Mortgage calculator

Mortgage calculator: run smarter mortgage scenarios (and understand the numbers)

A mortgage is rarely just “interest times loan”. In Sweden, your monthly cost is affected by the down payment, loan-to-value (belåningsgrad), mandatory amortisation (amorteringskrav) and sometimes the debt-to-income add-on. A mortgage calculator helps you test scenarios quickly, prepare for the bank meeting, and most importantly stress-test that your budget holds up.

This guide helps you:

• understand what the calculator actually computes
• read the results (interest vs amortisation)
• do a simple stress test using a kalkylränta
• avoid common mistakes when comparing options

Start with the right inputs

The output is only as good as the numbers you put in. A solid starting point:

• Property price: use the purchase price. If you plan to borrow for renovations, you can include that portion (as long as the bank allows it as part of the mortgage).
• Down payment (kontantinsats): how much cash you contribute upfront.
• Interest rate: enter your expected rate or a higher kalkylränta to stress-test.
• Household gross income: total gross per month for everyone on the loan.
• Repayment period: used to estimate total interest cost over time (useful for comparisons).

Tip: If you’re comparing two homes, keep the same rate and income and only change price/down payment. You’ll see clearly how belåningsgrad and amortisation thresholds change the monthly cost.

The 85% bolånetak is a hard line

Sweden has a bolånetak (mortgage cap): a typical bolån may not exceed 85% of the property price. In practice:

• You need at least 15% down payment to stay under 85%.
• If you end up above 85%, you usually need to increase the down payment or use other financing (e.g. an unsecured loan), which can be much more expensive.

In the calculator this shows as loan-to-value / belåningsgrad. If it lands above 85%, treat it as a clear signal to adjust the setup.

Amorteringskrav: why 50% and 70% matter

Amortisation isn’t only “paying off faster”. In Sweden it can be mandatory. A common simplification is:

• Belåningsgrad 50–70% → at least 1% per year amortisation
• Belåningsgrad above 70% → at least 2% per year amortisation

On top of that, there is often an add-on:

• Debt-to-income above 4.5× (loan compared to household annual income) → extra 1% per year

The point: Two households with the same loan can have very different monthly costs depending on income and down payment.

How to read the results (a key distinction)

In the results you’ll see, for example:

• Monthly cost (interest + amortisation)
• Monthly interest cost
• Minimum monthly amortisation
• Total interest over the term and Total paid

Here’s the key distinction:

• The calculator’s monthly cost is interest + the minimum required amortisation.
• That is not always the same as the payment needed to fully repay the loan exactly over the period you enter.

The repayment period is mainly there to compare long-term cost (total interest). In Sweden, amorteringskrav often sets the minimum you must amortise, rather than your chosen term.

Stress-test with a kalkylränta

Banks often use a higher kalkylränta than your current rate in their KALP (kvar-att-leva-på) assessment. You can run a quick stress test:

• Set the rate to a level that feels tough but realistic (for example +2–3 percentage points compared to your “normal” rate).
• Keep the same price and down payment.
• Compare the monthly cost and ask yourself if the budget still holds with margin.

A practical rule of thumb is to never remove your buffer. It’s often when rates rise at the same time as other costs increase (electricity, fees, food, insurance) that the household budget gets squeezed.

Common mistakes when comparing mortgages

• Only looking at the rate: A small discount can help, but belåningsgrad and amortisation can affect the monthly cost just as much.
• Forgetting other housing costs: Fees, operating costs, maintenance, home insurance and electricity aren’t always visible in a pure mortgage calculation. Add a separate “housing costs” line in your own budget.
• Underestimating the impact of the down payment: More down payment can move you below important thresholds (85%, 70%, 50%).
• Mixing gross and net: Debt-to-income is often based on gross income, but your ability to pay depends on what remains after tax and fixed expenses.

Checklist: what to bring to the bank

After testing a few scenarios, write down:

• loan-to-value (belåningsgrad), especially if you’re close to 85%
• minimum monthly amortisation and whether the 4.5× add-on applies
• stressed monthly cost using a higher kalkylränta
• how much buffer you have left in your monthly budget

That makes the conversation about terms, rates and amortisation structure much more concrete.

Important to know

Rules and banks’ internal models can change, and they may also be applied differently depending on your situation. Use the calculator as decision support and always confirm terms and requirements with your bank.