Workshop reference
Material Density Reference
Approximate densities for common workshop materials.
| Material | lb/in³ | lb/ft³ | kg/m³ |
|---|---|---|---|
| Aluminum | 0.0975 | 168.5 | 2700 |
| Mild steel | 0.283 | 489 | 7850 |
| Stainless steel | 0.289 | 499 | 8000 |
| Brass | 0.307 | 531 | 8500 |
| Copper | 0.323 | 559 | 8960 |
| Acrylic | 0.043 | 74 | 1190 |
| Hard maple, approximate | 0.025 | 43 | 690 |
| Red oak, approximate | 0.025 | 44 | 700 |
Wood density changes with species, individual board, and moisture content. Metals and plastics also vary by alloy and formulation. Use a supplier specification when the weight matters.
Use the chart as a starting point
Reference values help compare sizes and plan a job. Product specifications, codes, tolerances, and the actual material still control the final choice.
Sage's guided lesson
Density is a shortcut, not a guarantee
A density chart lets you estimate the weight of a part before you cut it, ship it, or load it. This lesson covers what the numbers actually mean, how to turn them into a usable weight estimate, and why a single number can never capture everything about a real piece of material.
Weight packed into a space
What density actually tells you
Density is simply weight divided by volume: how much a given amount of space, filled with a given material, actually weighs. Two blocks the exact same size can have wildly different weights depending on what they are made of, which is exactly why a density chart is useful before you commit to shipping, lifting, or mounting something.
The values on this chart are typical figures for common workshop materials. Real material varies by alloy, species, moisture content, and manufacturing process, so treat these numbers as a solid starting estimate rather than a certified specification.
Use density to get in the right neighborhood for planning. Use a supplier's material certification or an actual scale reading when the weight has to be exact.
Turning density into a weight
Using density to estimate weight
Multiply the volume of your part by the density value for that material, keeping the units consistent. If your part's volume is in cubic inches, use the pounds per cubic inch column. If it is in cubic feet, use the pounds per cubic foot column instead.
Worked example
A mild steel block is 2 in × 3 in × 10 in = 60 in³60 in³ × 0.283 lb/in³ ≈ 17 lbThe Material Weight Calculator and Lumber Weight Calculator do this math automatically, including shapes like rods and tubes where the volume formula is less obvious than a simple block.
I know this is off topic, but this reminds me of a joke I heard when teaching this to one of my interns, Why did the crab never share? Because he's shellfish. Yeah, I don’t see the connection either, but I think it is cute!
Before you trust the estimate
Tips and common mistakes
- Wood density changes significantly with moisture content. A green board can weigh noticeably more than the same board fully dried.
- Alloys within the same metal family, like different stainless steel grades, can vary enough in density to matter for precise weight budgets.
- Do not forget to subtract hollow sections, holes, or cutouts from the volume before multiplying by density, or the weight estimate will run high.
For shipping quotes, structural loads, or anything safety related, confirm the actual material weight with a supplier spec sheet or a scale rather than relying on a general chart alone.
Where this idea came from
A little history
The idea of comparing materials by weight for a given volume goes back at least to the ancient world, most famously in the story of Archimedes using water displacement to check whether a crown was pure gold or mixed with a cheaper metal. That same basic principle, weight compared to volume, is still exactly what a modern density chart is built on.
Formal density tables for engineering materials became standard as manufacturing scaled up and shipping, structural design, and material substitution all needed a fast, reliable way to estimate weight before a part was ever built.
That carries some weight
Class is over. It is officially cheese fries time.
You now know what density really measures and how to turn it into a usable weight estimate before you cut, ship, or mount anything. That earns cheese fries, Sage's favorite way to celebrate a finished lesson.
Quick answers
Material density questions
Why do wood density values say "approximate"?
Wood density changes with species, individual board, and especially moisture content, so a single chart value is a useful estimate rather than an exact figure for any specific board.
How do I estimate the weight of a metal part?
Calculate the part's volume, then multiply by the density value for that metal in matching units. The Material Weight Calculator handles blocks, rods, and tubes automatically.
Do different grades of the same metal have different densities?
Yes, though usually only slightly. Different stainless steel or aluminum alloys can vary enough to matter for precise weight budgets, so check a supplier spec sheet when precision counts.
Why does density matter for shipping estimates?
Shipping costs are often based on weight, and density lets you estimate a part's weight from its dimensions before it is ever built or measured on a scale.