Distinguish a rectangular liner blank from inside box surface area.
Why is an uncut box liner rectangle larger than the surfaces it covers?
Use the matching calculator
Use this decision sequence
- Use the inside base dimensions and specified covered depth.
- Add the supplied edge allowance beyond both opposing walls.
- Calculate the complete uncut rectangle before checking stock fit.
- Keep corner surplus and any installation method outside the surface-area comparison.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Inside surface | Counts the base and four vertical faces. |
| Rectangular blank | Also retains material around the corners. |
| Waterproof performance | Is not established by either area. |
Worked comparison
A 2 m by 1 m inside base with 0.5 m covered depth and 0.1 m edge allowance needs a 3.2 m by 2.2 m uncut blank, or 7.04 m². The base and four wall faces total only 5 m². The difference includes corner surplus and edge allowance, so ordering by inside surface area alone would not describe that rectangle.
Check before using the estimate
No folding, joining, drainage, waterproofing or material-compatibility method is supplied. The example values are illustrative arithmetic inputs. Replace them with your measured plan, selected product information and actual quote where relevant.
All dimensions, product properties, prices and specifications in this example are illustrative arithmetic inputs. Use the values from your measured plan, selected product data sheet and supplier quote. This guide does not choose construction specifications or certify safety.
Calculation and scope checked 2026-10-04. Methods and scope.