Which Filament Is Strongest? What Makers' Own Data Shows

What does "strong" mean on a data sheet?

A data sheet doesn't give one strength number. It gives several, and a material can lead on one and trail on another. These are the ones this guide compares:

Prusa Polymers spells out why the second row matters. Its Prusament PA11 sheet lists a "Tensile strength anisotropy coefficient" and explains that it "characterizes the ratio between tensile strength in the Z axis and in the XY axis. The higher the ratio (max. 1), the more even the tensile strength in every direction." Every table below shows both directions where the maker publishes them.

Why can't you rank filaments across brands?

It's tempting to line up the biggest numbers from four makers. The makers' own documents show why that doesn't work.

Different measurements under the same name. Bambu Lab, Polymaker and Overture report tensile strength under ISO 527 with X-Y and Z bars. Prusament reports "Tensile Yield Strength" under ISO 527-1 for "Horizontal" and "Vertical xz" bars, and gives its between-layer figure as "Interlayer Adhesion," measured by a "Prusa Polymers" method rather than an ISO one. Bambu's X-Y impact rows give two figures and mark only the second "(notched)," while its PETG Basic sheet gives one impact figure with no notch label. Overture publishes a Vicat softening point and no HDT at all.

Different test bars. Each maker prints its own specimens on its own settings:

Different treatment after printing. This is the biggest trap.

• Bambu Lab anneals most of its V3.0 specimens. The note under the specimen conditions on the PLA Basic and PLA Matte sheets says "All the specimens were annealed and dried at 55 °C for 8 h before testing." The PETG-CF note says 65 °C for 8 h. The ABS, ASA, PET-CF, PAHT-CF and PA6-CF notes say 80 °C for 12 h. The PETG Basic sheet lists only print settings and says "It's not recommended to anneal prints of PETG Basic."
• Polymaker's Fiberon sheets put the treatment in footnotes under each mechanical table. Under the "Dry status" table on the PA6-CF20, PA612-CF15 and PA12-CF10 sheets: "All specimens were annealed at 100°C for 16h." Under the "Wet status" table, the bars were also "immerged in water at 60°C for 48h prior to testing." The PET-CF17 sheet's note reads "All specimens were annealed at 120°C for 10h." The PolyLite, PolyMax and Polymaker PETG and ASA sheets have no annealing note for their specimens.
• Overture says on each sheet: "All specimens were conditioned at room temperature for 24h prior to testing."
• Prusament's sheets list slicer settings for the specimens and say nothing about annealing or conditioning.

Bambu Lab's sheets also warn that its values "are for design reference and comparison only." Polymaker says its typical values "are intended for reference and comparison purposes only," and Prusa Polymers says values "are significantly dependent on print settings, operator experiences, and surrounding conditions." Comparison, in each case, means within that maker's own testing. For two-brand head-to-heads, see Bambu ABS vs PolyLite ABS, Polymaker ASA vs Overture ASA and Prusament PLA vs PolyLite PLA.

Bambu Lab: the V3.0 data sheet family

All figures from Bambu Lab's V3.0 technical data sheets. Tensile and modulus: ISO 527. Notched Charpy: ISO 179. HDT: ISO 75 at 1.8 MPa. Bambu marks the PET-CF and PAHT-CF mechanical tables "Dry state."

The order changes with every column:

• Tensile X-Y: PA6-CF, then PAHT-CF, then PET-CF. PETG Basic is next at 51 MPa, ahead of ASA, PLA Basic, PETG-CF and ABS, whose ranges overlap. PLA Matte is lowest.
• Tensile Z: PA6-CF and PAHT-CF (48 and 47 MPa) again lead. PETG Basic and PET-CF share 35 MPa. PA6-CF's and PET-CF's Z figures are both under half their X-Y figures.
• Notched impact: PAHT-CF, ABS and ASA lead, from 22.8 down to 19.6 kJ/m². PET-CF and PLA Basic sit near the bottom, and PETG Basic has no notched figure to place.
• Stiffness: PET-CF, PA6-CF and PAHT-CF lead by a wide margin. PLA Basic lists more stiffness than ABS, with ASA and PETG-CF close behind it.
• Heat: PET-CF, PAHT-CF and PA6-CF are all above 160 °C. ASA and ABS follow, then PETG Basic and PETG-CF at 68 °C, then the two PLAs.

Two Bambu details are easy to miss. PETG Basic lists more tensile strength than ABS or ASA in both directions, but it was the one material tested without annealing, so its bars were treated differently from the rest of the table. And adding carbon fiber didn't lift every figure: PETG-CF lists less X-Y tensile strength and stiffness than PETG Basic. Our carbon fiber filament guide covers what the fibers change, and PLA-CF vs PETG-CF compares Bambu's two easiest CF grades.

