Finishing nails are measured primarily by their length and gauge (thickness), often expressed using the "penny" system.
Understanding the Measurements
Finishing nails, used for fine woodworking and trim work where concealment is important, are measured using a combination of factors:
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Length: The length of finishing nails is usually measured in inches. They typically range from 1 inch to 4 inches.
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Gauge: The gauge refers to the thickness of the nail's shank. Gauge sizes for finishing nails commonly range from 16 to 10. A smaller gauge number indicates a thicker nail. For example, a 10-gauge nail is thicker and stronger than a 16-gauge nail.
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"Penny" System: The "penny" system is an older, less precise way to denote nail length. It uses the symbol "d" (from the Roman coin denarius). While still sometimes used, it's less common for specifying finishing nail sizes than actual inch measurements. While the relationship between "penny" weight and length isn't perfectly consistent across all nail types, it generally corresponds to length. A higher "penny" number usually suggests a longer nail.
Summary
Finishing nails are measured by their length in inches, gauge (thickness), and historically, the "penny" system, although the inch measurement is more common now. The gauge is a measure of the nail's strength.
