Enter the shelf. We compute day-one sag and long-term sag (wood creeps — shelves sag about 50% more over the years) and rate it against the 0.02 in/ft line where sag becomes visible.
Unsupported length. Fractions OK: 35 1/2
Free and unlimited. Checking a whole project at once — every shelf and panel, saved and printable — is the $39 Design-Checked Project Kit.