Build it on the floor first
Lay the frames out on the floor in the shape of the wall before a single nail goes in. Rearranging on the floor costs nothing. Rearranging on plaster costs you a wall.
Find the center line
Hang so the middle of the whole arrangement lands around 57 to 60 inches from the floor. That is roughly standing eye level and it is the convention galleries use. The center of the group is what matters, not the center of any one frame.
Keep the gaps equal and tight
Two to three inches between frames reads as one composition. Wider than about four inches and the eye stops grouping them, so you get several small pictures instead of one large statement.
Above furniture
When a gallery wall sits over a sofa or console, ignore the eye-level rule and work from the furniture. Start six to eight inches above the back of the piece, and keep the arrangement narrower than the furniture below it so it reads as anchored.
Two decisions that hold it together
- Pick one constant. Same frame color, or same mat width, or same subject. One repeated element lets everything else vary.
- Use an odd number in a row and an even number in a grid. A grid wants to be square; a row wants a middle.
When to stop
The arrangement is finished when the outline is a recognizable shape — a rectangle, a column, a stepped line. If you cannot describe the shape, another frame will not fix it.