How this calculator works
Uniform scaling multiplies both rectangle sides by the same positive number. The aspect ratio therefore stays fixed. The perimeter changes by that number, while the area changes by its square. When a target area is supplied, the square root of the area ratio gives the linear factor. This solves proportional resizing rather than independent stretching of the two sides.
Formula
L₂ = kL₁; W₂ = kW₁; P₂ = kP₁; A₂ = k²A₁; k = √(A₂/A₁).
Worked example
A 4 m by 3 m rectangle scaled by 2 becomes 8 m by 6 m. Its area rises from 12 m² to 48 m². To shrink the same original to 3 m², use k = √(3/12) = 0.5, giving 2 m by 1.5 m.
Advertisement
Frequently asked questions
Does twice the area mean twice the width?
No. Uniformly doubling area multiplies both sides by √2, about 1.4142.
Can I set a target width only?
Yes. The width ratio gives the common linear factor, and the length changes proportionally.
Can I use a negative factor?
This page calculates positive dimensions and excludes reflection or orientation. Use a positive factor for enlargement or reduction.