Wood
Screw Pilot Hole Sizing
A "pilot hole" is a hole drilled into a wood surface prior to installing a screw. Pilot holes help to:
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Prevent wood from splitting from large screws or when near the end or edge of the board.
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Make installing the screw easier in hard materials, such as oak or maple.
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Improve accuracy by providing a guide (or "pilot") path for the screw to follow.
"Freehand" installation of screws is not always accurate. When accuracy is essential, a pilot hole can help. Here's a guide for sizing your pilot hole, courtesy the Bolt Depot.
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Wood Screw Pilot Hole Size
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Screw Size
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Hard Wood
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Soft Wood
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Countersink Size
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Tapered Bit
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Straight Bit
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Tapered Bit
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Straight Bit
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2
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3/32
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1/16
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5/64
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1/16
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1/4
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3
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7/64
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5/64
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3/32
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1/16
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1/4
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4
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7/64
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5/64
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3/32
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1/16
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1/4
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5
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1/8
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3/32
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7/64
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5/64
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5/16
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6
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9/64
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7/64
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1/8
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3/32
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5/16
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7
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5/32
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7/64
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9/64
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3/32
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5/16
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8
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11/64
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1/8
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5/32
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7/64
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3/8
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9
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3/16
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9/64
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11/64
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1/8
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3/8
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10
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13/64
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9/64
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3/16
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1/8
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7/16
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12
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7/32
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5/32
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13/64
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9/64
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7/16
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14
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1/4
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11/64
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15/64
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5/32
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1/2
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16
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9/32
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3/16
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17/64
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11/64
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9/16
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18
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5/16
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7/32
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19/64
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13/64
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5/8
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20
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21/64
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15/64
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5/16
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7/32
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3/4
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24
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3/8
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17/64
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3/8
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1/4
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3/4
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