How to Measure a Window Opening

What	Where	How	Unit	Example
Height	Left, centre and right of the opening	Measure three times, write the smallest	mm	1524
Width, top	At the head of the opening	Plaster to plaster	mm	1219
Width, bottom	At the sill	Plaster to plaster; compared with the top it shows whether the wall is true	mm	1219
Count	How many of the same size	Same size on one line, otherwise a new line	pcs	4
Notes	Floor, room, side	Which floor and room, net or no net, old frame present or not	—	3rd floor, bedroom, with net

One opening = one line: height × width (top / bottom) × count. Feet and inches are fine too; we convert to millimetres.

The mistakes we see most

Width written first

Every document of ours is height first, then width. Reversed, a 1219 × 1524 window becomes 1524 × 1219.

Measured at one point only

In older walls the top and bottom widths differ by 10–20 mm. With both written, the cutting list takes the larger and the sash never binds.

Inside the old frame

Measure the bare opening in the wall, not the inside of the old frame — the frame comes out and the new one goes in.

Measured to the grille

With an iron grille, measure plaster to plaster, not the gap inside the grille; note which side the grille is on.

Decimal feet

5'-7" is fine, 5.7 ft is not — 5.7 ft is 5 ft 8.4 in. When in doubt, use millimetres.

No photo

One straight-on photo of the opening saves many questions — sill, beam, pipes and AC units all show.

From measurement to bill: the 1524 × 1219 mm example

Height 1524 mm (5 ft), width 1219 mm (4 ft) top and bottom. For billing each side is rounded up to the next half-foot — here exactly 5 × 4 = 20.00 sft; the measured 19.99 sft is printed beside it.

General model sliding	20.00 × ৳650	৳13,000
Euro model	20.00 × ৳1,055	৳21,100

The same measurement produces the cutting list: O/T 1206, O/B 1206, O/S 1524, S/L 1496, S/T 528, N(H) 1493, N(L) 613 mm; glass 55-7 × 21-5 in, 2 pcs. Fabricators can run their own sizes in the calculator.

What happens after you send the sizes

A hand-written reply within the working day — system, starting rate per square foot and an indicative figure.
Final measurement on site (free in Dhaka) — height at three points, width top and bottom, plaster and sill checked.
The measurement sheet is page one of the quotation, with the drawing and a per-window cutting list for approval.
Final bill on site measurement, with a Mushak-6.3 VAT challan.

KAI sliding window made to the site measurement, Chandrima Udyan — our installation

Mohammadia Housing — openings before glazing, from inside

Questions we are asked

Can I measure in feet and inches?

Yes — write 5'-0" × 4'-0" and we convert to millimetres. Only avoid decimal feet (5.7).

What if the wall is out of true?

Write both widths; the cutting list takes the larger and the frame is packed level. On site we also check the height at three points.

Who works out the cutting sizes?

We do — the clearance from opening to frame (for example O/T = width − 13 mm) is shown in the cutting list; the client never has to calculate it.

Is there a charge when you come to measure?

No. Site measurement within Dhaka is free, whether or not the quotation is taken up.

How should I photograph the opening?

One straight-on and one from the side, so the sill, any beam, pipes or AC unit can be seen. Send them with the sizes on WhatsApp.

Send the sizes, get an indicative figure

Height × width (top / bottom) × count and one photo — a hand-written reply the same day.

WhatsApp the sizes Quick quote on the site Full rate card

Updated 19 September 2026 · rates valid from 16 August 2026

The mistakes we see most

From measurement to bill: the 1524 × 1219 mm example

What happens after you send the sizes

Questions we are asked

Send the sizes, get an indicative figure