Polymaker: PolyLite, PolyMax and Polymaker PETG

All figures from Polymaker's data sheets. Tensile and modulus: ISO 527, GB/T 1040. Notched Charpy: ISO 179, GB/T 1043. HDT: ISO 75 at 1.8 MPa. None of these sheets says its specimens were annealed. The "How to make specimens" box differs by group, so we've grouped the rows by it.

Within the PLA group, which shares one specimen recipe, the order flips depending on what you measure. PolyLite PLA lists the most tensile strength in both directions and the most stiffness, and the least notched impact. PolyMax PLA lists over ten times PolyLite PLA's notched impact figure, with less tensile strength and stiffness. PLA Pro sits between them. PolyLite PLA-CF lists the lowest strength between layers in the group, at 15.1 MPa.

The same pattern shows in the other groups. Polymaker PETG lists more tensile strength than PolyMax PETG; PolyMax PETG lists more than twice its notched impact and a higher HDT. PolyLite PC lists the highest tensile strength in both directions of any non-Fiberon sheet here, and one of the lowest notched figures. PolyMax PC lists less tensile strength and over five times the notched impact. Polymaker's polycarbonate guide covers the two PC grades.

The Polymaker ASA sheet adds a note: "Based on testing with Polymaker™ PolyLite ASA (SKU: PF01046)."

Polymaker Fiberon: annealed specimens

The Fiberon sheets test annealed bars, per the footnotes quoted above, so we've kept them in a separate table. These are the "Dry status" figures where a sheet gives dry and wet tables. Same ISO standards as above.

Fiberon PA6-CF20 leads every Polymaker sheet on X-Y tensile strength, stiffness and HDT. Between layers, its 54.0 MPa is level with PolyLite PC's 52.8 and PA12-CF10's 52.2 MPa once you allow for its ± 5.2 MPa spread. On notched impact it sits mid-table, below PolyMax PLA, PolyMax PC, PolyLite ABS, PLA Pro and PolyMax PETG.

Moisture changes the picture for the nylons. On the PA6-CF20 sheet's "Wet status" table, X-Y tensile strength drops to 54.7 MPa and notched impact rises to 35.6 kJ/m². Our nylon filament guide sets out the dry and wet figures for all three Fiberon nylons.

Prusament: one test recipe, one printer family

All figures from Prusa Polymers' Prusament technical datasheets. Tensile yield strength and modulus: ISO 527-1. Notched Charpy: ISO 179-1, "Edgewise direction of blow." HDT: ISO 75 at 1.80 MPa. Interlayer adhesion: Prusa Polymers' own method. Each sheet's specimens were printed on an Original Prusa i3 MK3-series printer with 2 perimeters, 100% rectilinear infill and no top or bottom layers. None mentions annealing.

Prusament's sheets don't call "vertical xz" a between-layer figure. The only figure they name for the bond between layers is interlayer adhesion. Read within Prusament:

• Tensile, horizontal: PC Blend Carbon Fiber and PC Blend lead (64 and 63 MPa), then PLA, PETG, and ASA level with PA11 Carbon Fiber.
• Interlayer adhesion: PC Blend Carbon Fiber, PC Blend and PA11 Carbon Fiber list the highest figures (23, 21 and 20 MPa), though their ranges overlap PETG's and PLA's. ASA lists the lowest, at 11 MPa.
• Notched impact: ASA, PC Blend, PC Blend Carbon Fiber and PA11 Carbon Fiber all list 12 kJ/m² horizontally. PETG lists 6. PLA's notched figure is "not applicable"; its unnotched figure is 13 ± 1 kJ/m², against "no break" for PETG and PC Blend.
• Stiffness: PC Blend Carbon Fiber and PA11 Carbon Fiber lead. PLA comes next, stiffer than PC Blend, ASA or PETG.
• Heat: PA11 Carbon Fiber at 152 °C, then PC Blend Carbon Fiber, PC Blend, ASA, PETG and PLA.

Prusa's newer Prusament PA11 sheet (1.0, updated 22-07-2026) used a Prusa CORE One+ with a 55 °C chamber, so we've kept it out of the table. It lists interlayer adhesion of 32 ± 1 MPa against a horizontal tensile yield strength of 38.3 ± 0.8 MPa, which matches the 0.84 anisotropy coefficient on the same sheet.

Overture: room-temperature-conditioned bars

All figures from Overture's technical data sheets. Tensile and modulus: ISO 527, GB/T 1040. Notched Charpy: ISO 179, GB/T 1043. Overture doesn't publish an HDT, so the heat column is its Vicat softening temperature (ISO 306, GB/T 1633), a different test. Every sheet says "All specimens were conditioned at room temperature for 24h prior to testing," at 100% infill.

