COUNTERBORE HOLE DIMENSIONS CHART (METRIC)

Counterbore hole dimensions chart for metric socket head cap screws.

Counterbore Hole Dimensions Chart
Nom. Size or Basic Screw Dia.	Normal Drill Size, A		H	X	Y
	Close Fit	Normal Fit
M1.6	1.80	1.95	1.60	3.50	2.0
M2	2.20	2.40	2.00	4.40	2.6
M2.5	2.70	3.00	2.50	5.40	3.1
M3	3.40	3.70	3.00	6.50	3.6
M4	4.40	4.80	4.00	8.25	4.7
M5	5.40	5.80	5.00	9.75	5.7
M6	6.40	6.80	6.00	11.25	6.8
M8	8.40	8.80	8.00	14.25	9.2
M10	10.50	10.80	10.00	17.25	11.2
Nom. Size or Basic Screw Dia.	Normal Drill Size, A		H	X	Y
	Close Fit	Normal Fit
M12	12.50	12.80	12.00	19.25	14.2
M14	14.50	14.75	14.00	22.25	16.2
M16	16.50	16.75	16.00	25.50	18.2
M20	20.50	20.75	20.00	31.50	22.4
M24	24.50	24.75	24.00	37.50	26.4
M30	30.75	31.75	30.00	47.50	33.4
M36	37.00	37.50	36.00	56.50	39.4
M42	43.00	44.00	42.00	66.00	45.6
M48	49.00	50.00	48.00	75.00	52.6

Note ¹: X - Counterbore Diameter, Y - Countersink Diameter, H - Counterbore Depth / Max. Head Height for Socket Head Cap Screw

Note ²: All dimensions are in mm.

Supplements:

• Thread calculators and charts
• Metric counterbore hole dimensions calculator

Reference:

• Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
• Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.