ASTM A325 Bolts Dimensions Chart, Strength, Grade A325 Structural Bolt Sizes

ASTM A325 Bolt Dimensions Chart, Sizes, Strength

ASTM A325 bolts are one of the most commonly used fasteners, usually used for structural steel connections in heavy steel structures. It contains two types of quenched and tempered steel heavy hex structural bolts:

Type 1: medium carbon, carbon boron, or medium carbon alloy steel,
Type 3: weathering steel.
Type 2: withdrawn in 1991.

The ASTM A325 standard was withdrawn in 2016 and replaced by ASTM F3125/F3125M. Except for the dimensions, the information on this page is for reference and historical purposes only.

ASTM A325 Bolts Properties & Specification

ASTM A325 material properties and specification are list in the following tables including dimensions, sizes, strength, etc.

Chemical Requirements

Chemical Requirements for Type 1 Bolts, Heat Analysis
Grades	Material	C	Si	Mn, ≤	P, ≤	S, ≤	B	Alloying Elements
ASTM A325 Type 1	Carbon Steel	0.30-0.52	0.15-0.30	0.6	0.04	0.05	–	–
	Carbon Boron Steel	0.30-0.52	0.15-0.30	0.6	0.04	0.05	0.0005-0.003	–
	Alloy Steel	0.30-0.52	0.15-0.35	0.6	0.035	0.04	–	A
	Alloy Boron Steel	0.30-0.52	0.15-0.35	0.6	0.035	0.04	0.0005-0.003	A

Chemical Requirements for Type 1 Bolts, Product Analysis
Grades	Material	C	Si	Mn, ≤	P, ≤	S, ≤	B	Alloying Elements
ASTM A325 Type 1	Carbon Steel	0.28-0.55	0.13-0.32	0.57	0.048	0.058	–	–
	Carbon Boron Steel	0.28-0.55	0.08-0.32	0.6	0.04	0.05	0.0005-0.003	–
	Alloy Steel	0.28-0.55	0.13-0.37	0.6	0.04	0.045	–	A
	Alloy Boron Steel	0.28-0.55	0.13-0.37	0.6	0.04	0.045	0.0005-0.003	A

ASTM A325 Bolt Strength

ASTM A325 bolt strength are summarized in the table bellow inluding tensile strength, yield strength and hardness, etc.

Notes:

The stress area is calculated as follows:

As = 0.7854 [D-(0.9743/n)]

As = stress area, in²,
D = nominal bolt size, and
n = threads per inch.

Tensile Requirements for Full-Size Bolts, Studs, and Threaded Rod
Bolt Size, Threads per Inch, and Series Designation	Stress Area, in.	Tensile Load, lbf, ≥	Proof Load, Length Measurement Method	Alternative Proof Load, Yield Strength Method
1/2 – 13 UNC	0.142	17,050	12,050	13,050
5/8 – 11 UNC	0.226	27,100	19,200	20,800
3/4 – 10 UNC	0.334	40,100	28,400	30,700
7/8 – 9 UNC	0.462	55,450	39,250	42,500
1 – 8 UNC	0.606	72,700	51,500	55,750
1 1/8 – 7 UNC	0.763	80,100	56,450	61,800
1 1/4 – 7 UNC	0.969	101,700	71,700	78,500
1 3/8 – 6 UNC	1.155	121,300	85,450	93,550
1 1/2 – 6 UNC	1.405	147,500	104,000	113,800

A325 bolt grade loads tabulated are based on the following:

Bolt Size, in.	Tensile Strength, ksi	Length Measurement Method, ksi	Yield Strength Method, ksi
1/2 to 1	120	85	92
1 1/8 to 1 1/2	105	74	81

Hardness Requirements

Hardness Requirements for Structural Bolts, Studs, and Threaded Rod
Bolt Size, in	Nominal Length, in.	Hardness
		Brinell, HB	Rockwell B
1/2 – 1	< 2D	253-319	25-34
	2D, ≥	≤319	≤34
1 1 /8 – 1 1 /2	< 3D	223-286	19-30
	3D, ≥	≤286	≤30
D = Nominal diameter or thread size.

