Circular Slide Ruler

Matteo Bertini

About this app

Once all the pilots had a rule of this kind on the clock, knowing how to do multiplication and division quickly could save your life.

Today planes rely on very different technologies but the rule is still useful whenever you want to do operations without having to type. Just line up the two numbers to get quickly tabs on all their multiples.

Very useful for travel, just set the exchange rate, for example, if 1 U.S. Dollar is worth 0.75 Euros, how many U.S. Dollars costs a 40 Euros backpack? Just look at the Ruler to see it costs about 53 U.S. Dollars, without doing math!

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Ratings and reviews

It's clear and easy to use, but the scale divisions are horribly inadequate. If you line up the 10 and the 20 this becomes blindingly obvious. Sort this out and I'd give it 5 stars, but as it is it's practically useless, unless you've got interpolative superpowers.

This is very intuitive, and easy to use. The lack of complex graphics means that the screen motion is smooth with no lag. This goes into my regular set of favourite slide rules which I use often. There is space on the rule for further graduations among the early numbers; line length will be sufficient to highlight them as appropriate. With sufficient useful graduations visible, this will make a VERY high resolution slide rule when used on a large tablet. Dragging outside the circle is superb!

Such a great program! Thanks! Couple of features I'm missing: Setting ratio numerically in an input field.List of shortcut user-defined ratios, for example, miles to km, usd to pesos. More dense scale between 10 and 15. Don't mind sharing the source code?

What's new

What's new:

- Orientation is now fixed
- Optional dark theme
- Use better the screen space (slightly bigger radius)
- 10 is painted in swapped colors for better identification

Thanks you all for the suggestions!