Ruler Calculator
Ruler Fraction Reader works out Converted value and Unrounded result from Value, From unit and Ruler divisions per inch. The default figures on this page give converted value of 2.6875; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- 1 in = 1 in
- 2.7 x 1 = 2.7 in
- 2.7 in x 16 = 43.2 divisions, nearest whole division 43
- 43/16 in = 2 11/16 in
Its 12 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
2 sources
What the Ruler Fraction Reader calculates
Converts a quantity between any two units of the same physical family using exact SI-derived factors.
How to use this Ruler Fraction Reader
Enter Value, From unit, Ruler divisions per inch and Significant figures. Converted value updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Converted value, Unrounded result and Conversion.
The method follows NIST Special Publication 811, Guide for the Use of the International System of Units and BIPM, The International System of Units (SI Brochure).
What you can compare
Change one input at a time to see how it affects Converted value, Unrounded result and Conversion. The inputs you can vary are Value, From unit, Ruler divisions per inch and Significant figures.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I get a ruler on my screen?
Converts a quantity between any two units of the same physical family using exact SI-derived factors. Open “How this is worked out” beside the result to see each step for your own figures.
Can I use my phone as a ruler?
Converts a quantity between any two units of the same physical family using exact SI-derived factors. On the figures this page opens with — value 1 — the converted value is 2.6875. Put your own figures in their place and the working updates beside the result.
How to calculate a ruler?
It needs Value, From unit, Ruler divisions per inch and Significant figures. Nothing else is required, and the figures stay in your browser.
What information do I need for the Ruler Fraction Reader?
You need Value, From unit, Ruler divisions per inch and Significant figures. The page opens with default figures that give converted value of 2.6875, so you can see the scale before entering your own.
What does this Ruler Fraction Reader show?
It shows Converted value, Unrounded result, Conversion, Reading, Multiply by and Reverse conversion, with the working and any warnings for your entries.
Can I check how the Ruler Fraction Reader result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.