Metal Weight Calculator —
Plate, Round Bar, Tube, Hex and Square Stock, Plus the Stock Size to Buy

How the Weight Is Calculated

Weight is volume multiplied by density. The calculator computes the solid volume of the shape you entered and multiplies it by the nominal density for the alloy from the table below, in pounds per cubic inch or grams per cubic centimetre depending on the unit you chose.

Two things to keep in mind. First, mill density varies by a percent or so with temper and heat lot, so treat the result as an estimate, not a certified weight. Second, the shape you enter is a solid. If you want the weight of a finished part with pockets and holes, enter its envelope for the stock answer and accept that the finished weight will be lower; for an exact finished weight, read the mass property from the CAD model.

The Stock Size a Shop Buys, and Why It Weighs More

A machined part is cut out of a larger piece of stock. The shop needs material to clean up the mill surface, to hold the part in the vise or chuck, and to allow for the saw cut, so the stock is bigger than the part in every direction. The calculator adds your allowances to the dimensions you entered, then rounds each up to the next standard size that mills and distributors stock:

The default allowances, 0.125 in on thickness or diameter and 0.25 in on length and width, are typical for a general machine shop cutting from bar and plate. Change them to match your own practice: a saw-cut blank for a lathe part usually needs more on length than a plate part needs on width, and thin aluminum sheet parts often use zero thickness allowance because the sheet surface is the finished surface.

Density of Common Machining Alloys and Plastics

The nominal densities the calculator uses. They are the handbook values for the alloy family; individual tempers and heat lots vary by roughly one percent.[1][2]

The calculator reads its densities from this table when the page loads, so the tool and the printed values can never disagree.

Using the Numbers in an RFQ

Weight is useful in three places. Shipping: a finished-weight estimate times quantity tells you whether the order ships parcel or freight. Material budget: stock weight times a per-pound price gives the raw material line of a quote before any machining, and the buy-to-fly ratio tells you how much of that line is chips. Design review: if the ratio is high, the fixes are all on the drawing side: pick a plate thickness that matches the part, split a deep pocket part into two thinner pieces, or ask the shop whether a near-net forging or a casting blank is available for the quantity. The RFQ guide covers what else to send.