How to Measure Door Architrave Before You Order

A door lining can be perfectly straight and still look unfinished if the architrave is measured incorrectly. Knowing how to measure door architrave before ordering means you can allow for the profile width, mitred corners and cutting waste, rather than finding a supplied length is just short when it matters.

For most internal doors, you will need two vertical lengths and one horizontal head piece. The measurements are straightforward once you decide how the architrave will be fitted, but do not measure only the door leaf. Architrave fits to the door lining or frame face, and its finished size is determined by the lining, the reveal and the joint detail.

What you need before measuring

Use a tape measure, pencil, notepad and a straight edge. A laser measure can be useful on larger projects, but a tape measure remains the best way to check the actual positions where each piece will sit.

Before taking dimensions, confirm the architrave profile and width you intend to use. A 69mm ogee architrave and a 120mm stepped profile will create very different overall dimensions around the same lining. If you are matching existing skirting boards or trims, take a sample or note the precise profile and face width before ordering.

You should also establish whether your door has a standard lining, a rebated frame, a very narrow wall return or uneven plaster. In older properties especially, check each side independently. Door openings are not always square, and relying on one measurement can lead to awkward gaps or excessive scribing later.

How to measure door architrave with mitred corners

The most common arrangement uses two vertical legs with a horizontal head piece, all joined with 45-degree mitres. Start by marking the reveal: this is the small, consistent gap left between the inner edge of the architrave and the edge of the door lining. A 5mm reveal is widely used, although the detail can be adjusted to suit the property or to match existing joinery.

Mark the reveal on both vertical sides of the lining and beneath the head. These pencil lines give you the inside edge of the finished architrave. Measure from the floor to the horizontal reveal line on the left and right sides separately. These are your internal leg heights.

Next, measure the distance between the two vertical reveal lines. This is the internal width of the head piece. Record all three figures clearly, noting which side is which.

With mitred architrave, the cut length is longer than the internal measurement because the outer point of each 45-degree mitre extends by the width of the architrave. For a head piece, add the architrave face width twice to the internal width. For example, if the reveal-to-reveal width is 760mm and the architrave is 70mm wide, the long point of the head piece will be approximately 900mm.

For each vertical leg, add one architrave width to the internal leg height to find the long-point measurement at the top mitre. A leg measuring 2,040mm internally with 70mm architrave will need approximately 2,110mm before allowing for a trimming margin. The bottom is normally cut square to sit on the finished floor or, where fitted first, to be trimmed once floor levels are confirmed.

These calculations apply to a conventional equal-width mitred surround. Always mark the reveal and offer up a short offcut if the profile has an unusual shape, a wide flat section or a prominent moulding that affects how you want the joints to meet.

Measure the fitted floor level, not the subfloor

If carpet, engineered wood, laminate or tile is still to be installed, decide where the architrave will finish. In many projects, it is best for architrave to finish at the final floor height, not disappear behind a thick floor finish. This may mean leaving it slightly long and making the final bottom cut after flooring is complete.

Where a floor covering will run beneath the architrave, measure to the subfloor and allow for the confirmed finished floor build-up. Do not guess this allowance. Underlay, adhesive and levelling compound can change the final level by more than expected.

Measuring for a butt-jointed architrave set

A butt-jointed arrangement has square cuts rather than mitres. It is often chosen for clean, contemporary interiors, particularly with square-edge, chamfered or stepped profiles. The head piece may run between the vertical legs, or it may sit across their tops. The measurement method depends entirely on which detail you choose.

If the head fits between the legs, measure the width between your vertical reveal lines for the head. The vertical legs run from the floor to the underside of the head piece. If the head sits over the legs, measure it across the outside edges of both legs, and stop the legs beneath it.

This is one of the few areas where a simple total length is not enough. Sketch the arrangement, write the intended joint beside each component and calculate every piece separately. It takes two minutes and avoids ordering a set that cannot be cut as planned.

Allow extra length for cutting and defects

Order by the lengths you need to produce, not just the combined measured total. Every piece needs a clean start, a test cut where appropriate and enough spare material to remove a damaged end or correct a slight error. This matters most on tall doorways and wide profiles, where a short offcut may be of little use elsewhere.

As a practical rule, allow at least 100mm to 150mm extra on each individual piece for trimming and mitring. Add more where walls are out of square, floors are uneven or you are fitting architrave for the first time. It is generally better to have one usable offcut than to be unable to complete a doorway because a leg is 20mm short.

For several doors, prepare a cutting list before placing the order. Include the left leg, right leg and head for every opening, then identify the longest required length in each group. Long vertical pieces should normally be supplied and fitted in one length where possible. Joining architrave down a leg is visible and can weaken the finished appearance.

Check clearance around the lining and walls

Architrave needs a flat fixing surface on the lining and wall. Measure the distance from the outside edge of the lining to the nearest return wall, adjoining corner, built-in unit or socket position. A wider profile may look right from the front but run into an obstruction at the side.

Also check how the door opens. Architrave is fitted to the lining face and should not interfere with hinges or the door leaf, but thick trim, tight wall returns and unusual ironmongery can create problems. This is particularly relevant on shallow frames, pocket-door systems and doors close to perpendicular walls.

If you are continuing skirting boards into the doorway, plan the meeting point. Some installations use plinth blocks at the base of the architrave, which can give a more substantial traditional finish and simplify the transition between a tall skirting profile and narrower architrave. Measure the blocks as part of the layout, as they alter the point where the vertical leg begins.

Material choice can affect your fitting plan

Moisture resistant MDF architrave is a practical option for many internal projects. It is consistent, easy to paint and available in a wide choice of profiles, making it well suited to full-house renovations where matching details matter. Primed MDF can also reduce preparation time before decorating.

Oak and pine architrave bring natural grain and are often selected where a stained, oiled or clear-finished timber appearance is required. Timber can have natural variation, so inspect lengths and position the best faces where they will be most visible. In humid or recently plastered rooms, allow materials to acclimatise before fitting and avoid forcing a bowed length tight against an uneven wall.

Whichever material you choose, use a sharp saw and make test cuts from an offcut. Mitres that look correct on a tape measure can open up if the lining is not square. A small adjustment to the saw angle, followed by careful sanding and filling where suitable, produces a cleaner result than trying to pull a poor joint together with fixings.

A final check before you place the order

Read through your cutting list one last time and check that every measurement relates to the reveal line or intended joint, rather than the door leaf. Confirm the profile width, required stock lengths, finished floor position and whether you need matching skirting, plinth blocks or other trim.

For projects with multiple rooms, ordering a sample first can be worthwhile. It lets you judge the profile against the door style, wall colour and skirting before committing to full lengths. My Skirting Boards manufactures architrave in-house in a range of MDF, oak and pine profiles, so selecting coordinated finishing timber does not have to mean compromising on the measurements you need.

A careful measure, a clear cutting list and a modest allowance for fitting will make the installation calmer from the first mitre to the final coat of paint.