How we calculate
What the numbers on this site mean, and what they are not.
Market price
By default you see the market price: the result of the EPEX Spot day-ahead auction for the Netherlands, fetched through the public EnergyZero API. This price is excluding VAT, energy tax and your supplier’s markup. It is the only price we actually measure. The English pages show it in euros per kWh (for example €0.1234 per kWh); the Dutch pages show the same price in cents.
All-in estimate
If you choose ‘All-in estimate’, we calculate for each hour:
(market price + supplier markup + energy tax) × 1.21
The 1.21 is 21% VAT. The markup is 0 by default; enter the purchasing fee from your own contract for a better estimate. Your setting is only stored in your own browser.
| Type | Rate | Incl. 21% VAT |
|---|---|---|
| Electricity (0–10,000 kWh) | €0.09161 per kWh | €0.11085 |
| Natural gas (0–170,000 m³) | €0.60066 per m³ | €0.72680 |
Source: Belastingdienst (Dutch Tax Administration), energy tax (in Dutch, checked on 17 October 2026).
What is not included
- Your supplier’s fixed supply charges.
- Network charges (a fixed amount per month).
- The energy tax reduction: a fixed amount per year per connection (2026: €519.80 excl. VAT). It does not depend on the hour, so we do not deduct it per kWh.
- Quarter-hour prices: some suppliers bill per quarter-hour. We show hourly prices.
So the estimate is an approximation of what one extra kWh costs you in that hour. Your actual bill comes from your supplier.
Why the cheapest time does not change
Tax and markup are the same per kWh in every hour of the day. That is why the cheapest hour stays the same hour in both views. Only the amounts change.
Price class A to G
For each day we divide the range between the cheapest and the most expensive hour into seven equal steps. An hour in class A belongs to the cheapest step of that day, class G to the most expensive. The colours and letters look like the EU energy label, but they are relative to each day: class A is not always cheap in euros. If the prices on a day are close together, we say so.
Times
All times are Dutch local time (Europe/Amsterdam): CET (UTC+1) in winter and CEST (UTC+2) in summer.
The planner
The planner finds the continuous block of hours with the lowest average price. The usage per appliance is an example value that you can change. We calculate as if the appliance uses power evenly; in reality a washing machine uses the most at the start (heating up).