Rectangle Perimeter Calculator

Calculate a rectangle’s perimeter with precision control, flexible units, and worked steps. Enter length and width in your preferred unit, choose the output unit, and get instant results with validation. Ideal for construction, flooring, packaging, and classroom tasks.

Inputs

Positive number required.
0–10

Result

Enter dimensions and press Calculate Perimeter to see results here.

Quick Tips

  • Perimeter adds all sides: 2 × (L + W).
  • Switch the output unit to compare results across systems.
  • Use higher decimals for small units like mm and inches.
  • Negative or zero values are not allowed.

FAQs

The formula is P = 2 × (Length + Width). Add length and width, then multiply by two.

Yes. Choose the input unit as inches and the output unit as feet. The tool converts automatically.

Intermediate steps use high precision to minimize rounding errors. The final result is rounded to your chosen decimal places.

Use the unit system used on-site. Feet and inches are common in the U.S.; meters or centimeters are standard elsewhere.

Yes. A square is a special case where length equals width. Enter the same value for both fields.

Yes. Use the same parameter names in the URL: ?length=10&width=3&unit=ft&out_unit=ft&precision=2.

Match the unit system and increase the decimal places. Differences usually come from intermediate rounding or unit conversions.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.