Bolt Weight Calculator
Weigh the whole set, not just the bolt. Pick a diameter, enter the length under the head, add a nut and washers the way the joint is actually assembled, and read the per-piece and total weight for your order — in grams or ounces, kilograms or pounds, on the same screen.
Fastener Set Inputs
Standard finished hex nut — the common pairing for a hex bolt
Wider and thicker; the structural pattern used with A325/A490 hardware
1 under the head, 1 under the nut — up to 4 if both faces of the joint are protected
Total Weight — 100 Complete Sets
4.698 kg
≈ 10.358 lb · 4,698 g
400 individual pieces of hardware in the order
Weight Breakdown
How this was computed
W_set = W_head + W_shank + Σ (W_accessory × qty/bolt)
= 10.10 + 24.66 + 8.04×1 + 2.10×2 = 46.98 g per set
Steel density ρ = 7.85 g/cm³ (0.2833 lb/in³). Head: hex prism, AF = 1.5·d, height 0.66·d. Standard nut: AF = 1.5·d, thickness 0.88·d, tapped hole deducted. Heavy nut: AF = 1.5·d + 3.2 mm, thickness 1.0·d. Washer: OD 2·d, ID 1.08·d, thickness 0.12·d. Weights above are in grams, the model's home unit.
Model Assumptions
Every figure on this page comes from nominal ASME-style hex proportions times the density of plain carbon steel — the same basis as classic Portland-Bolt weight charts.
Hex head
AF = 1.5·d, height 0.66·d
Standard hex nut
AF = 1.5·d, thickness 0.88·d
Heavy hex nut
AF = 1.5·d + 3.2 mm, thickness 1.0·d
Flat washer
OD 2·d, ID 1.08·d, thickness 0.12·d
Shank
plain cylinder, full nominal diameter
Density
7.85 g/cm³ — scale for other materials
Why Bolt Weight Matters
Weight is one of those fastener numbers that seems trivial until it isn't. A single 3/4" hex bolt weighs about half a pound — nothing to write home about. But a joint with two hundred of them, on a truck with fifty other joints, quietly turns into a quarter ton of steel that someone has to lift, ship, pay for, and design around. Estimating that mass before the order ships is what this page is for, and the five situations below are where the estimate earns its keep.
Freight and shipping costs
Less-than-truckload and parcel carriers price by weight bands, and fasteners are dense enough to hit those bands fast. A pallet of structural bolt sets can weigh 900 kg (2,000 lb) without looking like much, and the difference between 480 kg and 520 kg on a skid can move the quote into the next rate class. Weighing the sets here — then adding packaging — gives you a defensible number for the bill of lading instead of a guess.
Lifting and rigging decisions
Whenever bolt crates get picked by crane or forklift, the rigging is chosen against the load. A skid of M24 assemblies at 120 kg per hundred sets adds up quickly, and underestimating it turns oversized shackles into a safety topic rather than a purchasing line. The total-weight figure is the raw steel mass; add container weight and a sensible safety factor before anyone hooks anything to it.
Structural dead load
Steel designers carry connection hardware in the dead-load budget. Across a large structure, fasteners typically account for roughly one to three percent of the connected steel weight — small, but not zero, and it lands at the top of the frame where it matters most for uplift and seismic checks. A quick per-set weight × quantity calculation documents the assumption instead of leaving it to a rule of thumb.
Cost estimating and quoting
Fastener suppliers quote by the piece but buy by the pound, so weight is the bridge between the two. Estimators converting a drawing takeoff into a material budget use set weight to sanity-check quantities, price inbound freight, and predict scrap. The same math runs in reverse for demolition and salvage work, where bundled hardware is valued by recovered steel tonnage.
Counting and inventory by weight
Counting thousands of small bolts by hand is slow and error-prone, so shops count by weight instead: weigh a sample of ten, weigh the bin, divide. That trick only works if you know what one piece should weigh — which is exactly what the per-bolt figure in this calculator gives you. It also makes cycle counts and kitted-job audits dramatically faster.
One caution applies to all five: these are nominal steel weights. Galvanizing can add several percent, heavy hex and structural patterns differ from light commercial ones, and special thread lengths change the shank volume. Use the numbers for estimating, logistics, and design budgets — and weigh a real sample before anything contractual depends on the answer.
How the Bolt Weight Calculator Works
Nothing here is a lookup table — every number the tool prints comes from multiplying a geometric volume by the density of steel. That makes the model fully transparent: you can reproduce any figure on this page with a pocket calculator, and you can see exactly which simplifications are built in. The total is just the sum of the parts of the set:
m = (V_head + V_shank + V_nut + V_washer) × ρ
ρ = 7.85 g/cm³ for plain carbon steel = 0.2833 lb/in³ = 7850 kg/m³
- Hex head — a hexagonal prism with width across flats AF = 1.5·d and height 0.66·d. A hexagon written in terms of its across-flats dimension has area A = (√3/2)·AF², so the head volume is (√3/2)·(1.5·d)²·(0.66·d). The 1.5·d across-flats proportion is the standard hex pattern of ASME B18.2.1 / ISO 4014.
