Glass measurement worksheet

Distinguish measured glass from a frame aperture and record a clear, traceable sizing basis.

Choose the correct measurement

Actual pane

Measure actual glass edge to edge. A replacement pane size does not receive a second clearance deduction.

Visible sightline

The opening visible inside beads is not the glass size. Hidden edge cover must be established from the glazing system.

Rebate aperture

The full glazing pocket/aperture needs its specified edge clearances, gaskets, blocks and cover. A building rough opening is a different measurement.

Measure safely. Do not remove beads, handle cracked glass, work at height or expose unsupported panes without a qualified glazier. Use a suitable gauge/records for overall unit thickness and identify the reference face, pane build-up and coatings.

Measurements in millimetres

Sizing basis

Width reading 1 (mm)

Width reading 2 (mm)

Width reading 3 (mm)

Height reading 1 (mm)

Height reading 2 (mm)

Height reading 3 (mm)

Diagonal 1 (mm, optional)

Diagonal 2 (mm, optional)

Derived planning size

Basis supplied

Derived panel dimensions

1000 × 800 mm

Minimum of the three readings; deducted 0 mm total across width and 0 mm total across height. Each edge allowance is explicit; actual-pane measurements have zero deduction.

I have confirmed the measurement boundaries and applicable system clearances.

Measurement worksheet
Basis: Actual glass edges measured; no deduction
Width readings: 1000 / 1000 / 1000 mm
Height readings: 800 / 800 / 800 mm
Diagonal readings: TBC / TBC mm
Derived planning panel: 1000 x 800 mm; total deductions 0 width / 0 height mm.
Variation: 0 mm; diagonal difference: TBC mm.
Measurements not confirmed; do not order from this worksheet.

Replacement unit and coating identification

Record the actual glass/unit size, overall thickness, glazing pocket depth, glass plies, cavity widths, coating/reference faces and any manufacturer markings. Spacer colour alone does not date a unit or establish performance. Overall haze alone does not identify low-E glass: use product records or a suitable coating detector and qualified verification. Do not guess the replacement specification from appearance.

Sources and scope

AGC glazing sizing principles — Manufacturer guidance · 2007; current system instructions govern
AGC coating identification — Version 4.5 · September 2025

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