Method and sources

The formula

On a spot contract the all-in price per kilowatt-hour is (exchange price × 1.255) + margin + transfer fee + electricity tax. The exchange price is converted from euros per megawatt-hour to cents per kilowatt-hour by dividing by ten, and 25.5% VAT is added, including when the price is negative. Margin, transfer fee and tax are already VAT-inclusive. On a fixed contract the contract’s fixed price replaces the exchange price and margin. Example: 50 €/MWh is 6.2750 c/kWh with VAT; a margin of 0.51 c, Helen’s general transfer of 4.72 c and electricity tax of 2.9179 c give 14.42 c/kWh in total.

Exchange prices

Day-ahead prices for the Finnish bidding zone (FI), quarter by quarter, are fetched from Nord Pool’s public price interface. The updater uses the ENTSO-E Transparency Platform first once it has an access key. Prices are archived daily by Finnish calendar day. The update runs automatically three times a day: in the afternoon after tomorrow’s prices are published, an hour later and at midnight. Your browser also reads the latest price file whenever the page opens.

Average-price estimate when the day’s prices are missing

If the day’s prices are unavailable, the calculator shows an estimate and marks it clearly. When the archive holds at least eight days of the same month and type of day (weekday or weekend) from the past year, the estimate is their quarter-by-quarter average. Otherwise it is the official average for the same calendar month over the last 12 months (Nord Pool monthly aggregates) plus the daily profile for that type of day, i.e. each quarter’s average deviation from the daily mean on archived days (16 August 2026 – 17 October 2026, 63 days). The archive grows every day, so the estimate sharpens over time.

Transfer fees

The calculator covers 72 of the Energy Authority’s 76 distribution operators: every one whose household price list is published as a readable page or PDF including VAT. It includes general transfer, time-of-day or night transfer and seasonal transfer, basic fees by main fuse and household products with a power fee (3 networks). Each product’s time bands are copied word for word from the operator’s price list: hours (usually 07–22, 06–22 in some networks), weekdays (Mon–Sun, Mon–Sat or Mon–Fri) and the winter months of seasonal products. Prices were read on 16 October 2026, and scripts/data/tarkista-verkot.py checks every price and time-band text against its source.

Public holidays are separated from winter weekdays as each price list words it. Holidays come from the official calendar (New Year’s Day, Epiphany, Good Friday, Easter, May Day, Ascension, Whitsun, Midsummer Day, All Saints’ Day, Independence Day, Christmas Day and Boxing Day, Nordic Council of Ministers: public holidays in Finland). Where the price list limits winter time to working days, a weekday holiday counts as other time (Oulun Energia); where it says holidays belong to the winter weekday, they count as winter time (Tampereen Sähköverkko, Keminmaan Energia ja Vesi). Elsewhere the price list names weekdays only, and the calculator follows them as written. The operator for a postcode comes from the Energy Authority comparison service API.

Missing operators (4): Rantakairan Sähkö Oy, Paneliankosken Voima Oy, Muonion Sähköosuuskunta, Tornion Energia Oy. Their price list is not published in readable form, or shows only prices without VAT or with electricity tax included; you can enter their prices under Other operator.

Taxes and defaults

Electricity tax is 2.24 c and the security-of-supply fee 0.085 c per kilowatt-hour before VAT from 1 April 2026, 2.325 c in total and 2.9179 c with VAT. VAT is 25.5%. The default margin of 0.51 c/kWh is the median of 5 consumer spot contracts in the Energy Authority comparison, and the default fixed price of 8.13 c/kWh is Statistics Finland’s average household energy price (5,000–15,000 kWh a year, 2026-06) with VAT. They are starting values to replace with your own contract’s figures.

What the calculation leaves out

The calculation does not know your own quarter-hour load profile, retailers’ special terms (price caps, discounts), solar export or operators’ temporary refunds. The annual comparison assumes even use within each month. Results are estimates; your bills decide.

Tests

The engine tests compute hand-checked cases: the tax-and-VAT combination, the number of quarters on clock-change days, day and winter window boundaries, public holidays and how each network treats them, the cheapest window, the annual comparison and the average-price estimate, built and read as on the site, including when the day’s prices are missing entirely or the source is down. They run at every update before publication.

Sources

Questions and corrections: contact@oikeasahkonhinta.fi.

Frequently asked questions

Why does the calculator differ from my bill?

Usually for one of three reasons: your contract is priced by the hour or by the monthly average rather than by the quarter hour, your retailer’s margin or monthly fee differs from the calculator’s, or your network operator has changed its price list. Compare the bill line by line and enter your own figures. If you think a transfer fee is wrong, write to us.

How often are transfer fees updated?

Operators usually change prices at the start of the year or in summer, and must announce changes in advance. The check script downloads every price list and flags any calculator price missing from it. A corrected price appears on every page at once and the page date changes.

What happens if the day’s prices cannot be fetched?

The calculator shows an average-price estimate and says so in amber. The estimate is the quarter-by-quarter average of actual prices for the same month and type of day, or, until there are enough of those, the official monthly average plus the daily profile. Real prices replace the estimate automatically.

Written by

Radif Partners

Updated · Editorial policy · Contact

Prices and taxes 2026, checked