- Shank — a plain cylinder of the nominal diameter d and the length you enter, measured under the head: V = (π/4)·d²·L. This is the piece of the model where your input matters most, because weight scales linearly with length.
- Standard hex nut — the same hex prism at AF = 1.5·d with thickness 0.88·d, minus the tapped hole (π/4·d²·t). The hole deduction matters: it removes about a quarter of the gross prism.
- Heavy hex nut — wider and thicker: AF = 1.5·d + 3.2 mm (about 1/8") and thickness 1.0·d. Both dimensions grow, which is why the heavy pattern weighs roughly 25–40% more than a standard nut of the same size.
- Flat washer — a ring with OD = 2.0·d, ID = 1.08·d and thickness 0.12·d: V = (π/4)·(OD² − ID²)·t. Individually the lightest part of the set, but rarely alone — most joints carry two.
All of the arithmetic runs in millimeters and grams internally, whatever unit system you are typing in. Switch from metric to imperial and the calculator converts the values you already entered — a 40 mm length becomes 1.575 in, the results re-label from grams to ounces — so the physics never moves behind your back. The same shared geometry library powers the other calculators on this site, which is why an M16 head weighs the same here as it does anywhere else on the domain.
What the model deliberately ignores: thread crests cut into the shank (a fully threaded stud is a few percent lighter than the plain-cylinder assumption), chamfered washer faces, the bevel under the head, head stampings, and any coating. For hot-dip galvanized hardware add roughly 3–6%; for electroplated zinc, under 1%. Real production bolts scatter within about ±5% of these nominal values — comfortable for freight quotes and dead-load budgets, and never a substitute for a scale when a certified weight is required.
Example: 250 Galvanized M16 × 60 Sets
Say a job needs 250 complete sets — M16 × 60 mm hex bolt, one standard hex nut, and two flat washers each. On paper, piece by piece: the head is a hex prism with AF = 24 mm and height 10.56 mm; the shank is a 16 mm × 60 mm cylinder. Multiply each volume by 7.85 g/cm³ and you get:
head = (√3/2)·24² · 10.56 · 0.00785 = 41.3 g
shank = (π/4)·16² · 60 · 0.00785 = 94.7 g
bolt = 41.3 + 94.7 = 136.0 g
nut = 32.9 g · washer = 8.6 g × 2
set = 136.0 + 32.9 + 17.2 = 186.1 g
order = 186.1 g × 250 = 46.5 kg ≈ 102.6 lb
Check it in the calculator: with metric selected, set the diameter to 16, the length to 60, the quantity to 250, leave the hex nut on at one per bolt and the washers at two, and the breakdown panel reproduces every line above — head and shank separately, nut and washer subtotals, and the 46.5 kg total. That is the point of printing the substituted numbers: the tool and the back of an envelope should always agree.
Now the practical layer: hot-dip galvanizing on that order adds roughly 4%, so plan the shipment around 48.4 kg of coated steel plus cartons and a 22 kg pallet. If the same job were quoted in heavy hex nuts instead of standard, the nut line alone climbs from 8.2 kg to about 13.8 kg across the order — the difference between a heavy pattern and a light one is real money at this scale.
Hex Bolt Weight Reference Table
The table below is generated in your browser from the same geometry functions the calculator uses — it is not transcribed from a catalog, so it always agrees with the tool above. It lists the single-piece bolt weight (head + shank, no nut or washer) for common diameters at four shank lengths. To build a full set weight, add the nut and washer lines from the breakdown panel: a standard hex nut weighs roughly a quarter of a short bolt, and each nominal flat washer adds a few grams across this range. Lengths between the columns scale linearly — every extra 25 mm of shank adds (π/4)·d²·25 mm × 7.85 g/cm³, about 12 g for a 16 mm bolt.
| Size | 25 mm | 50 mm | 75 mm | 100 mm |
|---|---|---|---|---|
| M8 | 15.0 | 24.9 | 34.8 | 44.6 |
| M10 | 25.5 | 40.9 | 56.3 | 71.7 |
| M12 | 39.6 | 61.8 | 84.0 | 106.2 |
| M14 | 57.9 | 88.1 | 118.3 | 148.5 |
| M16 | 80.8 | 120.3 | 159.7 | 199.2 |
| M20 | 142.4 | 204.1 | 265.7 | 327.4 |
| M24 | 228.3 | 317.1 | 405.9 | 494.7 |
| M30 | 411.3 | 550.0 | 688.7 | 827.5 |
Units: grams per bolt (head + shank), shank lengths in mm. Switch the unit system in the calculator to flip the whole table between M8–M30 in grams and 1/4"–1" in pounds. Values are nominal steel; galvanized parts run a few percent heavier.
Bolt Weight FAQ
The questions this calculator gets asked most, answered with the same geometry the tool runs.
How much does a hex bolt weigh?
Does the weight include the bolt head?
Why does my real bolt weigh more or less than the calculated value?
How do I estimate the shipping weight of a fastener order?
What is the difference between a hex nut and a heavy hex nut in weight?
Can I use this calculator for stainless, brass, or aluminum fasteners?
How accurate is the weight reference table?
Related Bolt Calculators
Weight is the logistics side of the fastener — size the joint itself with the companion tools.