Within Overture's range, PETG and PLA list the most X-Y tensile strength, level within PETG's ± 4.8 MPa spread, and PETG lists the most between layers. ASA lists by far the highest notched impact, 13.1 kJ/m², and the highest Vicat point. PLA lists the highest modulus. ABS lists the lowest strength, stiffness and impact of the four rigid materials. Overture labels its ASA mechanical table "Dry State."

Read the ABS row with care. Its sheet lists the same specimen print settings as the PLA sheet, 205 °C and a 40 °C plate, while recommending 245–265 °C and an 80–100 °C plate for printing ABS. We've reported the figures as printed. Ask Overture before relying on them.

The TPU sheet gives a different set of figures: a 100% modulus of 9.7 ± 1.0 MPa, elongation at break of 332.1 ± 15.9%, and a Shore hardness of "~95A." Our TPU hardness guide explains those numbers. For Overture's matte and silk PLA, see matte vs silk vs standard PLA.

Heat is its own kind of strength

The HDT columns above show how far apart materials sit in each maker's range, and they don't always follow tensile strength. Bambu's PETG Basic lists more tensile strength than its ABS or ASA but a lower HDT. Polymaker's PolyMax PETG lists less tensile strength than Polymaker PETG but a higher HDT.

HDT depends on the test load. That's why we've used one load, 1.8 MPa, in every table. For both loads, Vicat figures and each maker's annealing notes, see printed parts softening in heat. Bambu's sheets give heat figures from annealed bars for most materials, so a part you print and don't anneal isn't covered by those numbers. Our annealing guide covers which makers publish a cycle.

Which data sheet figure matters for your part?

Start with how the part will fail, then read that column within one maker.

• It will be pulled or bent along its layers. Read tensile X-Y and modulus. At Bambu Lab and Polymaker, carbon-fiber grades lead both. At Prusament, PC Blend Carbon Fiber leads.
• It could split between layers. Read tensile Z, or Prusament's interlayer adhesion. Print orientation matters here as much as material; our layer adhesion guide covers the print-side causes.
• It will be knocked or dropped. Read notched Charpy, and check the maker marks it notched. The leaders aren't the tensile leaders: Bambu's PAHT-CF, ABS and ASA; Polymaker's PolyMax PLA, PolyMax PC and PolyLite ABS; Overture's ASA.
• It must not flex. Read modulus. Bambu's PET-CF and Polymaker's Fiberon PA6-CF20 lead their makers' tables. At Polymaker and Prusament, standard PLA lists more stiffness than the same maker's PETG or ASA.
• It will be warm under load. Read HDT at the load you need, from the same maker.

If a part has to do two of these, pick the material that does acceptably on both in one maker's table, rather than the best on one. The PLA vs ABS, PLA vs ASA and PLA vs PLA+ guides work through common trade-offs, and ABS vs ABS+ covers what makers say their "plus" grades change.

Where the documents need care

• Overture ABS (V5.1) lists specimen print settings identical to its PLA sheet, below its own recommended ABS settings.
• Bambu PETG-CF (V3.0) says its specimens were "annealed and dried at 65 °C for 8 h," then suggests annealing models at "55 to 60 °C, and the time is 65 to 70 hours." The suggested time is far longer than any other Bambu sheet here gives (6 to 12 hours). Check with Bambu Lab before using that cycle.
• Bambu PETG Basic (V3.0) gives one X-Y impact figure, 34.2 ± 4.1 kJ/m², without saying whether the bar was notched, so we've left it out of the notched column.
• Bambu PLA Matte (V3.0) prints its notched impact figure, 6.3 ± 1.5, without a unit; the unnotched figure beside it is in kJ/m².
• Polymaker version numbers in file names don't always match the documents. The PolyLite PLA Pro and PolyLite ABS files are named V5.4 but headed V5.5, and the ASA file is named PolyLite ASA V5.4 but headed V6.0. We've used the version printed on each document.

Before you pick a "strong" filament

• Decide which kind of strength the part needs: along the layers, between them, against knocks, against flex, or in heat.
• Find the data sheet for the exact spool, not the material in general.
• Compare candidates from one maker, using that maker's tables.
• Check the standard and whether impact is marked notched.
• Read the specimen notes. Annealed, dried, wet and room-conditioned bars aren't the same test.
• Treat overlapping ± ranges as a tie.
• Check what the stronger material asks of your printer: nozzle, enclosure and drying needs come with it.

Ready to choose? The specialty filament shortlist covers ASA, nylon and PC grades, and the carbon fiber filament shortlist covers filled grades and the nozzles they need. For everyday parts, the PLA filament shortlist lists spools with their published maker data.

Specialty materials: what to check before you buy a spool ↗