These tables contain comparative shelf sag measurements for 16″ deep shelves ranging in width from 30″ to 54″. Six types of shelving materials (all 3/4″ thick), three shelf loads (20, 30, 40 pounds per linear foot), and several shelf support techniques are represented. Sag measurements are to the nearest hundredth of an inch. As a general guideline, shelf sag should be 0.10″ or less.
8″ shelves | 12″ shelves | 16″ shelves | About these sag measurements
Shelf Width: 30″ (Optimal sag: 0.05″ or less, excessive: 0.13″+ )
| End Support | Front Support | Rear Support | Lbs per ft | Lbs total | MDF | Plywood | Pine | Poplar | Cherry | Oak |
| Float | No | No | 20 | 50 | n/a | .03 | .01 | .01 | .02 | .02 |
| Float | No | No | 30 | 75 | n/a | .04 | .02 | .02 | .04 | .02 |
| Float | No | No | 40 | 100 | n/a | .05 | .03 | .03 | .05 | .03 |
| Fixed | No | No | 20 | 50 | n/a | .02 | .01 | .01 | .01 | .01 |
| Fixed | No | No | 30 | 75 | n/a | .03 | .02 | .02 | .03 | .02 |
| Fixed | No | No | 40 | 100 | n/a | .04 | .02 | .03 | .03 | .03 |
| Fixed | Yes | No | 20 | 50 | n/a | .02 | .01 | .01 | .01 | .01 |
| Fixed | Yes | No | 30 | 75 | n/a | .03 | .01 | .01 | .02 | .02 |
| Fixed | Yes | No | 40 | 100 | n/a | .03 | .02 | .02 | .02 | .02 |
| Fixed | No | Yes | 20 | 50 | n/a | .02 | .02 | .01 | .02 | .01 |
| Fixed | No | Yes | 30 | 75 | n/a | .04 | .02 | .03 | .03 | .02 |
| Fixed | No | Yes | 40 | 100 | n/a | .04 | .03 | .04 | .04 | .02 |
| Fixed | Yes | Yes | 20 | 50 | n/a | .01 | .01 | .00 | .01 | .01 |
| Fixed | Yes | Yes | 30 | 75 | n/a | .02 | .02 | .01 | .01 | .01 |
| Fixed | Yes | Yes | 40 | 100 | n/a | .02 | .02 | .01 | .02 | .01 |
Shelf Width: 36″ (Optimal sag: 0.06″ or less, excessive: 0.18″+)
| End Support | Front Support | Rear Support | Lbs per ft | Lbs total | MDF | Plywood | Pine | Poplar | Cherry | Oak |
| Float | No | No | 20 | 60 | n/a | .05 | .03 | .02 | .04 | .03 |
| Float | No | No | 30 | 90 | n/a | .08 | .05 | .05 | .06 | .04 |
| Float | No | No | 40 | 120 | n/a | .10 | .07 | .06 | .08 | .05 |
| Fixed | No | No | 20 | 60 | n/a | .05 | .03 | .02 | .03 | .03 |
| Fixed | No | No | 30 | 90 | n/a | .06 | .05 | .04 | .05 | .04 |
| Fixed | No | No | 40 | 120 | n/a | .08 | .06 | .06 | .07 | .05 |
| Fixed | Yes | No | 20 | 60 | n/a | .03 | .01 | .01 | .01 | .01 |
| Fixed | Yes | No | 30 | 90 | n/a | .04 | .02 | .02 | .03 | .02 |
| Fixed | Yes | No | 40 | 120 | n/a | .06 | .03 | .02 | .03 | .03 |
| Fixed | No | Yes | 20 | 60 | n/a | .04 | .03 | .02 | .03 | .01 |
| Fixed | No | Yes | 30 | 90 | n/a | .06 | .04 | .03 | .04 | .03 |
| Fixed | No | Yes | 40 | 120 | n/a | .07 | .05 | .05 | .05 | .04 |
| Fixed | Yes | Yes | 20 | 60 | n/a | .03 | .01 | .01 | .01 | .01 |
| Fixed | Yes | Yes | 30 | 90 | n/a | .04 | .02 | .02 | .01 | .02 |
| Fixed | Yes | Yes | 40 | 120 | n/a | .05 | .03 | .03 | .02 | .03 |
Shelf Width: 42″ (Optimal sag: 0.07″ or less, excessive 0.21″+)
| End Support | Front Support | Rear Support | Lbs per ft | Lbs total | MDF | Plywood | Pine | Poplar | Cherry | Oak |
| Float | No | No | 20 | 70 | n/a | .12 | .08 | .06 | .08 | .04 |
| Float | No | No | 30 | 105 | n/a | .14 | .12 | .09 | .11 | .06 |
| Float | No | No | 40 | 140 | n/a | .19 | .16 | .12 | .15 | .09 |
