Best Filament for Phone Cases: TPU Shore Hardness and Grip

Why TPU Is the Go-To Material for 3D Printed Phone Cases

Rigid filaments like PLA and PETG shatter on drop impact — their high tensile modulus means the energy has nowhere to go except into cracking the print. TPU's elastomeric nature lets it deform and spring back, absorbing impact energy and protecting the phone inside.

The key trade-off is between flexibility and structural integrity. A phone case must be rigid enough to stay in place on the phone and protect corners, yet flexible enough to install easily and dampen drops. Shore hardness — the A-scale number stamped on every TPU filament spool — is the single most important property to get right.

From the Filabase database of 109 TPU materials, three distinct tiers emerge for phone case use: soft (≤85A), medium (90–95A), and hard (≥98A). Each tier has different strengths and weaknesses for this application.

Understanding Shore Hardness for Phone Cases

Shore A hardness is measured by pressing a standard indenter into the material. A lower number means the material deforms more easily under the indenter — and under impact. The scale is roughly:

• ≤85A: Very soft and rubbery — more like a silicone-feel case. Maximum flexibility and grip but struggles to hold precise geometry.
• 90–95A: The phone case sweet spot — holds shape, snaps onto the phone, provides good corner protection, and still flexes enough to absorb drops.
• ≥98A: Near-rigid with limited flex — prints well and looks tidy, but provides less cushioning than softer grades on corner drops.

Most commercial silicone phone cases measure around 40–50A. OEM hard plastic cases are effectively off the A scale. A 3D printed TPU 95A case sits somewhere between these two — it's the closest you can get to a commercial "hard case with flex" using a desktop printer.

95A: Best All-Around Choice for Phone Cases

TPU 95A-range filaments dominate phone case printing for good reason. They are stiff enough to protect corners and maintain exact port cutout geometry, while flexible enough to flex during snap-on installation and absorb drop energy.

From our database of 34 Medium (90–95A) TPU filaments with quantified properties:

• Tensile strength: 12.5–44.2 MPa range (Bambu Lab TPU 90A at 12.5 MPa; BASF Ultrafuse TPU 95A at 44.2 MPa)
• Elongation at break: 300–800% — significant stretch before failure
• Typical density: 1.20–1.27 g/cm³
• Print temp: 200–250°C depending on brand

Notable 95A options from our database:

• BASF Ultrafuse TPU 95A — 44.2 MPa tensile, 661% elongation. Industrial-grade consistency.
• eSUN TPU-95A — 35 MPa tensile, 800% elongation. One of the highest elongation values in the 95A tier.
• Elegoo TPU 95A — 34 MPa tensile, 680% elongation, impact strength 124.8. Widely available and well-documented.
• Prusament TPU 95A — 41 MPa tensile strength. High-quality European option with excellent dimensional accuracy.
• Spectrum The Filament TPU 95A — 32 MPa tensile, 350% elongation. Good stiffness-to-flex balance for structured cases.

90A: Better Grip and Drop Absorption

If your primary goal is grip texture and drop protection over a slick, hard-case feel, TPU 90A is worth considering. The slightly lower hardness increases surface friction, gives the case a grippier feel in the hand, and allows more deformation on corner impacts before transmitting force to the phone.

From our database:

• Bambu Lab TPU 90A — 12.5 MPa tensile, 650% elongation, impact strength 124.2. Designed for AMS compatibility.
• Eryone TPU 90A — 23.7 MPa tensile, 573.9% elongation.
• FormFutura Python Flex TPU 90A — 35 MPa tensile, 500% elongation.
• Spectrum S-Flex 90A — 35 MPa tensile, 500% elongation, density 1.22 g/cm³.

The trade-off: 90A cases may deform slightly more under sustained pressure (e.g., sitting on the phone in a pocket). For most daily use, this is negligible, but if you want the case to hold a very precise, thin profile, 95A is safer.

85A and Below: Maximum Grip, Minimum Structure

Soft TPU (≤85A) produces the grippiest, most cushioning cases, but controlling print geometry is harder. The material tends to ooze more and fine details — camera cutouts, button covers, raised grip textures — are harder to achieve cleanly at this hardness.

Key 85A materials in our database:

• BASF Ultrafuse TPU 85A — 34 MPa tensile, 600% elongation. Surprisingly high tensile for its softness tier.
• Bambu Lab TPU 85A — 12 MPa tensile, 700% elongation, impact strength 124.3. Very soft feel.
• Siraya Tech Flex TPU 85A — 24 MPa tensile, 580% elongation.
• Spectrum S-Flex 85A — 40 MPa tensile, 650% elongation, density 1.11 g/cm³. One of the highest tensile values in the soft tier.
• colorFabb TPU 85A — 30 MPa tensile, 560% elongation, flexural modulus only 23 MPa (very soft feel).
• 3DXTech 3DXFLEX TPU 85A — 4 MPa tensile, 660% elongation. Extremely soft — almost gel-like. Use only for maximum cushion applications.

