Bolt Weight Calculator

Bolt Weight Calculator: enter a standard, a size and a length, and the tool returns the theoretical weight of one piece and of 1,000 pieces. The calculation uses the standard's own head and shank geometry — hex head volume 0.866 x s squared x k, plus the shank, with the threaded portion taken at pitch diameter.

Standard

Size

Length (mm)

Material density

Nominal dimensions only. The threaded portion is taken at pitch diameter. Theoretical figure for estimating — not a weighed value.

How the calculation works

Weight is the sum of three volumes multiplied by the material density:

Hex head	0.866 × s² × k (s = width across flats, k = head height)
Plain shank	π/4 × d² × L_plain
Threaded portion	π/4 × d₂² × L_thread (d₂ = d − 0.6495 × P)
Socket head	π/4 × A² × H, less the hex socket

Every dimension (s, k, d, P) is taken from the standard itself, not estimated. The thread length for part-threaded bolts follows the standard: 2d + 6 mm up to 125 mm, 2d + 12 mm up to 200 mm, 2d + 25 mm above.

Worked example

DIN 933 M10 × 50, carbon steel. Width across flats s = 16 mm, head height k = 6.4 mm, pitch P = 1.5 mm, so d₂ = 10 − 0.6495 × 1.5 = 9.026 mm.

Head	0.866 × 16² × 6.4 = 1,419 mm³
Threaded shank (43.6 mm)	π/4 × 9.026² × 43.6 = 2,790 mm³
Total volume	4,209 mm³ = 4.209 cm³
Weight, one piece	4.209 × 7.85 = 33.0 g
Weight, 1,000 pieces	33.0 kg

Reference table — DIN 933, kg per 1,000 pieces

Size	16	20	25	30	35	40	50	60	70	80	90	100	120	140	160	180	200
M6	4.837	5.543	6.426	7.308	8.191	9.073	10.838	12.603	14.368	16.133	17.898	19.663	23.193	26.723	30.253	33.783	37.314
M8	9.498	10.772	12.365	13.957	15.55	17.143	20.329	23.514	26.7	29.885	33.071	36.257	42.628	48.999	55.37	61.741	68.113
M10	15.96	17.969	20.48	22.991	25.503	28.014	33.036	38.059	43.082	48.104	53.127	58.149	68.194	78.24	88.285	98.33	108.375
M12	22.704	25.614	29.252	32.89	36.528	40.166	47.442	54.718	61.994	69.27	76.546	83.822	98.374	112.926	127.477	142.029	156.581
M16	47.152	52.482	59.144	65.806	72.468	79.131	92.455	105.78	119.104	132.429	145.754	159.078	185.727	212.377	239.026	265.675	292.324
M20	83.766	92.093	102.503	112.913	123.323	133.733	154.552	175.372	196.192	217.011	237.831	258.651	300.29	341.929	383.568	425.208	466.847
M24	135.153	147.145	162.135	177.125	192.116	207.106	237.086	267.066	297.047	327.027	357.007	386.988	446.948	506.909	566.869	626.83	686.79
M30	268.995	275.157	298.856	322.555	346.254	369.953	417.35	464.748	512.146	559.543	606.941	654.339	749.134	843.93	938.725	1033.521	1128.316
M36	462.696	462.696	479.892	514.286	548.679	583.072	651.859	720.646	789.433	858.219	927.006	995.793	1133.366	1270.939	1408.513	1546.086	1683.66

Carbon steel at 7.85 g/cm³. Full thread (DIN 933 / ISO 4017).

Frequently asked questions

What formula does this calculator use?

Head volume is 0.866 x s x s x k for a hexagon (width across flats s, head height k). The plain shank is pi/4 x d x d x L. The threaded portion is taken at the pitch diameter d2 = d - 0.6495 x P, where P is the thread pitch. Volume is multiplied by the material density.

Why does the result differ slightly from a supplier catalogue?

Catalogues differ in how they treat the thread, the head chamfer and the under-head fillet. This tool uses nominal dimensions and the pitch diameter for the thread. Treat the result as a theoretical figure for estimating, not as a weighed value.

Where does the thread length come from for DIN 931 and ISO 4014?

Part-threaded bolts use the thread length b from the standard: 2d + 6 mm for lengths up to 125 mm, 2d + 12 mm up to 200 mm, and 2d + 25 mm above that.

Can I use this for stainless steel?

Yes. Select the density that matches the material — 7.90 g/cm3 for austenitic stainless steel, 7.85 g/cm3 for carbon steel.

Do you supply the bolts shown in the reference table?

The reference table covers DIN 933 hex head bolts. Availability, material and finish are quoted per enquiry — send the size, length, grade and quantity.