牙距

            
公制螺紋牙距表 美制 統一標準螺紋牙數表
公稱直徑 牙距 mm 公稱直徑 直徑尺寸 牙距＝每英寸牙數
毫米 粗牙 細牙 號＜ 1/4" 英寸 in 毫米 mm 粗牙 UNC 細牙 UNF
M1               0.25                   0.2
M1.2             0.25                   0.2
M1.6             0.35                   0.2
M2               0.4                    0.25 
M2.5             0.45                   0.35
M3               0.5                    0.35
M4               0.7                    0.5
M5               0.8                    0.5 
M6               1                      0.75
M8               1.25                    1 
M10              1.5                    1.25
M12              1.75                   1.25
M14              2                      1.5 
M16              2                      1.5
M18              2.5                    1.5 
M20              2.5                    1.5 
M22              2.5                    1.5 
M24              3                      2
M27              3                      2 
M30              3.5                    2
(M33)            3.5                    2
M36              4                      3
(M39)            4                      3 
M42              4.5                    3
(M45)            4.5                    3
M48              5                      3