Garden & Outdoor calculator
What Pergola Size Do I Need?
Use your measurements for area to cover width, area to cover length, and post inset from roof edge to find pergola roof, post spacing and site envelope.
Enter your measurements
Rather than guessing what pergola size do i need, enter area to cover width, area to cover length, and post inset from roof edge. The result is pergola roof, post spacing and site envelope, calculated specifically for this product or space decision.
- Area to cover width — Required
- Area to cover length — Required
- Post inset from roof edge — Required
- Boundary clearance — Required
Pergola roof, post spacing and site envelope
Enter the measurements above to calculate pergola roof, post spacing and site envelope.
How the calculation works
For this tool, the calculation is roofWidth=targetZoneWidth; roofLength=targetZoneLength; postCentreWidth=max(0,roofWidth-2×postInset); postCentreLength=max(0,roofLength-2×postInset); minimumSiteWidth=roofWidth+2×clearanceFromBoundaries; minimumSiteLength=roofLength+2×clearanceFromBoundaries. That produces pergola roof, post spacing and site envelope without borrowing assumptions from unrelated calculators.
Worked example
Example: Area to cover width = 60 cm; Area to cover length = 400 cm; Post inset from roof edge = 5 cm; Boundary clearance = 5 cm. Result: Minimum Site Length = 410 cm; Minimum Site Width = 70 cm; Post Centre Length = 390 cm; Post Centre Width = 50 cm.
Before you decide
The result is only as accurate as the measurements entered. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what pergola size do i need, the limiting result on this page is pergola roof, post spacing and site envelope.
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 Pergola Size | Size Guide calculator work?
It uses roofWidth=targetZoneWidth; roofLength=targetZoneLength; postCentreWidth=max(0,roofWidth-2×postInset); postCentreLength=max(0,roofLength-2×postInset); minimumSiteWidth=roofWidth+2×clearanceFromBoundaries; minimumSiteLength=roofLength+2×clearanceFromBoundaries. The result is pergola roof, post spacing and site envelope.
Which measurements or specifications do I need?
Use these inputs: Area to cover width, Area to cover length, Post inset from roof edge, Boundary clearance. 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 pergola roof, post spacing and site envelope question. Manufacturer instructions, safety rules, certification, installation tolerances or brand-specific size charts can impose additional requirements.