A325 Bolt Dimensions Chart

ASTM A325 bolt dimensions chart and sizes are listed in the table and drawing below.

Notes of Parameter for ASTM A325 bolts in ASME B18.2.6 -2019

Table 2.1-1, Dimensions of Heavy Hex Structural Bolts A325
Nominal Size or Basic Product Diameter, inch	Body Diameter (Max-Min), E	Width Across Flats, F		Width Across Corners, G	Head Height, H		Radius of Fillet, R	Thread Length, L T	Transition Thread Length, Y	Maximum Total Runout of Bearing Surface, FIM
Nominal Size or Basic Product Diameter, inch	Body Diameter (Max-Min), E	Nominal	Max-Min	Width Across Corners, G	Nominal	Max-Min	Radius of Fillet, R	Thread Length, L T	Transition Thread Length, Y	Maximum Total Runout of Bearing Surface, FIM
1/2 (0.500)	0.515-0.482	7/8	0.875-0.850	1.010-0.969	5/16	0.323-0.302	0.031-0.009	1.00	0.19	0.016
5/8 (0.625)	0.642-0.605	1 1/16	1.062-1.031	1.227-1.175	25/64	0.403-0.378	0.062-0.021	1.25	0.22	0.019
3/4 (0.750)	0.768-0.729	1 1/4	1.250-1.212	1.443-1.383	15/32	0.483-0.455	0.062-0.021	1.38	0.25	0.022
7/8 (0.875)	0.895-0.852	1 7/16	1.438-1.394	1.660-1.589	35/64	0.563-0.531	0.062-0.031	1.50	0.28	0.025
1 (1.000)	1.022-0.976	1 5/8	1.625-1.575	1.876-1.796	39/64	0.627-0.591	0.093-0.062	1.75	0.31	0.028
1 1/8 (1.125)	1.149-1.098	1 13/16	1.812-1.756	2.093-2.002	11/16	0.718-0.658	0.093-0.062	2.00	0.34	0.032
1 1/4 (1.250)	1.277-1.223	2	2.000-1.938	2.309-2.209	25/32	0.813-0.749	0.093-0.062	2.00	0.38	0.035
1 3/8 (1.375)	1.404-1.345	2 3/16	2.188-2.119	2.526-2.416	27/32	0.878-0.810	0.093-0.062	2.25	0.44	0.038
1 1/2 (1.500)	1.531-1.470	2 3/8	2.375-2.300	2.742-2.622	15/16	0.974-0.902	0.093-0.062	2.25	0.44	0.041

A325 Nut Dimensions

Table 3.1-1, Dimensions of Heavy Hex Nuts for Use With Structural Bolts
Nominal Size or Basic Major Diameter of Thread, in.	Width Across Flats, F		Width Across Corners, G	Thickness, H		Radius of Fillet, R	Total Runout of Bearing Face FIM, Heavy Hex Nuts, Specified Proof Load
Nominal Size or Basic Major Diameter of Thread, in.	Nominal, in.	Max-Min, in.	Width Across Corners, G	Nominal, in.	Max-Min	Radius of Fillet, R	<150 ksi	≥150 ksi
1/2 (0.500)	7/8	0.875-0.850	1.010-0.969	31/64	0.504-0.464	0.031-0.009	0.023	0.016
5/8 (0.625)	1 1/16	1.062-1.031	1.227-1.175	39/64	0.631-0.587	0.062-0.021	0.025	0.018
3/4 (0.750)	1 1/4	1.250-1.212	1.443-1.383	47/64	0.758-0.710	0.062-0.021	0.027	0.020
7/8 (0.875)	1 7/16	1.438-1.394	1.660-1.589	55/64	0.885-0.833	0.062-0.031	0.029	0.022
1 (1.000)	1 5/8	1.625-1.575	1.876-1.796	39/64	1.012-0.956-	0.093-0.062	0.031	0.024
1 1/8 (1.125)	1 13/16	1.812-1.756	2.093-2.002	1 7/64	1.139-1.079	0.093-0.062	0.033	0.027
1 1/4 (1.250)	2	2.000-1.938	2.309-2.209	1 7/32	1.251-1.187	0.093-0.062	0.035	0.030
1 3/8 (1.375)	2 3/16	2.188-2.119	2.526-2.416	1 11/32	1.378-1.310	0.093-0.062	0.038	0.033
1 1/2 (1.500)	2 3/8	2.375-2.300	2.742-2.622	1 15/32	1.505-1.433	0.093-0.062	0.041	0.036

