How to Design Door and Window Sizes Correctly?

Doors and windows are among the most important features of a home, directly affecting natural light, ventilation, and overall comfort. But do you really know how to accurately design their dimensions? Today, from a craftsman’s perspective, I’ll break it all down for you—no fluff, just straight talk.

About Window Sills: Are Yours Installed Correctly?
Generally, the height of a residential window sill should not be lower than 0.9 meters. If it’s below 0.8 meters, protective measures must be added—no compromises here, especially if you have kids at home.
In public buildings, sill heights usually range from 1 meter to 1.8 meters. If the window opens toward a public passage, the bottom of the window should be at least 2 meters from the floor—this prevents accidents and ensures privacy.

💡 Did you know?
Why are some old houses built with very low sills?
In the past, low sills were designed for better views and more light, but nowadays, safety standards require higher sills.

Window Height: Bigger Isn’t Always Better
In most homes, the height of a window is usually around 1.5 meters. With a 0.9-meter sill, the top of the window sits about 2.4 meters from the floor—a comfortable and proportional look.
If you want to go higher—like those trendy large-pane windows—reinforcement is a must. Otherwise, over time, they may warp or develop drafts. We typically recommend adding a horizontal beam or reinforced framing.
Windows exceeding 7.2 meters are more common in commercial buildings and require specialized structural design.

🤔 Food for thought:
If you were to install windows on your balcony, would you choose one large fixed pane or several openable sections?
—Many people choose big windows for the view, but don’t overlook wind resistance and support!

Window Width Follows a Pattern
Standard window widths start at 0.6 meters and increase in 300mm increments: 0.9m, 1.2m, 1.5m, etc.
If you’re planning a long continuous window, be sure to add vertical mullions in between. Otherwise, you may end up with operating problems and sagging hardware.

Door Height: It’s Not Just About Size
For standard passage doors, the height should be between 2 meters and 2.4 meters. Anything taller can feel hollow and may lead to structural warping.
Some people add a transom window above the door for more light—that’s fine, but keep its height around 0.4 meters.
For utility access or mechanical rooms, doors can be lower—around 1.5 meters is sufficient—with a threshold at the bottom to block sightlines.

Door Width Should Match Its Purpose

• Main entrance door: 0.9–1 m
• Bedroom door: 0.8–0.9 m
• Kitchen door: around 0.8 m
• Bathroom door: 0.7–0.8 m

Most people nowadays prefer the wider end of these ranges—after all, sofas and cabinets need to get through the door.
For public spaces or double doors, common widths are 1.2–1.8 meters. Anything wider may require multi-panel designs, with each panel ideally between 0.6–1 meter.

📌 A little tip from the pros:
Many people focus only on style during renovation and overlook precision in dimensions. The result? Doors that don’t fit, windows that won’t open…
Remember: dimensions are the skeleton, materials are the flesh, hardware is the joints—every part matters.

✅ Quick Self-Check:

• Is your bathroom door wide enough for a washing machine?
• Should you opt for low-e glass? —Best for west-facing rooms, protects against heat and UV.
• inward or outward opening? —Outward saves space, but must be securely installed.

Doors and windows are the “eyes of your home.” Getting their dimensions right isn’t just a numbers game—it affects safety, function, and everyday experience. If you’re selecting doors and windows, I hope this guide helps you avoid common pitfalls.