Unit conversion looks like the simplest kind of calculator there is — multiply by a fixed number and done — but the two families of converters on this page actually work in different ways, and mixing them up is where mistakes creep in. Converting a weight between kilograms and pounds is a fixed ratio: one unit always equals the same amount of the other, regardless of what is being weighed. Converting electrical power from kVA to amps is not a fixed ratio at all — it depends on the voltage of the supply and, for anything that isn't a simple resistive load, on the power factor of whatever is drawing the current. The calculators below handle both, but they are solving genuinely different problems.
Calculators in this section
Why kVA and kW are not the same number
A generator, UPS or transformer is almost always rated in kVA — kilovolt-amps — which measures apparent power: voltage multiplied by current, nothing more. What a motor, heater or any other load actually consumes and turns into useful work is real power, measured in kW, and the two figures only match when the power factor is 1 — a purely resistive load, like a bar heater. Anything with a motor, transformer or switched-mode power supply draws current that is out of phase with the voltage, which pulls the power factor below 1, typically somewhere around 0.8–0.95 for common industrial and commercial loads. A UPS rated at 10 kVA running equipment at a 0.8 power factor is only delivering 8 kW of real power to that equipment — the other 2 kVA of apparent power still has to be carried by the supply but does no useful work. That gap is exactly why sizing a generator or UPS off its kVA rating alone, without checking the power factor of what it feeds, is a routine way to under-provision capacity.
The amps side of the conversion adds one more variable. A single-phase supply converts as amps = (kVA × 1,000) ÷ volts. A three-phase supply divides that same figure by volts × 1.732 (the square root of three) rather than by volts alone, because three-phase power is split across three live conductors instead of one. Using the single-phase formula on a three-phase supply overstates the current draw by roughly 73%, which is large enough to matter once the result feeds into cable sizing or breaker selection.
Weight conversion has one exact ratio, not the rounded one most people use
Kilograms to pounds looks like it should be simpler, and mostly it is — but the number worth using is the exact one, not the rounded "2.2" most people carry around. The international pound has been defined since 1959 as exactly 0.45359237 kilograms, which makes one kilogram exactly 2.2046226218 pounds. Using 2.2 instead of the full figure introduces a small error that stays invisible for a single conversion and then compounds visibly across a chain of them — converting a training log, a parcel's shipping weight, or a set of dosages in bulk with a rounded factor rather than the exact one.
The stone is the extra wrinkle in a kilograms-to-pounds conversion, used in the UK and Ireland for body weight specifically and rarely for anything else. One stone is exactly 14 pounds, a unit that predates standardised weights and originally referred to specific trade stones used at markets before being fixed by statute. Converting kilograms to stone and pounds is therefore a two-step calculation — kilograms to pounds using the exact ratio above, then dividing that figure by 14 to get whole stones with the remainder expressed in pounds — which is why it gets its own calculator rather than being left to mental arithmetic.