About Kalkulo

Who is behind Kalkulo

Kalkulo is built and run by Erik Sandvik, a Norwegian developer who maintains the entire site alone. There is no editorial team behind this, and I would rather say so plainly than hide it behind a corporate "we". Every calculator, explanation and source reference here is written and checked by one person.

Kalkulo started in the summer of 2026 for a fairly ordinary reason: I was looking for a calculator for a routine calculation myself, and found a page that gave me a number without explaining where it came from — and without saying which year the rate applied to. That makes it hard to know whether the number can be trusted. Kalkulo is my attempt at the opposite.

What this site tries to do differently

• Show the formula, not just the answer. Every calculator explains the arithmetic behind the result, so you can check it by hand if you want to.
• Date the rates. Calculators built on official Norwegian rates — income tax, welfare benefits, BSU savings, holiday pay, property transfer tax — show which year the rate applies to, when it was last verified, and a direct link to the primary source.
• Be honest about the limits. Most calculations simplify something. Where a model has a meaningful limitation, it is written on the page rather than left implied.
• Fix errors quickly. When something turns out to be wrong, it gets corrected — not left standing until an annual review.

A note on the English pages

Many of the calculators here are language- and rule-neutral — maths, physics, unit conversion, construction quantities — and work the same anywhere. Others are specifically about Norwegian rules, and those are named accordingly, with "Norway" in the title, so it is clear from the outset that they model Norwegian law rather than something universal. If a page describes a rate or a legal threshold, assume it is Norwegian unless the page says otherwise.

How the calculators are quality-checked

A source box identifies the source of an explanation or rate; it does not certify the entire calculation model. Source-check dates and model verification are tracked separately. Regression tests can also encode incorrect assumptions. Known model errors are paused until independent reference cases have been checked.

Rates and thresholds for rule-based calculators live in a single, versioned data source in the codebase rather than being written into each individual page. That sounds technical, but it has a practical consequence: when a rate changes, every calculator using it is updated in the same change. The alternative — writing the same rate into ten pages — has already gone wrong in practice here, where one calculator was corrected while a sibling calculator using the same rate was left with the old figure.

The calculation logic has automated regression tests with known inputs and expected outputs, run on every single change to the codebase. There are currently close to 600 such tests. They do not catch everything, but they catch the most common failure: a formula or rate being changed without anyone noticing that a different result broke at the same time.

Rates are verified against the primary source — the Norwegian Tax Administration, NAV, Lovdata, Kartverket, the Directorate of Health — and not against other calculator sites or secondary reference works. That has repeatedly surfaced real errors that would otherwise have been copied onwards.

What I am not

I am a developer, not a tax adviser, lawyer, economist or health professional. Kalkulo does not provide personal advice, and a calculation here does not replace an assessment from someone professionally responsible for your specific situation — particularly for tax, welfare benefits, loans or health.

What I can stand behind is the craft around the numbers: that the rate came from the right place, that the date it was checked is stated, that the formula is documented on the page, and that the calculation is tested. Where you need a binding assessment, go to the agency or professional who can actually give you one.

How the site is funded

Kalkulo is free to use, requires no sign-in, and is funded by advertising. Ads do not influence the numbers any calculator shows, and there is no paid placement in the calculators or the category listings. How data is handled, including what the ad provider loads, is described on the privacy page.