The 60/30/10 rule

Every room that works distributes its colours across three very unequal weights. 60% for the dominant, 30% for the secondary, 10% for the accent. That is all.

The rule has circulated among interior designers for over fifty years. It rests on a simple observation: the eye needs a large calm zone to appreciate touches of more vivid colour. Without this hierarchy, the gaze has nowhere to settle, and the room seems restless even if each shade is beautiful on its own.

The key word here is surface. Not feeling, not intention. The colour that occupies the most visible square metres is your dominant, whether you intended it or not. That is what makes the rule so difficult to sidestep.

The method comes down to three steps, in this order.

1. Identify your dominant before any other choice. Walk around the room and look at the large surfaces: walls, floor, ceiling, large curtains. The most present colour is your dominant. Example: off-white walls with light oak flooring give you a warm neutral dominant. This is an observation, not a decision to be made.

2. Choose the secondary based on the dominant. It is carried by the major furniture pieces: sofa, armchairs, main rug, headboard. The rule is mechanical. If your dominant is warm (beige, linen, pale terracotta), your secondary must be too. Sage green, teal, terracotta work. Glacier blue or cold grey will clash. Conversely, on a cool dominant (pure white, pearl grey), go with cool secondaries: deep blue, seafoam, anthracite.

3. Place the accent in at least three spots. It is the room's signature, the slightly bold touch. A mustard cushion, a vase in the same shade, a framed artwork. If you use it in only one place, it looks accidental. If you use it in more than five, it is no longer an accent, it becomes a third colour taking up too much space.

Interior designers allow themselves variations, but always intentional ones.

Pierre Yovanovitch often works in 70/20/10 in his most stripped-back interiors. The dominant, almost always an off-white or stone grey, takes up even more space to showcase the volumes and the furniture pieces he designs. The secondary becomes more discreet, the accent holds its position.

Studio KO sometimes shifts toward 50/40/10 when two main colours need to dialogue almost equally, typically in their Moroccan projects where a deep ochre and an intense blue coexist without clear hierarchy. It is delicate to hold, the risk of falling into flag effect is real.

What never changes is the 10%. As soon as the accent exceeds 15% of the room, it ceases to be a focal point and becomes a true third colour that dilutes the whole. The rule can stretch upward (70/20/10), never downward.