Mortgage calculator — how to figure out what a home really costs

You find a home for SEK 3,000,000. You check the interest rate, do a quick estimate and think “that should be about 6,000 a month.” Then reality lands at almost 13,000.

It happens all the time. The interest rate is only part of the cost — and not even the largest part. A complete calculation includes the interest (obviously), but also the amortisation (amortering) that is mandatory under the Swedish Financial Supervisory Authority’s (Finansinspektionen) rules, the tax deduction (ränteavdrag) that reduces the net cost by 30% on interest expenses up to SEK 100,000 per person per year (21% on the portion above that), the housing association fee (BRF-avgift) if it is a tenant-owned apartment (bostadsrätt), plus electricity and insurance. Miss a single item and the whole calculation is wrong.

What it looks like in practice

Anna and Erik are looking at a two-room apartment in Gothenburg. Asking price SEK 3 million. They have SEK 450,000 for a down payment (kontantinsats) (15%), mortgage SEK 2,550,000, interest rate 2.65%, housing association fee SEK 4,000/month.

Item	SEK/month
Interest (2,550,000 x 2.65% / 12)	5,631
Tax deduction (-30%)	-1,689
Net interest	3,942
Amortisation (2% per year)	4,250
Housing association fee	4,000
Electricity + insurance	~550
Total	~12,742

With a loan-to-value ratio (belåningsgrad) of 85% (above 70%), the Financial Supervisory Authority’s rules require at least 2% amortisation per year. On top of that, the stricter amortisation requirement (skärpt amorteringskrav) applied until recently: if the mortgage exceeds 4.5 times the household’s gross income, an additional 1% is required. For Anna and Erik, with a loan of SEK 2,550,000, this means the extra percentage kicks in if their combined gross income is below approximately SEK 567,000 per year. In that case amortisation becomes 3% instead of 2% — SEK 6,375/month instead of 4,250. (Note: the stricter requirement was abolished on 1 April 2026; only the base requirement based on loan-to-value ratio now applies.)

Amortisation, regardless of the level, is not really a cost. It is forced savings that builds equity in your home. But the money must be paid every month just like everything else, so it shows up in the budget.

The “pure” housing cost excluding wealth accumulation (at 2% amortisation) is SEK 8,492. Not 6,000.

What happens if the interest rate rises?

The bank asks itself this question every time it assesses a mortgage. Their answer is to calculate with a stress-test interest rate (kalkylränta) of around 6–7%. This is part of the affordability assessment (KALP — kvar att leva på), which is the bank’s way of checking that the household can handle all housing costs even at significantly higher interest rates. You should do the same exercise, with your actual budget.

Interest rate	Net interest/month	Total cost/month
2.65% (current)	3,942	12,742
4.00%	5,950	14,750
5.00%	7,438	16,238
6.50%	9,669	18,469

The tax deduction in the table above is calculated at 30%. This holds as long as the household’s total interest expenses do not exceed SEK 100,000 per person per year. At 6.50% interest the annual interest cost is approximately SEK 166,000. Two borrowers can split that amount and stay below the threshold, but for a single borrower the portion above SEK 100,000 would only give a 21% deduction, resulting in a somewhat higher net cost.

From current levels to 5% interest — not unreasonable historically — the monthly cost increases by roughly SEK 3,500. Where is that money in your budget?

Fixed or variable?

75% of Swedish mortgage holders have variable-rate loans — the highest share ever recorded according to Statistics Sweden (SCB). It is not surprising that variable rates are popular: historically, variable rates have often been cheaper. But between 2022 and 2023, the average variable mortgage rate rose from below 2% to nearly 5% in just over a year. Anyone who had locked in a fixed rate in 2021 slept more soundly. There is no right answer. It depends on your buffer, your risk tolerance, and whether you can sleep if the rate takes off next year.

The rules changed on 1 April

Two weeks after this text was originally published, mortgage rules changed. The mortgage ceiling (bolånetak) was raised from 85 to 90%, meaning the minimum down payment was lowered from 15 to 10%. The stricter amortisation requirement (based on debt-to-income ratio, or skuldkvot) was abolished. At the same time, supplementary loans (tilläggslån) were limited to 80% of the property’s value. These changes affect the calculation for anyone buying a home after 1 April, especially the down payment and amortisation level.

A good calculator brings interest, amortisation, tax deduction, fees, operating costs (driftkostnader) and transaction costs together in one place. In BoKalk you can also stress-test at any interest rate level and adjust all parameters until you see the full picture.

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Christoffer, founder BoKalk