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What interest on pocket money comes to

Interest on pocket money sounds like very little. In the first year it is. We show the figures anyway, because they only get interesting over years.

How it's worked out

The rate is per year. Each week counts a fifty-second of it. It's worked out on the balance at the start of the week, not on what's in there at the end. So the first week earns nothing. At the start, the account was empty.

An example

A child puts five francs into Saving every week, at a rate of 3 per cent. A year here is 52 weeks, which is a few days short of a calendar year.

  • After 52 weeks

    Contributed CHF 260.00
    Interest CHF 3.86
    Balance CHF 263.86

  • After 260 weeks

    Contributed CHF 1'300.00
    Interest CHF 102.13
    Balance CHF 1'402.13

  • After 520 weeks

    Contributed CHF 2'600.00
    Interest CHF 431.10
    Balance CHF 3'031.10

The bar shows a row's interest against the last row's. That is why the first one is barely there.

The interest is never stored

There's no interest figure held in batzenbox. The app works it out from the history every time. That sounds like a detail, but it's why correcting a week from two years ago works: there's no stored number left to be wrong afterwards.

To the Rappen

Internally it's carried finer than Rappen and only rounded when shown. Over 520 weeks the rounding error would otherwise pile up, and the figure on screen would stop matching anything.

Read on

Start with this week.

batzenbox is the pocket-money notebook for your family: four amounts a week, and the interest comes from the history. Set up your family, put in the first week. That's all it takes.

batzenbox came out of our own family. Who is behind it is in the legal notice.

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