This free tool is a real, interactive version of the classic Ashby materials-selection chart used throughout mechanical and materials engineering to compare material families at a glance. By default it plots Young's modulus (E, GPa) against density (ρ, Mg/m³) on log-log axes for roughly 38 real materials, grouped into seven families — technical ceramics, metals & alloys, composites, polymers, foams, woods, and elastomers — each shown as a shaded cluster so you can see where a whole family sits relative to the others. A toggle switches the same materials onto a second real Ashby pair, strength versus density, and a draggable material-index guideline lets you apply the actual Ashby selection method rather than just eyeballing the scatter.
Both axes use logarithmic scales because material properties span many orders of magnitude — density ranges from around 0.03 Mg/m³ for a foam to nearly 9 Mg/m³ for copper, and modulus ranges from a few MPa for an elastomer to over 400 GPa for a technical ceramic. On a log-log plot, each decade (0.01, 0.1, 1, 10...) takes up equal visual space, so families that would be invisible on a linear chart — like foams and elastomers sitting near the origin — become clearly separated clusters.
Use the toggle above the chart to switch between "Modulus – Density" (E vs ρ, the stiffness-per-weight view) and "Strength – Density" (σ vs ρ, the strength-per-weight view). Both are standard Ashby chart pairs. Composites and technical ceramics tend to move differently between the two views: ceramics are extremely stiff for their weight but comparatively less strong in practice, because their real-world strength is limited by brittle fracture rather than the theoretical bond strength the modulus reflects.
The real power of an Ashby chart is the material index: a combination of properties that measures performance for a specific design goal. For a panel that must be as light and stiff as possible, the index is M = E^(1/3) / ρ — derived from the physics of bending stiffness in a flat plate. On a log-log E-ρ plot, every material with the same value of this index falls on a straight line of slope 3; sliding that line up and to the left finds progressively better materials. This tool draws that line for you and lets you drag it directly on the chart. Switching the "structural element" dropdown between tie, beam, and panel changes the exponent (and therefore the line's slope) to match a rod in tension, a beam in bending, or a plate in bending, for both the stiffness and strength axis pairs.
As you drag the guideline, every material lying above it — meaning it has a better index than the line's current value — gets highlighted with a white ring, and the side panel lists them ranked from best to worst. This mirrors how the Ashby method is actually used in engineering practice: rather than picking the single "best" material in isolation, you narrow a shortlist by index and then apply secondary constraints (cost, corrosion resistance, manufacturability) to make a final choice. Click the legend to hide or show a family, and click any point to pin its exact density, modulus, and strength values in the "Selected material" panel.
An Ashby chart (named after Cambridge materials scientist Mike Ashby) is a log-log scatter plot of two material properties — most commonly Young's modulus vs density, or strength vs density — with material families plotted as shaded regions. It is the standard graphical tool taught in materials selection and mechanical design courses for comparing entire classes of materials rather than individual grades, and for applying material indices to find the best material for a given structural function.
A material index is a property combination, derived from the mechanics of a specific structural problem, that you maximize (or minimize) to get the best-performing, lightest design. For a plate that must resist bending while minimizing mass, the index is E^(1/3)/ρ. Because both axes are logarithmic, taking the log of the index equation produces a straight line whose slope equals the exponent in the index (3 for a panel in bending, 2 for a beam, 1 for a simple tie) — so dragging that line and reading off which materials sit above it is mathematically equivalent to solving the optimization by hand.
No — the values are genuine textbook-typical figures for each material class (e.g., steel ≈200 GPa / 7.85 Mg/m³, aluminum 6061-T6 ≈70 GPa / 2.7 Mg/m³, CFRP ≈70-150 GPa / 1.6 Mg/m³), the same kind of representative data used in materials-selection textbooks and early-stage design. Real material properties vary by supplier, heat treatment, fiber orientation, and processing, so always confirm exact values against a datasheet before finalizing a design.
Technical ceramics have very high stiffness because it comes from strong atomic/ionic bonding, but their measured strength is usually much lower and highly variable because failure is governed by brittle fracture from microscopic flaws, not by bond strength. Unidirectional composites like CFRP, by contrast, can have both high stiffness and very high strength along the fiber direction, which is exactly why they cluster near the top-right on both charts and are prized for aerospace structures where both stiffness and strength per unit weight matter.