Use millimetres (mm) Do not mix centimetres and inches on the same list. One wrong unit ruins a whole fabrication run.

1. Decide what you are measuring

Finished opening — the clear hole in the wall after plaster / tiling where the new frame will sit. Prefer this for replacements when the old frame will be removed.

Existing frame (overall) — outside of the current aluminium/wood frame. Useful only if the new unit must drop into the same footprint without disturbing finishes.

Tell us which one you measured when you send sizes.

2. Width — three readings

Measure left-to-right at the top, middle and bottom of the opening. Write all three. Use the smallest width for quoting.

WIDTH ×3 — use smallest HEIGHT ×3

3. Height — three readings

Measure top-to-bottom at the left, centre and right. Again, record the smallest height. Floors and lintels are rarely perfectly level.

4. Note extras

  • Does the door swing in or out? Left or right hand?
  • Is there a mosquito mesh track?
  • Are tiles or skirting still to be installed? (That changes the finished opening.)
  • Any pipes, AC units or burglar bars in the way?

5. Photos that help

On WhatsApp, send: (1) the full opening from outside, (2) from inside, (3) a close-up of the existing frame edge if replacing. A tape in the photo is even better.

Enter sizes in the quote builder Glass & finishes guide