A drawing says “hardness 110.” A datasheet says “R105.” A colleague says “ABS is about Shore D 78.”
Three numbers, one material, and none of them can be used the same way. That is the trap at the center of ABS plastic hardness: the value only means something when you attach the scale letter and the grade it came from. Strip those away and you can end up comparing an ABS reading to a polycarbonate value and getting an answer that is flatly wrong.
You probably already know ABS is hard enough for housings, tough enough for trim, and easy to machine and plate. What you need is the number that holds up on a drawing, and the logic behind why your grade reads where it does. This guide gives you ABS hardness on both scales, shows how general-purpose, high-impact, heat-resistant, glass-filled, and PC/ABS grades differ, explains the trade-off between toughness and hardness, and shows how to keep a validated hardness range stable lot to lot.
If you are new to the test methods behind these numbers, our complete guide to plastics hardness covers the full landscape. Here we stay on ABS.
What Is ABS Plastic Hardness?
ABS plastic hardness is its resistance to indentation under a defined load. The most common values are Rockwell R90–R110 for unfilled grades, with most general-purpose grades landing at R100–R110, and Shore D 70–80. ABS is harder than the polyolefins, softer than PC, POM, PA66, and PMMA, and it belongs to a family of grades that trade toughness against hardness.
That is the short answer. The rest of this article is the reasoning you need when the number is going onto a spec.
Hardness measures resistance to indentation, not strength or toughness
Hardness is an empirical surface test. It does not measure tensile strength, impact resistance, or scratch resistance, and a hard material can still crack under a drop. This matters for ABS more than most polymers because ABS is sold as an impact-toughness material. When a housing is specified for “high impact,” you are usually buying lower hardness, not higher.
Why ABS is quoted on the Rockwell R scale, not the M scale
ABS is an amorphous thermoplastic that is relatively soft compared to PC or POM, so it is tested on the Rockwell R scale, which uses a 1/2-inch (12.7 mm) steel ball under a 60 kgf major load. Harder polymers like polycarbonate and acetal use the M scale: a 1/4-inch ball under 100 kgf.
Same principle, different setup, and the results are not interchangeable. An ABS value of “R105” and a PC value of “M78” describe two different tests. Our Rockwell hardness of plastics article walks through every scale letter and the full procedure.
The test methods behind the numbers
Two standards govern the values you will see on datasheets:
- Rockwell R: ASTM D785 or ISO 2039-2, reported as “R” plus a number. MatWeb’s Rockwell hardness testing reference documents the loads, ball diameters, and dwell times behind each scale.
- Shore D: ASTM D2240 or ISO 868, reported as “Shore D” plus a number. See MatWeb’s Shore durometer testing reference for the spring-load geometry.
Both are indentation methods, and both are sensitive to thickness, dwell time, and temperature. Two labs testing the same grade can report numbers a few points apart, which is why a range, not a single figure, is the honest way to quote ABS hardness.
Specifying ABS and need a hardness value you can defend on a drawing? Request a quote for branded prime ABS with datasheets on the correct scale, COA documentation, and 25 kg minimum order.
ABS Hardness by Scale: Rockwell R and Shore D
Here is the ABS plastic hardness chart, sorted by grade. No single datasheet gives you this view, because each one covers a single product.
| Grade type | Rockwell R | Shore D | What it means |
|---|---|---|---|
| General purpose | R100–R110 | 75–80 | The default balance of hardness, gloss, and toughness |
| High impact | R90–R100 | 70–75 | More rubber, more toughness, lower hardness |
| Heat resistant | R105–R115 | 78–80 | Higher acrylonitrile, harder and more heat-tolerant |
| Glass / mineral filled | R110+ (E scale at high loadings) | 80+ | Filler raises hardness and stiffness |
| PC/ABS blend | Between ABS and PC | 75–82 | Approaches the PC side as PC content rises |
| Plating grade | R100–R110 | 75–80 | Bulk hardness similar; surface behavior decides the spec |
Treat these as starting points. The real value depends on the specific grade, its filler and rubber content, and the test conditions. Always verify against the datasheet for the grade you are buying.
