Firmakalk
17 toolsVAT, margin, hourly rate, invoicing, due dates, late-payment interest and employer cost. Norwegian rates, with an open source for every figure.
firmakalk.noThe tool sites
Thirteen websites. 203 calculators. All live now.
This is not client work. These are nine Norwegian tool sites I built, launched and run myself. They are here because they are the simplest way to see what I actually deliver: open any of them and try it, without asking me first.
Every number on this page is counted, not estimated. Tool counts come from each domain's own sitemap, cross-checked against its tool index, verified on 10 August 2026.
- 13
- websites
- 203
- tools
- 403
- pages in total
The sites
Open them and try them.
All nine answer over HTTPS with a valid certificate, on both apex and www. Each has its own sitemap and robots.txt, and the first four are the ones that matter most to a business.
Lønnsoversikt
11 toolsTake-home pay, holiday pay, overtime and employer cost, calculated with the rates that apply in 2026.
lonnsoversikt.noBoligverktøy
13 toolsRent indexation, rental yield, cash flow, document duty, equity requirements, deposits and indicative tax on letting.
boligverktoy.noLåneoversikt
10 toolsCalculators for loans, interest and repayment, explaining what the number means rather than only giving the answer.
laneoversikt.noEnergiSmart Norge
16 toolsElectricity use, solar panels, heat pumps and insulation. You enter your own electricity price, and every assumption can be changed.
stromkalk.noStudentKlar
21 toolsGrade averages, school points and admission points under the current rules, plus planning for reading, absence and budget.
studentklar.noNavneLykke
22 toolsNorwegian baby names with figures from Statistics Norway. What is rising and falling, plus due-date and age calculators.
navnelykke.noFestPlan Norge
17 toolsWeddings, confirmations, anniversaries and company parties. Budget, guest list, seating plan, food and drink, stored in your own browser.
festhjelp.noPakkeklar
20 toolsA packing list matched to the trip. Baggage weight, cabin versus checked, travel budget, time difference and daylight hours.
pakkesjekk.noFilverktøy
21 toolsPDF and images: compress, convert, merge and split. Files never leave the browser, so nothing is uploaded and nothing is stored.
filverktoy.noOppussingskalkulator
15 toolsPaint, concrete, flooring, tiles, wallpaper, decking and insulation. Counts whole packs, and returns a shopping list and a budget.
oppussingskalk.noBilkostnad
12 toolsWhat a car actually costs per month: depreciation, car loan, fuel, tolls and insurance. Compares two cars side by side.
bilkostnad.noSmartFerie
8 toolsPlaces your holiday days where they yield the longest unbroken time off, using weekends and Norwegian public holidays. Covers 2026 to 2035.
smartferie.noFor your business
Want a tool like this on your own site?
The same machinery can be built into your website, in your design. A salary calculator, a price calculator or a rate overview, with the rates maintained in one place instead of typed into the copy.
This is a commission, and it is priced like one. Tell me what you need and you get a fixed price before we start.
How they are built
The invisible layer, across nine sites at once.
Building one site that works is one thing. Thirteen sites that all have to hold the same standard, without anyone watching over them every day, is a different job. That is the interesting part here.
No sign-in, no account, no database
The calculation happens in your browser. The numbers you type never leave your machine. That is not a privacy promise somebody has to keep, it is a consequence of how the sites are built.
One address per tool
Every single tool has its own URL, its own title and its own meta description. That means it can be found in Google on its own, independently of the other tools on the same domain.
Rates are versioned
Every rate carries a validity period, a source and a date it was checked. A new rate is added as a new period, an old one is never overwritten. The date activates the change, not the deployment, so a rate taking effect on 1 May does exactly that.
Source and check date are visible
Every page shows where the figure comes from and when it was last checked. All nine have a privacy policy, terms, a contact page and an about page, not because it looks tidy, but because a page that calculates your tax should be answerable for it.
Statically generated, one project per site
Built in Next.js and shipped as finished files, one Vercel project per site. No server that can go down mid-calculation, and no shared fault that takes out all nine at once.
Verification
The error you cannot find is the one you worked out yourself.
The 2026 rates are checked against primary sources at the Norwegian Tax Administration and NAV. That covers bracket tax, national insurance contributions, employer's contributions by zone, the minimum standard deduction, the national insurance base amount of NOK 136,549 from 1 May 2026, and the 12 G ceiling for mandatory occupational pensions.
The formulas were tested with a method where one party derives the expected answer from the public source without seeing the code, while another runs the code without seeing the expected answer. Only then are the two compared. The point is simple: nobody should be able to confirm their own assumption.
The method found and fixed 18 real calculation errors. Among them a sign error in the battery-bank calculation, an equity requirement missing the debt ratio, and a currency comparison that was a hundred times too large. Rounding was reworked at the same time, so that net plus VAT always equals gross exactly, and so that splitting rent adds up to the øre.
What do you need to make work?
Send a short description of the project or what you want managed better. I will explain what is possible, what needs clarification, and agree a fixed scope and price before work starts.