Add opening reveals separately from the wall face.
Does subtracting a window or door face also account for its exposed returns?
Use the matching calculator
Use this decision sequence
- Calculate the flat wall face with its chosen opening deductions.
- Measure the exposed return depth separately from wall-face dimensions.
- Select the jamb, head and sill faces actually receiving the same finish.
- Add those return surfaces once instead of treating them as another opening deduction.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Opening face | May be deducted from the flat wall. |
| Reveal faces | Are additional surfaces perpendicular to that wall. |
| Selected sill | Is included only when it receives this finish. |
Worked comparison
A 1 m by 2 m opening with 0.2 m exposed depth has 0.8 m² across its two vertical jambs. The horizontal head adds 0.2 m², for 1 m² of reveals without a sill. The 2 m² opening face and the 1 m² return surface are different quantities and should not be substituted for each other.
Check before using the estimate
Flat rectangular returns only. This does not design the opening, lintel, window assembly or a fire-rated detail. 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.