Rectangle side length finder

‎Circle circumference calculator

Rectangle Side Length Finder

Enter Perimeter: Enter Known Side (Length or Width): Choose known side type:

A rectangle has 2 equal lengths and 2 equal widths. Given the perimeter and one side, the other side can be found using the formula:

Perimeter (P) = 2 × (Length + Width)
Other side = (P / 2) - known_side

Step 1 → Calculate half perimeter: P ÷ 2

Step 2 → Subtract known side: (P ÷ 2) - known_side

Step 3 → Show result as other side

Step 4 → Draw proportional rectangle graph

Example 1: P = 60 m, known side = 15 m (length)

Step 1 → 60 ÷ 2 = 30
Step 2 → 30 - 15 = 15
Other side = 15 m (width)

Example 2: P = 4000 mm, known side = 1200 mm (width)

Convert mm to meters → P = 4 m, width = 1.2 m
Step 1 → 4 ÷ 2 = 2
Step 2 → 2 - 1.2 = 0.8
Other side = 0.8 m (length)

Example 3: P = 900000000 nm, known side = 400000000 nm (width)

Convert nm to m → P = 0.9 m, width = 0.4 m
Step 1 → 0.9 ÷ 2 = 0.45
Step 2 → 0.45 - 0.4 = 0.05 m
Other side = 0.05 m (length)

For very small units (nm, µm), convert all values to meters before applying formula to maintain accuracy.

The rectangle graph is drawn proportionally:

scaled_side = actual_value × scale_factor

Scale factor adjusts automatically to fit canvas without distortion.

Applications: architecture, robotics paths, game collision detection, PCB layouts, sensor boundaries, land measurements, and physics simulations.