An instrument used in mathematics and engineering to measure distances or to draw perfectly straight lines.

A ruler is usually relatively short. See measuring stick for long rulers.

See also

• Caliper
• Compass (instrument)
• Measuring stick
• Protractor
• Set square
• Steel square
• Straightedge
• T-square
• Tape measure
• Holding ruler

The following tags implicate this tag: holding_ruler (learn more).

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