How to measure your windows and doors for a quote

You do not need to be a fitter to get a useful estimate. Two careful measurements, a few photos and a note of where each window is will let us price the job. Every size is checked again at a free survey before anything is made, so a few millimetres out at this stage is fine.

Before you start

• Use a metal tape. Fabric tapes stretch.
• Work in millimetres. 1.2 m is 1200 mm.
• Number each window and door on a rough sketch of the house (W1, W2 and so on). It saves confusion later.
• Measure the frame itself, not plastic trims or silicone around it.

Measure from outside where you can do it safely. Upstairs, measure the visible frame from inside and tell us that is what you did. Do not lean out of windows or climb a ladder for a figure. We measure everything at survey.

1. Measure the width

Measure the existing frame from outside edge to outside edge at the top, middle and bottom. Write down the smallest of the three figures.

If you can see the brickwork either side, measure brick to brick as well. That is the structural opening, and it tells us how much room there is for the new frame.

2. Measure the height

Measure from the top of the frame down to where the frame meets the cill, on the left, centre and right. Again, keep the smallest figure. Do not include the cill itself.

Note what the cill is made of. A uPVC or timber cill usually comes out with the old window. A stone or concrete cill normally stays, and the new frame sits on it.

3. Doors and patio doors

Measure the outer frame width at the top, middle and bottom. Measure the height from the top of the frame to the threshold on both sides. Keep the smallest figures. Note any step down outside, any side panels, and any glazed panel above the door (a top light).

4. Note how each one opens

• Which panes open, and which side they are hinged on, viewed from outside
• Any change you want to the layout
• Whether the window is in a bedroom or other habitable room upstairs. One opener may need to meet fire-escape sizes.
• Whether the old windows have trickle vents (thin slots along the top of the frame). If they do, the new ones must have them too.

Our Building Regulations guide explains the escape, ventilation and safety glass rules.

5. Take photos

• Each window or door from outside, square on, with the whole frame in shot
• The same window from inside, showing the window board, blinds and any radiator underneath
• For doors, a close-up of the lock edge and the threshold
• For bays, one photo from a few steps back so we can see the angles

6. Enter your sizes in the quote builder

Our online quote builder shows a drawing of each window or door. Type the width and height straight onto the drawing, then choose the product, opening side, glass, trickle vents and colour. The drawing is viewed from outside and redraws as you type. The dashed lines meet at the hinge side, so you can check the opening is right before you add it to your list.

Repeat for each window and door. When the list is complete, send it to us on WhatsApp as one numbered schedule, with the total area worked out for you. Attach your photos in the same chat. Not sure of a size? Leave it blank and add a note.

Common mistakes

• Measuring in centimetres or inches
• Including the cill in the height
• Measuring one side only. Old openings are rarely square.
• Rounding up. If in doubt, round down to the nearest 5 mm.

Why we still survey

Openings are rarely square. Lintels and bays may carry load. The rules on escape, ventilation and safety glass all affect the final specification. A short survey at your home lets us confirm every size and detail before anything is made. The fixed price is then confirmed on your written quote.