Before ordering a window, you need to measure correctly. This guide covers taking a measurement at home yourself. For an accurate order, we recommend booking our specialist (the service is free).

What you need

• A 3-metre metal tape measure
• Notepad and pencil
• A chair or step ladder (for high windows)

Steps

1. Measure without removing the old window first. While the old frame is in place you cannot see the true opening size — do not measure from the old frame's edge.
2. Measure the width at three points: top, middle, and bottom. Record the smallest value.
3. Measure the height at three points too: left, middle, right. Record the smallest value.
4. Check the diagonals. The diagonals should be equal (a difference of up to 5 mm is acceptable). If the gap is bigger, the opening is not square — coordinate with the installer.
5. Subtract 1 cm from each side for the installation gap. Example: smallest reading 1500×1400 mm — the order spec becomes 1480×1380 mm.
6. Measure the opening depth (inside to outside). This figure determines profile choice (Termo 80 = 80 mm, Termo 98 = 98 mm).
7. Sketch the layout — mark sections (opening / fixed), and the direction each sash swings.
8. Book our specialist for accuracy. Our team member arrives with a laser distance meter, verifies the measurements, and prepares a technical card. Free of charge, no obligation.

Common mistakes

• Measuring from the old frame's edge (confusing it with the opening size)
• Forgetting the installation gap (the 1 cm rule)
• Skipping the diagonal check
• Not measuring profile depth (the new window won't fit the old space)

Next step

Once you have your measurements, request a quote via /contacts. We respond with a costing within 24 hours.