There is no single perfect lumen number for a wall sconce. It depends on what you expect it to do.
If the sconce is there to add atmosphere in a hallway or living room, 300 to 500 lumens is usually enough. That level creates a soft wash of light across the wall without feeling harsh. It adds depth and shape more than raw brightness.
If the sconce is doing real work, like beside a bathroom mirror or next to a bed for reading, you will want something closer to 500 to 800 lumens. That extra output helps with clarity and reduces eye strain. In a bathroom, two sconces on either side of the mirror often work better than one brighter fixture placed above.
Room size matters too. A small hallway can feel overly bright with high lumen output, while a larger room may need stronger sconces to make any noticeable impact.
It is also worth remembering that shades and materials affect how bright a sconce feels. Frosted glass softens light. An exposed bulb can feel sharper even at lower lumens. Direction plays a role as well. Light aimed upward will feel different than light cast directly outward.
Start by deciding whether the sconce is decorative, functional, or both. Then choose a lumen range that supports that purpose.