DIN 933 Hex Bolt Dimensions: Complete Size Chart (M6–M48)

What Is a DIN 933 Hex Bolt?

DIN 933 is the German standard for fully threaded hex head bolts with metric coarse threads. It is dimensionally equivalent to ISO 4017, so bolts made to either standard are interchangeable in most applications. The defining feature of a DIN 933 bolt is that the thread runs the entire length of the shank, right up to the underside of the head — unlike the partially threaded DIN 931 (ISO 4014) bolt, which keeps a plain shank section for shear strength.

DIN 933 hex bolts are among the most widely specified fasteners in structural steel, machinery, and general engineering. We supply DIN 933 hex head bolts in sizes M6–M48, in property classes 4.8, 8.8, 10.9 and 12.9, with zinc-plated, hot-dip galvanized and stainless steel finishes.

DIN 933 Dimension Chart (M6–M48)

The table below lists the key head and thread dimensions for the standard DIN 933 size range. All values are in millimetres. “s” is the width across flats (the wrench size), “k” is the head height, and “e” is the minimum width across corners.

Nominal Thread	Coarse Pitch P	Across Flats s	Across Corners e (min)	Head Height k
M6	1.00	10	11.05	4.0
M8	1.25	13	14.38	5.3
M10	1.50	16	17.77	6.4
M12	1.75	18	20.03	7.5
M14	2.00	21	23.36	8.8
M16	2.00	24	26.75	10.0
M18	2.50	27	29.56	11.5
M20	2.50	30	32.95	12.5
M22	2.50	34	37.29	14.0
M24	3.00	36	39.55	15.0
M27	3.00	41	45.20	17.0
M30	3.50	46	50.85	18.7
M33	3.50	50	55.37	21.0
M36	4.00	55	60.79	22.5
M42	4.50	65	71.31	26.0
M48	5.00	75	82.61	30.0

Common stock sizes: M6, M8, M10, M12, M14, M16, M18, M20, M22, M24, M27, M30, M33, M36, M42, M48. Larger diameters and fine-pitch threads are available as custom production.

Standard Length Range

DIN 933 bolts follow the ISO standard length series: 6, 8, 10, 12, 16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70–150 mm in 10 mm steps, then 160–300 mm in 20 mm steps, with longer lengths up to 500 mm produced to order. Because the shank is fully threaded, grip length is not critical for DIN 933 — you simply need a bolt at least as long as the combined thickness of the parts plus nut engagement (typically 1.5 × nominal diameter for the nut).

Property Classes and Head Marking

Carbon steel DIN 933 bolts are available in property classes 4.8, 8.8, 10.9 and 12.9:

4.8 – low-strength general purpose, unmarked head
8.8 – the most common structural grade, marked “8.8”
10.9 – high-strength, marked “10.9”
12.9 – highest strength, marked “12.9”; typically supplied with a black-oxide or phosphated finish

Stainless steel versions follow the A2-70 (304) and A4-80 (316) designations instead of property classes. The class number is stamped on the head for all bolts of class 8.8 and above, together with the manufacturer’s identification mark.

How to Specify DIN 933 Bolts When Ordering

A complete specification avoids costly mix-ups. Always include these five elements:

Standard: DIN 933 (or ISO 4017)
Size: nominal diameter × length, e.g. M12 × 50
Property class: e.g. 8.8
Finish: zinc plated, hot-dip galvanized, stainless A2/A4, or black oxide
Quantity: standard MOQ is 1,000 pcs; custom production from 5,000 pcs

Example: “DIN 933 – M12×50 – 8.8 – Hot-Dip Galvanized – 20,000 pcs.” Need a quote? Send your list through the enquiry form — standard sizes ship in 7–15 days.

DIN 933 vs DIN 931: Quick Reminder

Both are hex head bolts with identical head dimensions — the difference is the shank. DIN 933 is fully threaded (better when you need thread all the way, e.g. into nuts along varying grip lengths), while DIN 931 has a plain shank (better for shear-loaded joints). See our full comparison in DIN 931 vs DIN 933: Full-Thread vs Half-Thread Selection Guide.

Frequently Asked Questions

Is DIN 933 the same as ISO 4017?

Practically, yes. DIN 933 was withdrawn and superseded by ISO 4017, which kept the same dimensions. Bolts manufactured to either standard are interchangeable. Reputable suppliers mark or certify to both.

What is the difference between DIN 933 and ASME/ANSI hex bolts?

DIN 933 uses metric threads and metric head sizes; ASME B18.2.1 hex bolts use inch threads (1/4″, 3/8″, 1/2″ etc.) with different head proportions. A wrench sized for an M10 (17 mm across flats… actually 16 mm) will not fit a 3/8″ bolt (5/8″ across flats), so the two systems are never interchangeable. Match the standard to the mating parts in your assembly.

What sizes and finishes are readily available?

Stock covers M6–M48 in zinc-plated, hot-dip galvanized and stainless finishes. MOQ is 1,000 pcs for standard sizes, lead time 7–15 days. Larger diameters (M56, M64), fine pitch, and special lengths are custom-made in 20–30 days.

Do DIN 933 bolts need washers?

Washers are not mandatory but recommended: a flat washer (DIN 125) distributes clamping pressure and protects the mating surface, especially under hot-dip galvanized or high-strength installations. For areas with vibration, combine with the appropriate locking method.