A325 Washer Dimensions

Table 4.1.1-1, Dimensions for Hardened Steel Circular and Circular Clipped Washers

Basic Size or Nominal Washer Size, inch	Inside Diameter, I.D.		Outside Diameter, O.D.		Thickness, T	Minimum Edge Distance, E
Basic Size or Nominal Washer Size, inch	Nominal	Max-Min	Nominal	Max-Min	Max-Min	Minimum Edge Distance, E
1/2 (0.500)	0.531	0.531-0.563	1.063	1.031-1.095	0.097-0.177	0.438
5/8 (0.625)	0.688	0.688-0.720	1.313	1.281-1.345	0.122-0.177	0.547
3/4 (0.750)	0.813	0.813-0.845	1.469	1.437-1.501	0.122-0.177	0.656
7/8 (0.875)	0.938	0.938-0.970	1.750	1.718-1.782	0.136-0.177	0.766
1 (1.000)	1.063	1.063-1.085	2.000	1.937-2.063	0.136-0.177	0.875
1 1/8 (1.125)	1.188	1.188-1.251	2.250	2.187-2.313	0.136-0.177	0.984
1 1/4 (1.250)	1.375	1.375-1.438	2.500	2.437-2.563	0.136-0.177	1.094
1 3/8 (1.375)	1.500	1.500-1.563	2.750	2.687-2.813	0.136-0.177	1.203
1 1/2 (1.500)	1.625	1.625-1.688	3.000	2.937-3.063	0.136-0.177	1.313

Table 4.2.1-1, Dimensions of Hardened Beveled Washers With Slope or Taper in Thickness 1:6
Basic Size or Nominal Washer Size, inch	Inside Diameter, I.D.		Minimum Side Length, A	Thickness, T	Minimum Edge Distance, E
Basic Size or Nominal Washer Size, inch	Nominal	Max-Min	Minimum Side Length, A	Thickness, T	Minimum Edge Distance, E
1/2 (0.500)	0.531	0.531-0.563	1.75	0.313	0.438
5/8 (0.625)	0.688	0.688-0.720	1.75	0.313	0.547
3/4 (0.750)	0.813	0.813-0.845	1.75	0.313	0.656
7/8 (0.875)	0.938	0.938-0.970-	1.75	0.313	0.766
1 (1.000)	1.125	1.125-1.188	1.75	0.313	0.875
1 1/8 (1.125)	1.250	1.250-1.313	2.25	0.313	0.984
1 1/4 (1.250)	1.375	1.375-1.438	2.25	0.313	1.094
1 3/8 (1.375)	1.500	1.500-1.563	2.25	0.313	1.203
1 1/2 (1.500)	1.625	1.625-1.688	2.25	0.313	1.313

