Physics Unit Converter

A physics unit converter handles the common SI and non-SI units in one place: force (N, dyne, lbf, kgf), energy (J, eV, cal, kWh, BTU), pressure (Pa, atm, bar, mmHg, psi), and many others. You select the source unit, enter the value, and choose the target unit. So 1 horsepower converts to 745.7 W, 1 atm to 101325 Pa, 1 eV to 1.602×10^8¹ J. The tool saves you from memorising dozens of conversion factors and avoids the slipups that creep in when chaining several conversions by hand. Especially useful when textbook units don't match exam units.

1 newton ≈ 0.2248 pounds-force, and 1 pound-force ≈ 4.448 N. So a 100 N force is about 22.5 lbf, while a 50 lbf weight is roughly 222 N. The conversion comes from g = 9.80665 m/s² in metric versus a separate definition based on Earth gravity in imperial. Engineers in the US often work in lbf, while everyone else uses newtons. The converter handles it instantly, but knowing the rough factor of 4.45 gives you sanity checks. Useful when reading mixed-unit specifications or converting tensile strength data between regional standards.

1 electron-volt = 1.602×10^8¹ joules. So small atomic and molecular energies, awkward in joules, look much friendlier in eV. The hydrogen ionisation energy is 2.179×10¹ J, but a clean 13.6 eV. Conversely, 1 J = 6.242×10^14 eV. The eV is the natural energy unit at the atomic scale because it's the kinetic energy gained by one electron crossing a 1-volt potential difference. Calculators flip between J and eV instantly. For nuclear and high-energy physics, you'll often work in keV, MeV, or GeV — each is just a thousandfold step up the same ladder.

1 psi (pound per square inch) ≈ 6894.76 Pa, and 1 Pa ≈ 0.000145 psi. So atmospheric pressure of 101325 Pa is about 14.7 psi, which is why tyre pressure gauges are calibrated in that range. Engineering uses psi extensively in the US; physics and most science worldwide use pascals or kilopascals. Hospital blood pressure cuffs in mmHg add another conversion: 1 mmHg ≈ 133.32 Pa. Calculators handle all of these. When working through a problem, pick one unit early and stick with it — slipping between psi and Pa mid-calculation is a recipe for confused answers.

1 tesla = 10000 gauss, exactly. SI uses tesla; the older CGS system uses gauss. So Earth's magnetic field, around 50 microtesla, is also about 0.5 gauss. A typical fridge magnet is around 0.005 T or 50 G. MRI machines run at 1.5 to 7 T, equivalent to 15000 to 70000 G. The conversion is a clean factor of 10, easy enough to do mentally, but a calculator removes any risk of slipping a zero. Engineers and physicists working with magnetic field measurement instruments often switch between the two depending on equipment and tradition.

1 elementary charge e ≈ 1.602×10^8¹ C. So 1 coulomb equals about 6.242×10^14 elementary charges — roughly six and a quarter quintillion electrons' worth. A lightning bolt carries about 15 C, equivalent to nearly 10² electrons. Calculators handle the conversion both ways, useful when problems involve actual electron counts (like in current calculations, ionisation processes, or capacitor charge buildup). The elementary charge is the natural unit in atomic and particle physics, while the coulomb is everyday-scale and aligns with ampere-seconds in electrical engineering. Both describe the same physics, just at different scales.

A solid SI converter recognises base units (kg, m, s, A, K, mol, cd) and derived units (N, J, W, Pa, V, Ω, T, etc.), along with prefixes from yocto (10²) up to yotta (10²). So 5 GHz becomes 5×10 Hz, 25 mN becomes 0.025 N, 3 µT becomes 3×10^-6 T. The calculator handles compound units too — speed, acceleration, energy density, anything constructed from the base set. Especially helpful in problem-solving where input data come in mixed prefixes and the formula expects pure SI. Convert everything up front, then compute, then convert back to whatever the question demands.