1. Measure the shape
Round bar: measure the diameter across a clean spot with calipers. Hex bar: measure across the flats. Flat bar and plate: measure thickness and width. Note whether the surface is rough or drawn.
Guides · Measuring · Solids only
How to weigh and measure a metal drop before you send it in
A buyer's first questions about a bar end or plate drop are what alloy, what size, how many and roughly how heavy. You can answer the weight without a scale: measure the piece, work out its volume and multiply by the alloy's density. A labeled piece you can measure is a blank for the next shop, so it is worth describing well.
What to measure, step by step
Calipers and a tape measure are enough. Measure in inches.
2. Measure the usable length
Measure the length you could actually cut a part from. Leave out a tapered end, a crack or heavy saw damage.
3. Work out the volume
Round: 3.1416 x (diameter / 2)² x length. Hex: 0.866 x across-flats² x length. Plate or flat bar: thickness x width x length. Use inches, so the answer is in cubic inches.
4. Multiply by the density
Multiply the cubic inches by the alloy's density in lb/in³ from the table on this page. The result is an estimate in pounds. A scale reading is better if you have one.
5. Count the pieces and send it in
Note the piece count, the dimensions and the estimated or scale weight. Send photos with a tape measure in frame and the stamps visible through the sell form or to buyers@machineshopscrap.com.
Estimate the weight: volume x density
Work out the volume in cubic inches, then multiply by the density in pounds per cubic inch (lb/in³).
Volume formulas
- Round bar: 3.1416 x (diameter / 2)² x length
- Hex bar: 0.866 x across-flats² x length
- Plate, flat bar or block: thickness x width x length
Worked example (example only)
A made-up piece, not our inventory: a 304 stainless round, 3.0 in diameter and 6.0 in long.
- Volume = 3.1416 x 1.5² x 6.0 = about 42.4 in³
- Weight = 42.4 x 0.289 = about 12.3 lb
Approximate densities
Typical published values. They are approximate and vary slightly by exact grade and temper. They are for estimating weight only, not offer data.
| Material | lb/in³ | g/cm³ | Published source |
|---|---|---|---|
| Aluminum 6061 | about 0.0975 | 2.70 | MatWeb 6061-T6 datasheet (Aluminum Association typical) |
| Aluminum 7075 | about 0.102 | 2.81 | MatWeb 7075-T6 datasheet (Aluminum Association typical) |
| Carbon and alloy steel (1018, 4140) | about 0.284 | 7.85 to 7.87 | MatWeb AISI 1018 and 4140 datasheets |
| Stainless 304 and 316 | about 0.289 | 8.00 | AmesWeb density of steel table |
| Titanium 6Al-4V (Grade 5) | about 0.160 | 4.43 | Aerospace Specification Metals Ti-6Al-4V datasheet |
| Inconel 718 | about 0.296 (annealed) | 8.19 | Special Metals INCONEL alloy 718 bulletin |
| Brass 360 (C36000) | about 0.307 | 8.49 to 8.50 | National Bronze C36000 datasheet |
| Copper C110 (C11000) | about 0.321 to 0.323 | 8.89 to 8.94 | Hussey Copper C11000 datasheet |
| Cobalt-bonded tungsten carbide | about 0.51 to 0.54, varies by grade | 14.0 to 14.9 (about 14.5 for a 10% cobalt grade) | General Carbide designer's guide and H.B. Carbide grade chart |
Carbide: the density depends on how much cobalt binder is in the grade. See solid carbide and what carbide rod and blanks are worth. Brass, bronze and copper: see selling brass, bronze and copper drops.
Why the weight is only half the picture
Two drops of the same weight can be very different lots. The alloy ID and the paperwork decide whether a piece is reusable stock or melt. If a piece is unmarked, see how to identify unmarked drops. If you have the mill test report, see how mill certs raise the offer.
A scale reading beats a calculation, but either is fine for a first review. Just say which one you used.
What to send
- Photos of the lot with a tape measure in frame.
- Close-ups of stamps, paint codes or supplier tags.
- Dimensions, piece count and the estimated or scale weight.
- The alloy if you know it, and any cert or packing slip.
- Your ZIP code.
Submit it on the sell form or email buyers@machineshopscrap.com. A person reviews it and makes an offer. There's no posted price per pound. See how we value.
Weighing and measuring FAQ
Do I need a scale?
No. Dimensions plus the alloy are enough for a first review. A scale reading is welcome if you have one.
What if I don't know the alloy?
Send photos of any stamps, supplier tags or paperwork. See how to identify unmarked drops. An unknown alloy still gets reviewed, but a clear ID helps.
Do you buy by the pound?
We don't post a per-pound price. Each lot is reviewed as reusable stock by a person, and the weight is one part of that review.
Does hollow or tubular stock count?
The formulas on this page are for solid pieces. We review solid bar, plate, rod and blocks. No chips, turnings, swarf or mixed scrap.
How accurate is the density table?
It is approximate. The figures are typical published values, and the exact grade and temper shift them slightly. A scale reading beats the calculation.