Table 5.1-1, Dimensions for Compressible Washer-Type Direct Tension Indicators, inch
Direct Tension Indicator Size	All Types				Types 325-1, 325-3	Types 490-1, 490-3
Direct Tension Indicator Size	Inside Diameter, A (Min-Max)	Protrusion Tangential Diameter, B, ≤	Thickness, Without Protrusion, E, ≥	With Protrusion, F, ≤	Outside Diameter, C (Min-Max)	Outside Diameter, C (Min-Max)
1/2 (0.500)	0.520-0.527	0.788	0.104	0.18	1.031-1.187	1.031-1.375
5/8 (0.625)	0.651-0.658	0.956	0.126	0.22	1.281-1.375	1.281-1.625
3/4 (0.750)	0.783-0.790	1.125	0.126	0.24	1.437-1.625	1.437-1.750
7/8 (0.875)	0.914-0.921	1.294	0.142	0.26	1.718-1.875	1.718-2.000
1 (1.000)	1.043-1.052	1.463	0.158	0.27	1.937-2.000	1.937-2.250
1 1/8 (1.125)	1.174-1.183	1.631	0.158	0.28	2.187-2.250	2.187-2.500
1 1/4 (1.250)	1.306-1.315	1.800	0.158	0.28	2.437-2.500	2.437-2.750
1 3/8 (1.375)	1.437-1.446	1.969	0.158	0.28	2.687-2.750	2.687-3.000
1 1/2 (1.500)	1.568-1.577	2.138	0.158	0.28	2.937-3.000	2.937-3.250

Dimensions of Twist-Off-Type Structural Bolts

Table 6.1.1-1, Dimensions of Twist-Off-Type Structural Bolts: Heavy Hex Head and Round Head Configurations
Nominal Size or Basic Major Diameter or Thread and Threads per Inch	Heavy Hex Head		Heavy Heit and Round Head		Round Head		Radius of Fillet, R (Max-Min.)	Thread Length, Lr	Spline Length, Ls	Spline Width Across Flats, S	Maximum Center of Groove to First Fully Formed Thread, U	Transition Thread Length, Y	Maximum Total Runout of Bearing Surface FIM,
	Width Across Flats, F (Max-Min.)	Width Across Corners, G (Max-Min.)	Head Height, H (Max-Min.)	Full Size Body Dia. E (Max-Min.)	Head Dia. D, ≤	Bearing Dia. C, ≥	Radius of Fillet, R (Max-Min.)	Thread Length, Lr	Spline Length, Ls	Spline Width Across Flats, S	Maximum Center of Groove to First Fully Formed Thread, U	Transition Thread Length, Y	Maximum Total Runout of Bearing Surface FIM,
1/2 – 13 (0.500)	0.875-0.850	1.010-0.969	0.323-0.302	0.515-0.482	1.126	0.89	0.031-0.009	1.00	0.50	0.32	0.192	0.19	0.016
5/8 – 11 (0.625)	1.062-1.031	1.227-1.175	0.403-0.378	0.642-0.605	1.313	1.102	0.062-0.021	1.25	0.60	0.43	0.227	0.22	0.019
3/4 – 10 (0.750)	1.250-1.212	1.443-1.383	0.483-0.455	0.768-0.729	1.58	1.338	0.062-0.021	1.38	0.65	0.53	0.25	0.25	0.022
7/8 – 9 (0.875)	1.438-1.394	1.660-1.589	0.563-0.531	0.895-0.852	1.88	1.535	0.062-0.031	1.50	0.72	0.61	0.278	0.28	0.025
1 – 8 (1.000)	1.625-1.575	1.876-1.796	0.627-0.591	1.022-0.976	2.158	1.771	0.093-0.062	1.75	0.80	0.7	0.313	0.31	0.028
1 1/8 – 7 (1.125)	1.812-1.756	2.093-2.002	0.718-0.658	1.149-1.098	2.375	1.991	0.093-0.062	2.00	0.90	0.8	0.367	0.34	0.032
1 1/4 – 7 (1.250)	2.000-1.938	2.309-2.209	0.813-0.749	1.277-1.223	2.76	2.213	0.093-0.062	2.00	1.00	0.9	0.367	0.38	0.035

ASTM A307 Bolts, ASTM A572 Grade 50 Steel, AISI 304 Stainless Steel

Bolts Carbon Steel