Science & Engineering Calculators

Physics, chemistry, electrical and weather formulas with units handled for you, from Ohm's law to molarity and dew point.

18 calculators · Formulas shown · Free

Electrical & engines 6

Ohm's Law Calculator Any two of volts, amps, ohms and watts give the other two. Electricity Cost Calculator Appliance kWh and running cost per day, month and year. Resistor Color Code Calculator Color bands to ohms and back, plus series and parallel resistance. Voltage Drop Calculator Volts and percent lost in a cable run, and the smallest wire for your target. Horsepower Calculator Horsepower from torque and rpm or work and time, and hp, PS and kW conversions. Engine Horsepower Calculator Horsepower estimates from quarter-mile ET or trap speed, and wheel vs crank hp.

Physics & chemistry 7

Density Calculator Solve ρ = m/V for density, mass or volume, with a table of common densities. Mass Calculator Mass from density × volume or dimensions, with weight on Earth. Weight Calculator Weight force from mass (W = m × g), on Earth and other planets. Speed Calculator Speed, distance or time from the other two, plus pace per km and per mile. Molarity Calculator Molarity, grams to weigh out, and C₁V₁ = C₂V₂ dilutions. Molecular Weight Calculator Molar mass and mass percentages from any chemical formula. Half-Life Calculator Radioactive decay: amount left, time elapsed or half-life.

Weather 3

Wind Chill Calculator Feels-like temperature from air temperature and wind, with frostbite times. Heat Index Calculator Feels-like temperature in hot, humid weather, with NWS caution levels. Dew Point Calculator Dew point from temperature and humidity, or humidity from dew point.

Networking & data 2

IP Subnet Calculator IPv4 network, broadcast, host range and masks, subnetting and IPv6. Bandwidth Calculator Download time, speed needed, website bandwidth and Mbps ↔ MB/s.

Units and accuracy

Physics and chemistry formulas only work when the units are consistent, so these calculators convert units for you and show which ones they use. Constants such as standard gravity are the internationally agreed values. Electrical results are for planning and learning; wiring must follow your local electrical code and be done by a qualified person where required.