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Flexural strength

Flexural (bending) strength tells you how much bending load a material takes before it breaks or yields. Here is how to read it.

3 min read · Updated October 11, 2026 · Numbers update live from our materials database.

What it means in practice

Flexural strength is the highest stress a material reaches when it is bent. Our hub lists it as “bending strength”. It matters because most real parts are bent far more often than they are pulled straight.

Key takeaways

  • Flexural strength is the peak stress a material reaches when bent; our hub calls it bending strength.
  • Most real parts are bent far more often than they are pulled straight.
  • Outer walls carry most bending load, so extra perimeters often beat extra infill.
  • Flexural values usually run higher than tensile ones, so never mix them across sheets.
Filaments81 MPatypical · range 5–540 · 185 materials
Resins75 MPatypical · range 7–400 · 136 materials
Powders56 MPatypical · range 37–110 · 7 materials

Think of:

  • Shelf brackets and cantilevered arms.
  • Clips, latches and levers.
  • Panels and lids that are pressed in the middle.
  • Tool handles and jig arms.

Tip

When a part bends, one face is stretched and the opposite face is squeezed. The highest stresses are at the outer surfaces. For a printed part, that means the outer walls carry most of the load. Adding perimeters often helps bending performance more than adding infill.

How it’s measured

A rectangular bar rests on two supports. A rounded nose pushes down in the middle (three-point bending) until the bar breaks or reaches a set strain.

  • Standards: ISO 178 (typically an 80 × 10 × 4 mm bar) and ASTM D790. See ASTM vs ISO.
  • Units: MPa.
  • When nothing breaks: tough or flexible materials may bend without breaking. ASTM D790 stops at 5% strain, and the sheet may then report the stress at that point rather than a true break.

How to read and compare it

  • It is usually higher than tensile strength for the same material. Only a thin layer at the surface sees peak stress, so there are fewer flaws in the danger zone. Do not compare a flexural number from one sheet with a tensile number from another.
  • Orientation. A bar printed flat bends across its layers differently from one printed on edge or upright. Sheets that state orientation are easier to trust. See print orientation: XY vs Z.
  • Break or yield. Check whether the value is at break, at yield, or at 5% strain. They are not the same thing.
  • Typical values. Leave a margin. See typical vs minimum values.
  • Continuous-fibre materials report very high values from specimens built to show off the fibre. Real parts reach them only where fibre is laid along the load.

Range in our catalog

  • All materials: 5–540 MPa (median 78 MPa, 346 materials)
  • Filaments: 5–540 MPa (median 81 MPa, 185 materials)
  • Resins: 7–400 MPa (median 75 MPa, 136 materials)
  • Standard materials: 22.9–125 MPa (median 70 MPa, 69 materials)
  • High-performance materials: 50–529.7 MPa (median 120 MPa, 48 materials)
Flexural strength of common filaments (MPa)
  1. PLA 2540.4–115
  2. PETG 1254–94.6
  3. ABS 1646.6–80
  4. PC 1263.4–144
  5. PA6 970–161
  6. PEI 1290–178
  7. PEEK 10100–145
  8. PEKK 795–178

Bar = lowest to highest, dot = median. 103 materials, live from our database.

Watch out

Filled and unfilled grades share each bar, and values may be at break, at yield or at 5% strain. Use the chart to rank, not to design.

Highest and lowest in our catalog

Highest overall

MaterialPolymerBending strength
Markforged Carbon Fiber—540 MPa
Markforged Carbon Fiber FR—540 MPa
Markforged Carbon Fiber HT-A—529.7 MPa
Markforged Carbon Fiber HT—439.5 MPa
Markforged HSHT Fiberglass—420 MPa

Highest among resins

MaterialPolymerBending strength
Formlabs Alumina 4N ResinAlumina400 MPa
Monocure3D Precise+Photopolymer186 MPa
Formlabs Premium Teeth ResinPhotopolymer155 MPa
Phrozen Ceramic ProPhotopolymer150.12 MPa
Formfutura High Performance Resin Rigid CeramicPhotopolymer150–170 MPa

Lowest overall

MaterialPolymerBending strength
Kexcelled THE K8 TPU 64DTPU5–10 MPa
Monocure3D GingivaPhotopolymer7 MPa
Formlabs Ceramic ResinPhotopolymer10.3 MPa
3D4Makers Facilan OrthoPolyester18 MPa
Formlabs BioMed Durable ResinPhotopolymer21 MPa

Find strong materials in the finder