Electrical Engineering Calculators and Formulas

Electrical Engineering Formulas and Calculators

• Ohm's Law Calculator

  V = I R, P = V I

  V voltage, I current, R resistance, P power

  Example: 12 V across 4 Ω drives 3 A and dissipates 36 W.

  Open the ohm's law calculator →

• Wire Resistance Calculator

  R = ρ L ÷ A

  ρ resistivity, L conductor length, A cross-sectional area

  Example: 100 m of 2.5 mm² copper = 0.69 Ω at 20 °C.

  Open the wire resistance calculator →

Unit Converters for Electrical Engineering

• Electrical Resistivity Converter – Ω·m, Ω·cm, µΩ·cm, Ω·mm²/m, MΩ·cm
• Electrical Conductivity Converter – S/m, MS/m, µS/cm, mS/cm, dS/m, %IACS
• Power Converter – W, kW, MW, hp, PS, BTU/h, TR, kcal/h
• Energy Converter – J, kJ, kWh, kcal, cal, BTU, therm, eV
• Frequency & RPM Converter – Hz, kHz, MHz, GHz, rpm, rad/s
• Data Transfer Rate Converter – Mbps, MB/s, Gbps, kbps, MiB/s
• Data Storage Converter – bytes, KB, MB, GB, TB, KiB, MiB, GiB
• Magnetic Flux Density Converter – T, mT, µT, nT, G, mG, kG
• Magnetic Field Strength Converter – A/m, kA/m, A/cm, Oe, kOe
• Magnetic Flux Converter – Wb, mWb, µWb, Mx

Common Electrical Engineering Conversions

• microohm centimetre to ohm metre
• ohm metre to microohm centimetre
• microsiemens per centimetre to millisiemens per centimetre
• millisiemens per centimetre to microsiemens per centimetre
• kilowatt to horsepower
• horsepower to kilowatt
• kilowatt-hour to BTU
• BTU to kilowatt-hour
• revolution per minute to hertz
• hertz to revolution per minute
• megabit per second to megabyte per second
• megabyte per second to megabit per second

Using these electrical engineering calculators

Ohm’s law (V = IR) and the power relations (P = VI = I²R = V²/R) cover most everyday circuit checks. Enter any two of voltage, current, resistance and power and the calculator gives the other two, with milli- and kilo- prefixes handled for you.

Conductor sizing depends on resistivity, length and cross-section. The wire resistance calculator uses R = ρL/A with resistivities for copper, aluminium and other conductors, or a %IACS rating, so you can estimate voltage drop and heating in a cable or busbar before choosing a size. Remember that resistance rises with temperature: copper gains about 0.4 % per kelvin.

The unit converters on this page cover resistivity (Ω·m, µΩ·cm, Ω·cmil/ft), conductivity (S/m, %IACS), power, energy and magnetic quantities such as tesla, gauss and oersted, which are often quoted in CGS units in older data and in SI in newer standards.