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Reactive Energy Converter
Convert VARh, kVARh and MVARh, the figures on a commercial electricity bill next to kWh.
Open a household electricity bill and you see kWh. Open a factory or office block’s commercial bill and there is often a second figure sitting quietly next to it, labelled kVARh, that residential customers never see and most people cannot explain.
Reactive power, tracked over time
Reactive power (measured in VAR) is a snapshot — how much of the circuit’s capacity is being used at this instant for power that does no work. Reactive energy is that same quantity accumulated over a billing period, in volt-ampere-reactive-hours, exactly the way kWh accumulates watts over time.
A site running large motors at a poor power factor for hours on end racks up a meaningful kVARh total even though almost none of it shows up as useful output. Utility meters at commercial and industrial connections track it separately for exactly this reason: it is a real cost to the network even without being a real cost in delivered energy.
Reactive energy unit conversion
| From | To VARh | To kVARh | To MVARh |
|---|---|---|---|
| 1 VARh | 1 | 0.001 | 0.000001 |
| 1 kVARh | 1,000 | 1 | 0.001 |
| 1 MVARh | 1,000,000 | 1,000 | 1 |
What shows up on an industrial bill
- Active energy (kWh) — the energy actually consumed and converted into useful work.
- Reactive energy (kVARh) — tracked to work out the site’s average power factor over the billing period.
- A power-factor surcharge, applied automatically once the calculated average power factor drops below the utility’s threshold.
- Peak demand (kW or kVA) — the highest load recorded in any short interval, billed separately from total energy.
Why residential customers never see this
Homes mostly run resistive and lightly inductive loads — heaters, lighting, small appliances — and draw relatively little reactive power compared with an industrial site full of motors, welders and transformers. Metering and billing for reactive energy costs the utility money to implement, so it is reserved for connections large enough that the reactive draw is worth measuring and charging for.
Reactive energy questions
What is the difference between VAR and VARh?
VAR measures reactive power at an instant, the same way watts measure real power at an instant. VARh measures that reactive power accumulated over time, the same way kWh accumulates watts — it is the energy version of the power figure.
Why does my business get charged for reactive energy?
Because a poor power factor forces the utility to deliver more total current for the same useful energy, which strains transformers and cables. Many commercial tariffs include a kVARh charge or penalty specifically to recover that extra infrastructure cost.
How do I convert kVARh to MVARh?
Divide by 1,000. A site that has accumulated 45,000 kVARh over a billing month has used 45 MVARh of reactive energy in that period.
Can reactive energy be negative?
On a meter reading, yes in a sense — capacitive loads produce reactive power of the opposite sign to inductive loads, so some meters separately track leading and lagging reactive energy rather than netting them into one figure.
Does reducing reactive energy lower my kWh bill?
Not directly, since kWh only measures real energy consumed. But improving power factor, usually with capacitor banks, reduces or eliminates the separate reactive energy charge and can lower peak demand charges too.
