Free Online Tools

Calculate basic, complement, union, intersection, conditional, and binomial probabilities with formulas and step-by-step work.

Calculate combinations nCr and permutations nPr with factorial formulas, step-by-step work, and support for large results.

Calculate sample and population standard deviation and variance from any data set with squared-deviation steps.

Calculate orbital period from altitude or radius using Kepler's third law. Presets for ISS, geostationary orbit, Moon, and Earth around the Sun. Free, browser-based.

Calculate blackbody peak wavelength, Stefan–Boltzmann flux, and Planck spectral radiance from temperature. Wien's law and σT⁴. Free, browser-based physics tool.

Convert between earthquake magnitude scales — Mw, Ms, ML (Richter), mb, and Md. Estimates seismic moment, energy in joules, and TNT equivalent. Free, browser-based.

Calculate heat index (feels-like temperature) from air temperature and relative humidity. Uses the official NWS Rothfusz formula with heat risk guidance. Free, browser-based.

Calculate dew point from temperature and relative humidity, or find RH from temperature and dew point. Shows vapor pressure, absolute humidity, and comfort level. Free, browser-based.

Calculate relative humidity, dew point, wet-bulb temperature, vapor pressure, absolute humidity, and mixing ratio from dry-bulb readings. Free, browser-based.

Estimate your annual carbon footprint from car travel, flights, home electricity, and natural gas. Compare to global averages with regional grid factors. Free, browser-based.

Analyze temperature and precipitation climate data. Paste daily or monthly values to get mean, min, max, std dev, heating/cooling degree days, wet days, dry spells, and Northern Hemisphere seasonal summaries (DJF, MAM, JJA, SON). Free, browser-based.

Convert microliters (µL) to milliliters, liters, nanoliters, cubic centimeters, and more. Instant lab volume conversions with all units shown at once. Free, browser-based.