Worksheet 01 / measuring

How to measure a door for replacement

Declare whether you are measuring the existing door slab or the frame opening. Take three widths and three heights in millimetres; this sheet reports the minimum, maximum and spread for each axis without choosing an item to order.

Planning worksheet

Outlined door leaf against a blue measuring datumA drawn door slab with three width readings, three height stations and carpenter's setting-out marks.824–826 mm1979–1981 mm
The blue marks reflect the current recorded range after calculation.

Three-point measurement recorder

Record six readings

Formula v1.0.0Researched 2026-09-04

Declared measuring mode

Width readings (mm)

Height readings (mm)

Worked example — default entered values

Measurement record

Width824826 mmSpread: 2 mm
Height19791981 mmSpread: 2 mm

These example readings vary by 2 mm across both axes. The range records variation; it is not a purchasing instruction.

Assumptions register

Worked-example mode: existing door slab. Widths 826, 824 and 825 mm. Heights 1981, 1980 and 1979 mm.

Readings are treated as millimetres. Minima and maxima are taken independently; no allowance, squareness adjustment or product dimension is inferred.

The Marked Door / worked example measurement record
Job/reference: ____________________ · Printed date: ____________________
Canonical record: https://neoporte.com/measure-a-door/ · Formula 1.0.0 · Researched 2026-09-04 · Source: everest-measuring-guide

Before taking the readings

Keep slab and opening measurements separate.

For an existing slab, record the leaf itself at three positions. For a frame opening, record the available opening at three positions and note whether stops, floor finish or other fixed parts affect where the tape was placed.

Do not mix a slab width with an opening width in one set. If the opening is visibly moving, damaged or difficult to define, pause the worksheet and investigate that condition first.

Formula register / 1.0.0

Minimum, maximum and spread

minimum = min(reading 1, reading 2, reading 3)maximum = max(reading 1, reading 2, reading 3)spread = maximum − minimum

Width and height are calculated independently. Missing, non-finite, zero, negative or out-of-bound values return no current result.

Why three readings?

Three positions preserve a simple record of variation instead of hiding it inside one number. The sheet reports what was entered; it does not decide why the values differ.

Read the full methodology and golden vector

Fixed worked example

Existing slab with a 2 mm spread

AxisReadingsMinimumMaximumSpread
Width826, 824, 825 mm824 mm826 mm2 mm
Height1981, 1980, 1979 mm1979 mm1981 mm2 mm

Blank measurement record

Write the positions before the numbers

Job/reference: ____________________   Printed date: ____________________   Mode: slab / frame opening

ReadingPosition noteWidth (mm)Height (mm)
1
2
3

Canonical record: https://neoporte.com/measure-a-door/ · Formula 1.0.0 · Researched 2026-09-04 · Source: everest-measuring-guide

Next check

Keep the method with the measurement.

Review validation and versioning before adapting the record, or open the dated source register.