kVA, kW and kWh explained

kVA vs kW vs kWh: what they mean on your business power bill

kWh is how much energy you used; kW is how fast you used it; kVA is the capacity your site demanded. Business bills charge for usage AND demand, so knowing the difference tells you which line to attack.

By Joe Lawrence 23 June 2026 6 min read

No cost to you. We're paid by the energy retailer when you switch.

I’m Joe from Smarta Switch in Brisbane. Three little letters trip up almost every business owner staring at a commercial power bill: kVA, kW, kWh. They look similar, they’re not, and the difference is worth real money. Here’s the plain-English version.

We’re paid by the energy retailer when you switch, never by you.

The one-line version

kWh = how much energy you used (the total). This is your usage.
kW = how fast you were using it at a moment in time (the rate, or power).
kVA = the capacity your site pulled from the grid (very close to kW, but it accounts for how “cleanly” your equipment draws power). This drives your demand charge.

Think of filling a pool with a hose. kWh is the total litres of water that went in. kW is how fast the water is flowing right now. kVA is the size of the hose you demanded to make that flow possible.

kWh, the usage you already understand

A kilowatt-hour (kWh) is one kilowatt of power used for one hour. It’s the unit your usage is billed in: run a 2 kW heater for one hour and you’ve used 2 kWh.

On your bill this is the usage charge: a rate in cents per kWh, multiplied by how many kWh you used in the period. Use less, or use it in cheaper time windows, and this line drops. (How peak/off-peak timing changes this.)

For small, steady sites, usage is most of the bill and kWh is the only unit you really need to watch.

kW, the speed (and why it matters)

A kilowatt (kW) is the rate of power use at an instant. Your usage (kWh) is just kW added up over time.

Why care? Because once a site gets busy, retailers and the network stop only caring how much you used, and start caring about your peak rate, the highest kW (or kVA) you hit. That peak is what the grid had to be ready to deliver for you, even if it only happened for 15 minutes.

kVA, the capacity that triggers demand charges

A kilovolt-amp (kVA) measures apparent power, the total capacity your site drew, including the bit that motors, compressors and fluoro lighting pull but don’t fully convert into useful work (the “power factor” effect).

For sites with a lot of that gear, kVA is higher than kW. And here’s the catch: many commercial tariffs bill the demand charge in kVA, based on your single highest peak in the month. (Demand charges, explained in full.)

So on a demand tariff you’re charged twice over:

Usage (kWh), how much energy you used, and
Demand (kVA or kW), the biggest spike of capacity you pulled.

One bad spike, everything switching on at once on a Monday morning, can set your demand charge for the whole month even if your total usage is modest.

The trap: owners try to cut the bill by “using less” (kWh), but on a demand-tariff site the bigger lever is often flattening the peak (kVA), staggering start-ups so everything doesn’t fire at once.

Which one is costing you?

Pull your bill and look:

A line in kWh? That’s usage. Everyone has this.
A line in kVA (or kW) labelled “demand”? You’re on a demand tariff. That line is often 20 to 40% of the whole bill, and it’s the one most owners can’t explain.
kVA noticeably higher than your kW? That’s a power-factor signal, sometimes fixable with correction equipment on the right site, but first worth checking you’re even on the right tariff. (How Queensland business tariffs work.)

If you’ve got a demand line, that’s usually where the hidden money is, and where a proper review pays for itself.

What to do this week

Find the units on your bill. Circle the kWh line (usage) and any kVA or “demand” line.
If you have a demand charge, note how big it is versus your usage. If it’s a big slice, your peak, not your total, is the thing to manage.
Get it reviewed. Upload your bill on this page or email hello@smartaswitch.com.au. We’ll tell you which unit is driving your cost, whether your tariff suits your usage, and what it should look like. No cost, no commitment, because we’re paid by the energy retailer when you switch, never by you.

Three letters, two very different charges. Once you know which one is hurting, you know exactly what to fix.

Joe Lawrence, Co-founder, Smarta Switch Australia 0435 642 592 · joe@smartaswitch.com.au

Frequently asked questions

What is the actual difference between kVA, kW and kWh?

kWh is how much energy you used in total, which is your usage. kW is how fast you were using it at a moment in time, and kVA is the capacity your site pulled from the grid, which drives your demand charge.

What does kVA mean on my business electricity bill?

kVA measures apparent power, the total capacity your site drew from the grid, including the bit that motors, compressors and fluoro lighting pull but don't fully convert into useful work. Many commercial tariffs bill the demand charge in kVA, based on your single highest peak in the month.

Why does my business bill charge for demand and usage separately?

On a demand tariff you're charged twice over: usage in kWh for how much energy you used, and demand in kVA or kW for the biggest spike of capacity you pulled. One bad spike, like everything switching on at once on a Monday morning, can set your demand charge for the whole month even if your total usage is modest.

How much of my bill is the demand charge?

If you have a line in kVA or kW labelled demand, you're on a demand tariff, and that line is often 20 to 40% of the whole bill. It's usually the line most owners can't explain, and often where the hidden money is.

Why is my kVA higher than my kW?

kVA is higher than kW on sites with a lot of motors, compressors and fluoro lighting, because of the power-factor effect where equipment pulls capacity it doesn't fully convert into useful work. That's a power-factor signal, sometimes fixable with correction equipment on the right site, but it's first worth checking you're even on the right tariff.

Should I focus on using less power or something else to cut my bill?

Owners often try to cut the bill by using less energy, but on a demand-tariff site the bigger lever is usually flattening the peak in kVA by staggering start-ups so everything doesn't fire at once. Using less kWh helps the usage line, but your peak, not your total, is what sets the demand charge.

Does it cost anything to get my bill reviewed?

No, there's no cost and no commitment. You can upload your bill on the page or email hello@smartaswitch.com.au and we'll tell you which unit is driving your cost and whether your tariff suits your usage, because we're paid by the energy retailer when you switch, never by you.