About us

We are not a financial institution, and we are not authorised financial advisors. What we have is years of personal experience — fixing the mistakes in our own finances, and helping friends and family with theirs. The goal is to help you help yourself with your money. A main goal with this site is to learn my kids what we know through this site — whether we're there for them in the future or not.

Simply put: this is not financial advice. An authorised advisor from your bank can help you with the details. We just want to teach you a bit of what we know, and do some of the math for you. Hopefully show you there's a lot you can do yourself — but it's all up to you.

Your data

There is no account, no server and no tracking here. Everything you type is stored only in this browser, on this device — we cannot see it, sell it, or lose it in a breach. We recommend not using this site on a public device. The button at the bottom of the main page downloads a complete copy of everything stored (JSON) whenever you want. You can take that file with you to another device and upload it there — the file is only read into your own browser. If you reset the browser — clearing its stored site data and cookies — the data disappears. When you enter information about your personal finances, you do it right there in the browser you have open. You can delete it afterwards, and everything is gone again. If you want it all gone in one click, the button for that sits at the bottom of this page, under the math section. One caveat: everything may be reset without warning when we upgrade the site — we try to avoid it, but we don't promise.

The math

Everything we do here, you can do yourself if you want to — we have just made it easy for you. Below you'll find the math behind the loan calculator and the savings calculator.

Loan calculator

Interest accrues monthly. The monthly rate is simply the annual rate split into twelve:

r = annual rate / 100 / 12

An annuity loan (the usual kind) has one fixed monthly payment M — principal plus interest, excluding the admin fee — over n months on a balance P:

M = P · r / (1 − (1 + r)^(−n))          (r = 0  →  M = P / n)

A serial loan keeps the principal slice constant instead, so the payment is heaviest in month one and shrinks from there:

principal each month  = P / n
payment(month)        = P / n + balance · r

Every month the simulator runs the same steps, for both loan types:

interest    = balance · r
principal   = annuity: M − interest     serial: P / n
balance    −= principal (+ your extra payment, if any)
fee         = admin fee, charged for every month the loan is open

The fee amount is the one you type into the loan calculator — leave it blank and we count 95 kr a month.

An optional one-time lump sum lands together with the very first payment and knocks the balance down before the first month's interest — the friendliest possible interpretation, on purpose.

The "pay yourself" numbers are just two runs of this loop: one at the bank's pace, one with your extra payment added. The difference in interest and fees is what you'd otherwise hand to the bank instead of to Future You. Two honest guardrails: if a payment doesn't even cover one month's interest we say so outright — the loan never pays off — and the simulation refuses to run past 100 years no matter the input.

Tracked loans move forward on your payment calendar: the balance drops only when a real payment falls due, on your chosen day-of-month, clamped to the last day of short months (the 31st lands on the 28th in February) — so the calculator stays in sync with your bank statement.

Savings calculator

This is plain "calendar math":

months needed  = round UP of (price / monthly savings)
treasure date  = today + that many months, same day of the month

Rounding always goes up: you arrive with a small buffer, never a small shortfall. The live countdown stores plain days remaining (one month averages 365.25 / 12 days) and simply ticks faster than real time so long horizons feel alive; the math behind the clock stays honest days.