Your gallery wall is crooked and everyone is too polite to say so.

tape out the wall's usable width and height on the floor. not roughly — actually measure the wall, actually mark it on the carpet. then arrange the frames inside that outline until it looks right.

the floor beats the wall for this because you can move things a hundred times for free, and because you can look down on it, which is a far more honest view than standing three feet away squinting.

keep the gaps consistent — two to three inches is where most arrangements land — and keep them consistent everywhere, including corners and diagonals. uneven gaps are what the eye reads as "crooked" even when nothing is tilted at all. when it looks right, photograph it from directly above. that photo is your plan.

draw round every frame on kraft paper and cut the shapes out. mark the hanging point on each template — more on that measurement in a moment.

tape the templates up in the arrangement from your photo. then walk away and leave them there for a day.

this feels like an unnecessary step and it's the step that saves you. paper on a wall tells you things the floor can't: that the group sits too high, that it drifts left of the sofa, that it fights with the light switch, that the big one should be a row down. you'll move at least two of them.

this is the actual technique, and it's what separates a gallery wall from a collection of individually level pictures.

pick one horizontal that runs through the arrangement. galleries conventionally set the centre of a hang somewhere around fifty-seven to sixty inches from the floor — roughly average eye level — which is a good starting point, though a wall above a sofa wants the group anchored to the furniture rather than to a number.

then put that line on the wall and relate every frame to it: tops aligned to it, bottoms aligned to it, or the line running through the centres of a row. not to its neighbour. a wall where each frame is levelled against the one beside it accumulates error across the group, and by frame nine you're an inch out and you can see it without being able to say why.

the classic failure: you mark where the top of the frame goes, put the hook there, hang the picture, and it sits an inch and a half lower than planned.

that gap is the drop. hook the wire with a finger and pull it taut toward the top of the frame, the way it'll sit under its own weight, then measure from the taut wire to the top edge. that number — usually an inch to three — is how far below your top-edge mark the hook goes. do it per frame; wires are cut to different lengths and stretch differently.

then hardware, matched to weight and wall: picture hooks into drywall for light frames, proper anchors for heavier ones, masonry fixings for brick, and a stud wherever the layout lets you hit one. on anything wide, use two hooks set well apart instead of one in the middle — a single hook lets the frame rotate, and it will, every time somebody closes a door. bumpers on the bottom corners.