Replacing fiberglass with carbon fiber
This is the one swap where solid-for-solid often does make sense — carbon is roughly twice as stiff per ply as E-glass and lighter too.
E-glass laminate is around 25 GPa at ~1.85 g/cc; a balanced carbon laminate is roughly 50 GPa at ~1.55 g/cc. So unlike aluminum or steel, going carbon buys you both more stiffness per ply and less weight at the same time. A like-for-like layup in carbon is genuinely stiffer and lighter — the only real question is whether the upgrade is worth carbon’s higher fiber cost (broadly 3× glass).
If you’re already laying up glass, the cleanest decision is usually: keep the same part, switch the fabric. You’ll either hit your old stiffness with fewer plies and less weight, or keep the plies and gain stiffness. And a carbon sandwich still beats both on stiffness-per-weight if your geometry has room for a core.
The default below is a 1/8″ (3.175 mm) fiberglass panel at 12×12″. Tune it to your part to see how a carbon swap — solid or sandwich — compares.
Baseline
Carbon alternatives
Verdict: fiberglass-to-carbon is the easy upgrade — stiffer and lighter at once. It’s a pure cost-vs-performance call.
When monolithic carbon actually makes sense
- Thin parts where a sandwich won’t fit. If you only have a couple millimeters of envelope, you can’t add core. Solid carbon still trims weight — useful for moving mass (rotating, reciprocating, hand-held).
- Fastener-heavy parts. Sandwiches need potted inserts at every screw location, which adds labor and tooling. Below some part count, solid is simpler.
- Cosmetic surfaces. If the part is the visual — a dash, a body panel, a cover — solid weave is what people are paying for.
Where to buy
The calculator output is a spec, not an order. For one-off or low-volume purchases, standard composite stock distributors carry pre-made carbon sheets and sandwich panels in common sizes:
- Rock West Composites — broad selection of sheets, tubes, and pre-fab sandwich panels.
- Dragon Plate — solid + sandwich CF panels with good customer-facing specs.
- ACP Composites — sheets, tubes, raw fabric.
- Layup Parts — custom-cut composite parts on demand.