Since 1926, Poul Henningsen’s three-shade system has defined the way we think about light. It was created to solve a simple but pressing problem: how to enjoy bright, functional light without the harsh glare of a bare bulb.
Every PH lamp is defined by a simple two-part number, such as PH 4/3 or PH 4/4.
The first number refers to the diameter of the top shade, measured in decimetres — so “4” means 40 cm. The second number shows the set of lower shades it is paired with.
There are two types of proportion. A “whole number” lamp such as PH 3/3 or PH 4/4 uses a full set of three shades in the same scale. Other models, such as PH 3/2 or PH 4/3, combine the top shade from one size with the lower shades from a smaller model. This creates a lighter expression and directs more light downwards, making these versions especially suited for tasks such as table lighting.
This early drawing shows the variations of the three-shade lamp, demonstrating the precision and thoughts behind each model.
At the heart of the PH system lies the logarithmic spiral, a natural curve also found in seashells and plants. By shaping the shades according to this geometry, Poul Henningsen created a lamp that distributes light in gentle layers, free from harsh contrasts.
The top shade takes care of the brightest light, the middle shade redirects and softens it, and the bottom shade shields the eyes from glare. Together, they create a warm, balanced illumination that feels as natural as daylight and as inviting as candlelight.
Before the PH system, lighting typically meant discomfort. Bare bulbs cast harsh, uncontrolled light that strains the eyes. Simple shades offer softer illumination, but often still leave glaring escape paths.
The PH three-shade system softens and balances light, delivering layered illumination that feels both comfortable and elegant.
