The short answer: ask how high to hang shelves and you will get four different numbers, and all of them are correct. On a blank wall, the answer is measured from the floor: around 54 to 60 inches to the middle of the shelf, which puts it at eye level. Above furniture, the answer is measured from the furniture instead, so a shelf above a sofa sits 10 to 12 inches above the backrest and one above a desk sits 22 to 24 inches above the desktop. Those two baselines are the whole reason the internet appears to contradict itself. Work out which one applies to your wall, then check that the anchors you are using can actually hold what you plan to put on it, because that is the number nobody publishes at all.
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