How big should mirror be over fireplace?

The Size of Your Mantel Should Be Considered When Purchasing a MirrorKuo advises that no matter what shape of mirror you choose, the width should be at least two-thirds of the fireplace mantel when hung above the fireplace.

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What shape mirror is best over fireplace?

Style-wise, a round mirror hung above a fireplace looks great. The round shape breaks up the straight lines of the mantle, hearth, and chimney breast.

Is it OK to hang a mirror over a fireplace?

You can hang a mirror over stone fireplaces (or on a brick wall above fireplaces) by drilling holes into the brick and inserting plastic or metal anchors into the holes.