Pets calculator
What Cat Door Size Do I Need?
Calculate minimum cat-door opening using widest body width, shoulder height, and opening width allowance.
Enter your measurements
Use this minimum-size calculation when you need to answer “what cat door size do i need?” Enter widest body width, shoulder height, and opening width allowance and the tool returns minimum cat-door opening using the rule defined for this exact use case.
- Widest body width — Required
- Shoulder height — Required
- Opening width allowance — Required
- Step-over height — Required
Minimum cat-door opening
Enter the measurements above to calculate minimum cat-door opening.
How the calculation works
This calculator applies minOpeningWidth=catBodyWidth+widthAllowance; minOpeningHeight=max(0,catShoulderHeight-stepOverHeight). The resulting value or pass/fail state is reported as minimum cat-door opening.
Worked example
Example: Widest body width = 60 cm; Shoulder height = 30 cm; Opening width allowance = 5 cm; Step-over height = 8 cm. Result: Min Opening Height = 22 cm; Min Opening Width = 65 cm.
Before you decide
Use measured dimensions rather than nominal labels. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what cat door size do i need, the limiting result on this page is minimum cat-door opening.
Direct measurement/geometry calculation. No external reference is required for the arithmetic itself; the result is derived only from the user-entered measurements and the formula stored in calculationLogicJson.
Frequently asked questions
How does the Cat Door Size | Size Guide calculator work?
It uses minOpeningWidth=catBodyWidth+widthAllowance; minOpeningHeight=max(0,catShoulderHeight-stepOverHeight). The result is minimum cat-door opening.
Which measurements or specifications do I need?
Use these inputs: Widest body width, Shoulder height, Opening width allowance, Step-over height. Measure or copy the values from the exact product/specification rather than guessing.
Is the result a guarantee that the product will fit or be suitable?
No. The calculator answers the stated minimum cat-door opening question. Manufacturer instructions, safety rules, certification, installation tolerances or brand-specific size charts can impose additional requirements.