A kW is a flow rate, a kWh is a volume. The first tells you how fast energy is moving, the second how much of it moved in total. Mixing them up is not a vocabulary slip: in Belgium the two units are billed separately, and the gap runs into hundreds of euros a year.
A flow rate on one side, a volume on the other
Think of a tap. The flow rate is the number of litres per minute coming out of the pipe: that is the kilowatt. The volume is what sits in the bucket at the end: that is the kilowatt-hour.
The kilowatt (kW) measures power, meaning a quantity of energy transferred per unit of time. The kilowatt-hour (kWh) measures energy, meaning power multiplied by a duration. One kilowatt sustained for one hour makes one kilowatt-hour. That is the whole relationship, and it fits into a single multiplication.
Hence the conversion rule you will use every day: power × time = energy. An 11 kW charge point plugged in for two hours has delivered 22 kWh. A 3.7 kW charge point plugged in for six hours has delivered 22.2 kWh, the same thing in three times the time.
Where do you actually see kW and kWh on an electric car?
Everywhere, and that is precisely the problem: an EV spec sheet lines up four different units in twelve rows without ever telling you which one does what. Here is the mapping.
| Unit | What it measures | Where you read it | Belgian order of magnitude |
|---|---|---|---|
| kW | Power: a flow rate | Motor output, charge point rating, Flemish meter peak | 3.7 to 22 kW at home, 50 to 350 kW on public charging |
| kWh | Energy: a volume | Battery capacity, meter index, charging receipt | 22 to 118 kWh of battery, ~3,500 kWh/year for a Belgian household without an EV |
| kWh/100 km | Consumption | Spec sheet, trip computer | 14 to 24 kWh/100 km in real-world use |
| kVA | Apparent power | Grid connection contract, fuse board | 9.2 kVA on a standard 40 A single-phase meter |
| c€/kWh | Price of energy | Electricity bill, public charge point | 32.22 to 37.83 c€ at home (CREG, Q3 2026) |
| €/kW/year | Price of power | Grid fee line, Flanders only | €52 to €60 per kW of peak per year |
Three of those six rows exist in this form only in Belgium. That is what makes the French guides currently occupying the first page of Google.be more or less unusable here.
The pair that matters most when you buy: the kWh in the battery decide the range, the kW of the charge point and of the onboard charger decide the charging time. A big battery on a small onboard charger means a whole night at the end of the cable.
How many kWh does 100 km take, and what does that cost in euros?
Between 14 and 24 kWh per 100 km depending on the car, the speed and the season. This is the one conversion that really matters, because it turns an abstract unit into a budget line.
The table below crosses consumption figures actually measured on the road by Automobile Propre with the reimbursement caps published by CREG, the Belgian federal energy regulator, for the third quarter of 2026. Those caps are currently the cleanest published figure for the price of a home kWh by Belgian region.
| Measured real-world consumption | Reference model | Flanders (32.22 c€) | Brussels (35.68 c€) | Wallonia (37.83 c€) |
|---|---|---|---|---|
| 14.0 kWh/100 km | Tesla Model 3 RWD | €4.51 | €5.00 | €5.30 |
| 15.0 kWh/100 km | Ford Explorer Electric, secondary roads | €4.83 | €5.35 | €5.67 |
| 17.0 kWh/100 km | BYD Dolphin, mixed use | €5.48 | €6.07 | €6.43 |
| 23.2 kWh/100 km | BMW iX1 xDrive30 | €7.48 | €8.28 | €8.78 |
Two lessons come out of that table, and neither appears in the generic guides. First, the same kilowatt-hour does not cost the same on both sides of the language border: 5.61 c€ between Flanders and Wallonia, which is €190 a year over 20,000 km at 17 kWh/100 km. Second, the gap between a city car and a premium SUV, €5.48 against €7.48 per 100 km, stays around €400 a year, while the range gap gets paid every single day in charging stops.
In practice, if you want one mental rule: divide the battery capacity by the consumption, multiply by 100. A 60 kWh battery at 17 kWh/100 km gives 353 km. That is more reliable than any WLTP figure.
In Belgium the kW is billed separately, and that is the real trap
This is the point French articles cannot cover, because it does not exist there. Since January 2023, Flanders charges part of its grid fees on the peak power recorded by the digital meter, not on the energy consumed. The highest quarter-hour of the month, averaged over twelve months, multiplied by a rate between €52 and €60 per kW depending on the grid operator.
The kilowatt therefore becomes a product you buy by the year, independently of the kilowatt-hour.