If you want a silicone-like feel on your phone case, 82–85A is the right range. For anything that needs to hold its shape, print clean overhangs, or maintain port alignment, stay at 90A or above.

Grip Texture Design: How to Get Grip Without Going Softer

Shore hardness isn't the only way to add grip. Surface texture design can increase effective friction even on a 95A print. From a materials and printing standpoint:

• Matte TPU variants like Fiberlogy MattFlex 40D (30 MPa tensile, 600% elongation) have a matte surface that grips better than glossy finishes without going to a softer hardness.
• Print orientation matters: Layer lines printed perpendicular to the grip surface create micro-texture that increases friction. Printing the back face vertically (with layer lines running across the width) produces a ribbed texture in the Z-direction.
• Infill patterns: Low infill (15–25%) with a gyroid pattern adds compliance to the case structure while using less material, effectively creating a softer effective hardness than the raw Shore A number suggests.
• Geometry: Raised ridges, dimples, or honeycomb patterns on the back surface add grip by increasing surface contact variation — independent of material softness.

Printability Considerations for Phone Cases

Phone cases have tight tolerances — a 0.5 mm error on a port cutout means the USB-C cable doesn't fit. TPU printability depends heavily on Shore hardness:

For Bowden extruder setups, 95A is strongly recommended. Softer grades tend to buckle in the Bowden tube, causing inconsistent extrusion and blobs. If you have a direct drive extruder (Bambu, Prusa MK4, Voron, Ender 3 with upgrade), 90A becomes practical, and 85A is achievable with careful retraction tuning.

Recommended print settings for phone cases:

• Print speed: 20–40 mm/s for 85–90A; up to 60–80 mm/s for 95A (brand-dependent — Bambu Lab TPU 95A HF is rated for high-speed printing)
• Retraction: Minimal — 0.5–2 mm for direct drive, disabled or very short for Bowden
• Cooling: Moderate fan (30–50%) helps bridge integrity without causing delamination
• Wall count: 3–4 walls for structural rigidity; thin walls on soft TPU will flex permanently
• Bed adhesion: PEI spring steel or blue tape; TPU sticks aggressively to glass if overheated

High-Speed TPU Options

If print time matters, several manufacturers offer high-flow TPU variants specifically designed for faster printing:

• Bambu Lab TPU 95A HF — 27.3 MPa tensile, 650% elongation, rated for high-flow printing. Impact strength 123.2.
• Polymaker PolyFlex TPU95-HF — 23.11 MPa tensile, 462.3% elongation. Optimized for high-speed FDM with reduced stringing.
• Elegoo Rapid TPU 95A — 13 MPa tensile, 500% elongation. Budget-accessible high-speed option.
• Overture High Speed TPU — 27.1 MPa tensile, 301.8% elongation. Lower elongation but good shape stability.

Note that high-speed TPU filaments often sacrifice some elongation for better flow characteristics. For phone cases where drop protection matters, check the elongation spec — values below 300% reduce the energy absorption during impact.

98A+: When You Want a Hard Case Feel

Hard TPU (≥98A) produces cases that feel closer to polycarbonate than rubber. They provide good corner protection through rigidity rather than energy absorption, print cleanly with high dimensional accuracy, and don't pick up lint the way soft TPU does.

• Spectrum S-Flex 98A — 55 MPa tensile, 510% elongation, density 1.09 g/cm³. Highest tensile in the hard tier.
• AzureFilm TPU 98A — 45 MPa tensile, 350% elongation.
• Fillamentum Flexfill TPU 98A — 318% elongation, density 1.23 g/cm³.

The downside: a 98A case may crack on a high-energy corner drop rather than deforming and springing back. For phones with lighter bodies (under 200g), this may never be an issue. For heavier, larger-format phones, the softer grades absorb drops more reliably.

Side-by-Side: Phone Case TPU Comparison

Bottom Line: Which Shore Hardness Should You Choose?

• For most people: TPU 95A. It prints reliably, holds port cutout geometry, snaps on and off cleanly, and provides adequate drop protection. BASF Ultrafuse TPU 95A (44.2 MPa, 661% elongation) and eSUN TPU-95A (35 MPa, 800% elongation) are standout options from our data.
• For grip-focused builds: TPU 90A. If you often hold your phone while moving and value in-hand security over a sleek look, 90A adds meaningful grip without sacrificing printability on direct drive machines.
• For silicone feel: TPU 85A. Only go here if you want that soft, rubbery texture and have a direct drive extruder. Spectrum S-Flex 85A (40 MPa tensile) punches above its hardness class in strength.
• For hard-case aesthetic: TPU 98A. Spectrum S-Flex 98A (55 MPa tensile) is the strongest in our database for this tier — but understand you're trading cushioning for rigidity.

For more on how these hardness tiers compare across all use cases, see TPU 85A vs 90A vs 95A Shore Hardness: Which Flexibility Do You Need? and Hard TPU 95A vs Flexible TPU 83A: When to Use Each.