You will have asked yourself more than once how high to hang a picture or how much space to leave between the sofa and the coffee table.
Let’s look together for the mathematical answer to these questions, to obtain a home designed professionally, down to the millimetre.
Curtains and curtains

Curtains and drapes are not just about providing privacy and keeping light out of the room. They also offer the possibility to color the room, liven it up and add a delicate touch.
What to remember:
– 5 cm is the minimum distance between the top of the glass and the balcony. To create the feeling of a taller window, mount the gallery as close to the ceiling as possible.
– 10-25 cm is the distance that must be left between the side edge of the window and the end of the balcony, on each side of the window. The greater the distance, the larger the window will appear.
– Curtains and curtains must be at least twice as wide as the window.
– 0 cm should be the distance between the curtain or drapery and the floor. You can leave 5cm suspended above the floor, but never leave less than a millimeter above the floor.
Images
No room is complete without something hanging on the wall.
– 150 cm is the height at which a picture should be hung, more precisely at an average height, at eye level.
– 5 cm is the space that must be left between 2 or more paintings on the same wall.
– 10-20cm is the approximate space that should exist between the top of the sofa back and the bottom edge of a painting.
Lighting systems
Most rooms require several lighting solutions, each positioned at different levels in the room.
– 170 cm is the ideal height of a floor lamp.
– 150 cm is the minimum height at which it is possible to mount a wall light on the side wall (not on the ceiling).
– 8-15 cm should be the space between a side wall light and the side edge of a mirror or painting.
– 90 cm is the distance at which a switch must be positioned from floor level.
– The distance between the edge of the door and the switch should be 2.5-5 cm.
Furniture
Furniture placement is one of the most confusing and headache-inducing aspects of design. However, hopefully the following figures clear up the confusion:
– 45 cm is the ideal distance between the sofa and the coffee table.
– 25-50 cm is the ideal distance between the edges of the carpet and the walls, in a medium-sized room.
– 90 cm is the ideal distance between the wall and a piece of furniture.
– 80 cm is the average height to which a paneling should rise.
– 30 cm is the ideal depth of a bookcase (40 cm if we have large books).
– 100-110 cm is the distance that must be left between 2 armchairs, to allow the integration of a coffee table in the space between them.
– 60 cm is the distance that should exist between 2 armchairs placed next to each other in a small room.
Colors and prints
When it comes to prints and colors, it’s difficult to establish rules. Here it is very important to follow your instinct, but you can also follow the advice of our guide:
– 60% is the entire space that the main color should cover (usually the walls). for the rest use 2 colors in equal proportions of 15% and a stronger color in a proportion of 10%.
– 3 is the ideal number of prints to use in a room. Mix up the proportions using a large, medium and small print, or try another combination, still limiting yourself to 3 patterns.
All instructions in this guide are starting points only and are not intended to dictate the final outcome or decisions.
It is very important to trust your taste and your practical and artistic sense. In the end, the end result is what you like, what makes you feel comfortable, and what defines you.
Conclusion
Designing a home that feels balanced, comfortable, and visually pleasing is not just about taste — it’s also about precision. The smallest measurements, such as the height of a picture frame or the distance between furniture pieces, can completely transform the way a space looks and feels. Understanding the mathematical relationships within interior design allows you to go beyond guesswork and instead create harmony with intention.
When you know how high to hang a picture or how far to place a coffee table from a sofa, you bring order and proportion into your living space. These seemingly minor adjustments reflect the same principles that professional designers rely on: human scale, functionality, and balance. For instance, aligning artwork at eye level not only ensures visual comfort but also maintains a cohesive flow throughout the room. Similarly, maintaining an appropriate distance between furniture pieces encourages better movement and interaction, making your space more inviting and practical.
Precision in design doesn’t eliminate creativity — it enhances it. By applying mathematical guidelines as a foundation, you gain the freedom to experiment within boundaries that ensure visual stability. Every decision, from wall decor placement to furniture spacing, contributes to the story your home tells about you. The result is an environment that feels naturally put together, where every object has its perfect place and purpose.
In conclusion, designing “to the millimetre” is not about rigidity but about achieving harmony through thoughtful measurement. By combining artistic intuition with mathematical accuracy, you can create interiors that not only look stunning but also feel right. Whether you are redecorating a single room or an entire home, let these proportions guide your design choices — and you’ll discover that beauty often lies in the exactness of the details
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