Run the numbers on home charging. A Flemish household peaks at 4.24 kW on average according to Fluvius, the Flemish grid operator. Plug in an 11 kW charger while the house is busy and the peak climbs to 11 kW and beyond. Plug the same car into 3.7 kW overnight and it stays below 5 kW. Same car, same kilometres, exactly the same number of kilowatt-hours in the battery: 7.3 kW more peak, which is €380 to €440 a year. The countermeasures (overnight scheduling, dynamic load balancing, a power ceiling) are covered in our feature on the Flemish capacity tariff.
Four expensive mistakes all trace back to the same confusion:
- Buying a 22 kW charge point for a car that accepts 7.4 kW. The onboard charger sets the ceiling; the remaining 14.6 kW will never be used.
- Believing that faster charging consumes more. The number of kWh transferred is identical; only the duration changes. What also changes, in Flanders, is the peak you get billed for.
- Comparing a public charge point priced per kWh with one priced per minute. Per-minute billing penalises cars that take few kW: at €0.59 a minute, a car charging at 50 kW pays twice as much per kWh as a car charging at 100 kW.
- Reading "150 kW" on a charge point and expecting it from your car. The charge point advertises its maximum, the car accepts its own, and the figure that applies is always the lower of the two.
And what about the kVA on the meter, is that yet another thing?
Yes, and it is the third unit in the family: the one that shows up on your grid connection contract and never on the car. The kilovolt-ampere (kVA) measures apparent power, meaning the raw product of voltage and current, before accounting for the phase shift between them.
In a house, the gap between kVA and kW is small: the power factor of a modern domestic installation is above 0.95, so 9.2 kVA is roughly 8.7 usable kW. The standard Belgian meter is exactly 40 A single-phase at 230 V, which is 9.2 kVA. A three-phase 3×230 V connection at 40 A rises to 15.9 kVA, and a 3×400 V one to around 27.7 kVA.
That number becomes concrete the day an electrician works out whether your installation can take a wallbox. An 11 kW charger on a 9.2 kVA meter is mathematically impossible without throttling the charge or upgrading the connection. And Brussels adds a layer: on the 3×230 V networks without neutral that still dominate the city, a three-phase charge point advertised at 11 kW only delivers 6.4, as set out in this piece. Any work on the fuse board is a job for a certified electrician, and the installation must pass inspection by an approved body before being energised.
The serious objection: people drive perfectly well without knowing any of this
It holds. Tens of thousands of Belgians have driven electric for years without ever separating a kW from a kWh, and their cars run fine. The trip computer shows kilometres, the app shows a percentage, and nobody wakes up thinking in SI units.
The nuance comes down to two moments. The day you choose a charge point, and the day you read a Flemish bill. That is where the ignorance has a price, and it has three digits.
Frequently asked questions
What is the difference between kW and kWh in one sentence?
A kW is a speed, a kWh is a distance. A charge point delivers kW, your battery stores kWh, and the second is the first multiplied by time. A 7.4 kW charger plugged in for three hours has moved 22.2 kWh into the battery.
How many kWh does it take to drive 100 km in an electric car?
Between 14 and 24 kWh depending on the car, the speed and the season. A Tesla Model 3 RWD sits around 14 kWh/100 km, a BYD Dolphin around 17 in mixed use, a BMW iX1 xDrive30 around 23 in Automobile Propre's measurements. At Belgian home electricity rates that works out at €4.50 to €8.80 per 100 km.
Is the kVA on my meter the same thing as a kW?
Almost, and the gap is negligible in a home. A kVA measures apparent power, a kW measures the power actually consumed; in a modern domestic installation the ratio between the two is above 0.95. The kVA sizes your grid connection, the kW is what gets billed as your peak in Flanders.
Does a more powerful charge point always charge my car faster?
No. The car sets the ceiling, and it is often lower than the charge point's. A Citroen e-C3 accepts 7.4 kW on alternating current: plugged into a 22 kW charge point, it charges at exactly the same speed as on a 7.4 kW one. Check your car's onboard charger rating before buying the wallbox, not the other way round.
Le verdict de Christophe F.
Keep three reference points and you will not be caught out again. One: the kWh is what you buy, the kW is how fast it arrives, and one kilowatt sustained for one hour makes one kilowatt-hour. Two: in Belgium those two units land on two distinct lines of the bill, and one of them, the €52 to €60 per kW of peak power in Flanders, has no equivalent in the French guides that occupy the first page of Google. Three: before buying a wallbox, look at your car's onboard charger rating, not the power printed on the wallbox box. The model pages give that figure for every version sold here.
