Full-motion mounts: arm length and swivel
People buy a full-motion mount expecting the TV to turn 90 degrees, hang it, and discover it only manages 20. The limit is almost always the same: the edge of the TV hits the wall before the arm runs out of swivel.
The geometry in one sentence
To swivel a TV, the arm has to push it far enough from the wall that the screen's edge can swing past without touching.
A quick rule
For a 90-degree turn, the arm must extend to at least half the TV's width. For 45 degrees — which is what most rooms need — about a third of the width is enough.
| Screen | Approx. width | Extension for ~45° | Extension for ~90° |
|---|---|---|---|
| 43″ | 37″ | 13″ | 19″ |
| 55″ | 48″ | 17″ | 24″ |
| 65″ | 57″ | 20″ | 29″ |
| 75″ | 65″ | 23″ | 33″ |
| 85″ | 74″ | 26″ | 37″ |
Most mid-priced arms extend 16 to 24 inches. That's why a 43-inch TV on a typical arm can turn fully sideways and a 75-inch on the same arm cannot.
Off-centre mounting changes the numbers
If the wall plate sits to one side of the TV's centre, the TV can turn further one way and less the other. That's sometimes useful: in a corner, mount the plate nearer the corner and the screen swings out to face the room.
Single arm or dual arm?
- Single-arm mounts have more sideways reach and suit lighter TVs.
- Dual-arm mounts are stiffer and carry heavy screens, but each arm limits the other, so maximum swivel is often lower than the box suggests for big TVs.
Collapsed depth
The more arm there is, the further the TV sits from the wall when pushed back — commonly 2.5 to 4 inches, against about 1 inch for a fixed bracket. If a flush look matters, check the "profile" figure.
Sag and levelling
A long arm with a heavy TV droops slightly at full extension. Better mounts have a tilt-tension adjustment and a post-install level screw to correct it. Staying well under the weight rating reduces sag.
What the wall has to do
Extended, the arm acts as a lever on the top bolts. This is the mount type where stud anchoring isn't negotiable, and where two studs beat one for anything large. Background in is my wall strong enough.
Cables
Leave enough slack for full extension and clip the cables along the arm, or the first swivel will pull the HDMI plug out of its socket.
Do you actually need 90 degrees?
Usually not. Stand where you'll watch from the kitchen or the dining table and estimate the angle — 30 to 45 degrees covers most open-plan rooms.
Our full-motion option is $89 including a bracket chosen for your screen size; tell us in the notes if you need a specific angle.