon phase for any month, with dark sky days highlighted

Star Trail Calculator

Longest shutter speed before stars trail: 500 & NPF Rules.

Sunrise & Sunset Times

Sunrise, sunset, daylight hours and twilight for any place

Terminal Velocity Calculator

Terminal velocity in m/s and km/h from mass, area and drag

Time Dilation Calculator

Moving vs stationary clock time at near-light speed

Every tool runs in your browser — no upload, no account, free.