| Fixed | No | No | 20 | 70 | n/a | .08 | .06 | .04 | .05 | .04 |
| Fixed | No | No | 30 | 105 | n/a | .12 | .08 | .07 | .09 | .07 |
| Fixed | No | No | 40 | 140 | n/a | .16 | .11 | .10 | .11 | .09 |
| Fixed | Yes | No | 20 | 70 | n/a | .04 | .02 | .03 | .02 | .01 |
| Fixed | Yes | No | 30 | 105 | n/a | .06 | .04 | .04 | .03 | .02 |
| Fixed | Yes | No | 40 | 140 | n/a | .09 | .05 | .05 | .05 | .04 |
| Fixed | No | Yes | 20 | 70 | n/a | .04 | .05 | .03 | .04 | .03 |
| Fixed | No | Yes | 30 | 105 | n/a | .08 | .07 | .05 | .06 | .06 |
| Fixed | No | Yes | 40 | 140 | n/a | .12 | .09 | .08 | .09 | .07 |
| Fixed | Yes | Yes | 20 | 70 | n/a | .04 | .02 | .01 | .01 | .01 |
| Fixed | Yes | Yes | 30 | 105 | n/a | .06 | .03 | .02 | .01 | .02 |
| Fixed | Yes | Yes | 40 | 140 | n/a | .08 | .04 | .03 | .03 | .03 |
Shelf Width: 48″ (Optimal sag: 0.08″ or less, excessive: 0.24″+)
| End Support | Front Support | Rear Support | Lbs per ft | Lbs total | MDF | Plywood | Pine | Poplar | Cherry | Oak |
| Float | No | No | 20 | 80 | n/a | .17 | .17 | .13 | .12 | .10 |
| Float | No | No | 30 | 120 | n/a | .25 | .24 | .16 | .18 | .13 |
| Float | No | No | 40 | 160 | n/a | .33 | .32 | .23 | .24 | .18 |
| Fixed | No | No | 20 | 80 | n/a | .13 | .11 | .10 | .11 | .07 |
| Fixed | No | No | 30 | 120 | n/a | .20 | .16 | .13 | .14 | .12 |
| Fixed | No | No | 40 | 160 | n/a | .26 | .22 | .18 | .19 | .15 |
| Fixed | Yes | No | 20 | 80 | n/a | .05 | .04 | .05 | .03 | .03 |
| Fixed | Yes | No | 30 | 120 | n/a | .10 | .07 | .07 | .05 | .07 |
| Fixed | Yes | No | 40 | 160 | n/a | .13 | .10 | .09 | .07 | .08 |
| Fixed | No | Yes | 20 | 80 | n/a | .12 | .12 | .09 | .09 | .06 |
| Fixed | No | Yes | 30 | 120 | n/a | .14 | .15 | .11 | .12 | .09 |
| Fixed | No | Yes | 40 | 160 | n/a | .16 | .18 | .13 | .17 | .11 |
| Fixed | Yes | Yes | 20 | 80 | n/a | .04 | .04 | .02 | .03 | .03 |
| Fixed | Yes | Yes | 30 | 120 | n/a | .09 | .06 | .04 | .04 | .04 |
| Fixed | Yes | Yes | 40 | 160 | n/a | .10 | .09 | .05 | .06 | .06 |
Shelf Width: 54″ (Optimal sag: 0.09″ or less, excessive: 0.27″+)
| End Support | Front Support | Rear Support | Lbs per ft | Lbs total | MDF | Plywood | Pine | Poplar | Cherry | Oak |
| Float | No | No | 20 | 90 | n/a | .25 | .27 | .14 | .18 | .13 |
| Float | No | No | 30 | 135 | n/a | .37 | .41 | .24 | .27 | .20 |
| Float | No | No | 40 | 180 | n/a | .52 | .54 | .33 | .37 | .27 |
| Fixed | No | No | 20 | 90 | n/a | .16 | .19 | .11 | .13 | .10 |
| Fixed | No | No | 30 | 135 | n/a | .25 | .28 | .19 | .21 | .15 |
| Fixed | No | No | 40 | 180 | n/a | .35 | .39 | .26 | .26 | .21 |
| Fixed | Yes | No | 20 | 90 | n/a | .08 | .07 | .06 | .08 | .05 |
| Fixed | Yes | No | 30 | 135 | n/a | .14 | .13 | .12 | .11 | .09 |
| Fixed | Yes | No | 40 | 180 | n/a | .21 | .21 | .17 | .17 | .13 |
| Fixed | No | Yes | 20 | 90 | n/a | .14 | .14 | .12 | .11 | .09 |
| Fixed | No | Yes | 30 | 135 | n/a | .20 | .18 | .14 | .15 | .11 |
| Fixed | No | Yes | 40 | 180 | n/a | .26 | .24 | .19 | .19 | .14 |
| Fixed | Yes | Yes | 20 | 90 | n/a | .07 | .06 | .04 | .06 | .04 |
| Fixed | Yes | Yes | 30 | 135 | n/a | .12 | .11 | .07 | .09 | .06 |
| Fixed | Yes | Yes | 40 | 180 | n/a | .15 | .17 | .10 | .11 | .10 |
