Shore hardness is the number that tells you how soft or firm a TPU print will be. Get it wrong and the part either doesn’t flex enough to work or is too soft to hold its shape. This guide covers the full printable range, how hardness changes your settings, and which applications each formulation is actually for.
Shore hardness is a standardised measurement of a material’s resistance to permanent indentation. A calibrated probe is pressed into the material under a fixed load for a fixed time. The depth of the indent determines the hardness number. Higher number means harder material.
There are two scales relevant to 3D printing. Shore A is for soft, flexible materials — rubbers, elastomers, and flexible filaments like TPU. Shore D is for harder plastics. Standard PLA and PETG are in the Shore D range. TPU lives entirely in Shore A.
A practical reference: a rubber band is around 25A. A typical car tyre is around 70A. A shoe sole is 55-75A depending on the type. A hard hat is 75-85A. Solid rigid plastic starts above 90A on the Shore A scale and moves into Shore D territory.
Not all TPU hardnesses are equally printable on consumer FDM equipment. The softer the filament, the harder it is to print reliably.
The practical printable range for direct drive FDM printers is 83A to 98A. Below 83A, the filament is soft enough that even a well-tuned direct drive extruder struggles to maintain consistent pressure without buckling. Above 98A, the material behaves more like a semi-rigid plastic than a flexible elastomer.
Bowden setups narrow this range further. On a Bowden system, 95A is marginal and requires extreme care. 87A and below is effectively not printable on Bowden equipment.
The most common commercial offerings fall at 83A, 87A, 95A, and 98A. Some brands offer additional hardnesses within this range. eSUN, Bambu, and Polymaker all produce 95A as their primary offering, with 87A available as a secondary option.
95A is where to start with TPU. It’s the most widely available hardness, the easiest to print, and the formulation that most phone case and functional flex STL files are designed around.
At 95A, thin walls hold their shape well enough to be handled but flex clearly under finger pressure. A 2mm wall at 95A bends but returns to shape. A 4mm wall at 95A is quite firm. Wall thickness gives you a significant range of effective stiffness within a single hardness.
Print settings at 95A: nozzle 220-235°C, bed 40-60°C, speed 20-30mm/s, retraction 0.5-1.5mm direct drive. These are the baseline settings covered in the main TPU guide. Start here before moving to softer formulations.
Best for: phone cases, cable management, snap clips, light-duty gaskets, grip overlays, flexible joints in assemblies.
87A is where the rubber-like quality becomes pronounced. Thin walls at 87A have genuine give and don’t hold their shape as firmly when released. The material compresses more readily under load and provides better grip and vibration absorption than 95A.
The trade-off is printability. 87A is noticeably harder to print than 95A on the same settings. The extra softness makes the filament more prone to buckling between the drive gear and the hot end, even on direct drive systems. The extrusion path from the drive gear to the melt zone needs to be as short as possible.
Settings adjustments from 95A: reduce speed to 15-20mm/s (this is the main adjustment), raise temperature 5-10°C to 230-240°C for better flow, reduce retraction to 0.3-1.0mm. The slower speed is non-negotiable — 87A at 25mm/s will produce inconsistent extrusion on most printers. Don’t try to match 95A speeds.
Best for: wearables and wristbands, anti-vibration pads, soft grips and handles, gaskets that need high compression, shoe insoles, over-mould type grip surfaces.
83A and softer formulations are genuinely rubber-like. A 2mm wall at 83A has minimal resistance. These hardnesses are best for applications where the material needs to deform significantly under light loads: wearables worn directly on skin, very compliant gaskets, and parts that need to wrap around irregular surfaces.
Printability at 83A and below is challenging. Direct drive is mandatory, speed needs to drop to 10-15mm/s, and even then results are inconsistent unless the printer has a well-tuned extruder with minimal filament path length. Printers with integrated extruder designs (where the drive gear is immediately adjacent to the hot end with no gap) handle this range best. The Bambu Lab printers with their tightly integrated extruder assemblies are among the best consumer options for sub-87A TPU.
Retraction at this hardness range is often best disabled entirely. The soft filament deforms under retraction pressure enough that the retraction move doesn’t actually pull the filament back meaningfully — it just compresses the softness in the path and creates a rebound that causes a blob on the next move.
Best for: medical-grade wearables, finger guards, very compliant seals, custom orthotics, swim goggle seals.
98A is the firmest end of the Shore A scale for FDM printing. Thin walls at 98A feel almost rigid. The flex is there under deliberate force but doesn’t happen under light handling. The primary benefit is impact absorption without the softness of lower hardnesses — the material deforms on sharp impact and absorbs energy rather than fracturing the way PLA does, but returns to its shape immediately.
Printability at 98A is close to standard PETG. Most PETG print profiles work with minor temperature adjustment. Speed can be higher than softer TPU at 40-50mm/s. Retraction behaves more normally at 1-2mm.
Best for: impact-resistant cases where standard PLA cracks but full flexibility isn’t needed, protective bumpers, tool handles that need to absorb drops, edge protectors.
| Hardness | Feel | Nozzle | Speed | Best For |
| 83A | Very soft, rubber-like | 230-240°C | 10-15mm/s | Wearables, compliant seals |
| 87A | Soft, pronounced give | 225-240°C | 15-20mm/s | Grips, vibration pads, gaskets |
| 95A | Firm flex, holds shape | 220-235°C | 20-30mm/s | Phone cases, snap clips, joints |
| 98A | Near-rigid, impact absorb | 225-240°C | 40-50mm/s | Bumpers, tool handles, edge guards |
eSUN produces TPU at 95A as their standard offering and 87A as a secondary option. Both run consistently at the settings documented here. If you’re starting out, 95A is the right first spool.
eSUN TPU is available through the eSUN Official Store.
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More material guides and print-ready models at orefly.com.