Rockwell R for ABS: R90–R110 typical
Across common unfilled grades, ABS Rockwell hardness reads roughly R90–R110. High-impact grades sit at the soft end near R95; high-rigidity and high-gloss extrusion grades reach R110 and above. eFunda’s ABS medium-impact injection grade is listed at R102–R115. Real datasheet values cluster tightly in the middle: Chi Mei POLYLAC® D-190 at R105, Röchling SUSTAABS® at R102, LyondellBasell Diamond 3500LG at R104, and Ensinger TECARAN® ABS at R108.
Shore D for ABS: 70–80
Shore D is the scale processors, machinists, and sheet buyers reach for because it works on finished parts with minimal sample prep, and a handheld durometer gives a reading in seconds. ABS material hardness on this scale reads Shore D 70–80, with reported values around 74 (SUSTAABS®) and 78 (TECARAN® ABS). High-impact grades sit at the soft end near 70; filled and PC-blended grades push toward 80. If you want the mechanics of that scale, see the Shore hardness scale explained.
Never quote a bare number
The scale letter is part of the value. A drawing that says “hardness 110” with no letter cannot be inspected, and a comparison table that sets an ABS R-value against a PC M-value is invalid. Write “R105” or “Shore D 78,” and record the standard. It costs four characters and saves a rejected lot.
What Changes ABS Hardness (The Grade Trade-Off)
ABS is not one material. It is a family built on a two-phase structure: a styrene-acrylonitrile (SAN) matrix with grafted butadiene rubber particles dispersed through it. Every hardness value follows from how that structure is tuned. Our ABS polymer structure article covers the mechanism in full; here is what it means for hardness.
Five levers move an ABS hardness reading:
- Butadiene rubber content: more rubber raises impact toughness and lowers hardness. This is the single biggest swing in the family.
- Acrylonitrile content: more AN raises hardness, heat resistance, and chemical resistance.
- Fillers: glass fiber (GF10/GF20/GF30) and mineral fillers raise hardness and stiffness, and at high loadings move the material onto the Rockwell E scale, exactly as glass-filled nylons do.
- PC blending: ABS/PC and PC/ABS alloys raise hardness and toughness together, which is why they cost more.
- Moisture, regrind, and processing: absorbed moisture, blended regrind, and molding anisotropy all shift a reading, which is why two parts from two lots can disagree.
The first three levers explain the table above. High impact ABS hardness is lower simply because more rubber is present; glass filled ABS hardness is higher because the filler carries load the polymer alone cannot. Neither grade is better. They solve different problems, and the hardness value is how you tell them apart at incoming inspection.
ABS Hardness vs Other Plastics
ABS sits in the middle of the engineering thermoplastics. Always read the scale letter in this table, because PC and POM are quoted on the M scale, not the R scale.
| Material | Rockwell | Shore D | Note |
|---|---|---|---|
| HDPE | R60–R80 | 60–70 | Softer polyolefin |
| PP | R80–R100 | 70–75 | Softer polyolefin |
| ABS | R90–R110 | 70–80 | Impact-toughness family |
| PA66 (dry) | R119–R120 | 75–85 | Conditioned nylon reads lower |
| POM copolymer | M76–M80 | 80–85 | Different scale (M) |
| PC | M70–M80 | 75–88 | Different scale (M) |
| PMMA | M80–M100 | 80–90 | Harder, scratches less |
The pattern is simple: ABS is meaningfully harder than the polyolefins, and meaningfully softer than the engineering plastics that carry load or optical clarity. For the polymer-vs-polymer read on the two extremes, see our HDPE vs ABS comparison.
Is ABS harder than polycarbonate?
No. PC is harder on both scales, and the two Rockwell figures sit on different scales, so they cannot be lined up numerically. ABS is the lower-cost, easier-processing, better-flowing material; PC is tougher at impact, harder at the surface, and far more transparent.
If your decision is material selection rather than a single property, start with our polycarbonate vs ABS comparison. Covestro Makrolon® is the benchmark PC grade we stock if you need to evaluate both, see our PC resin.
Hardness vs Scratch Resistance in ABS
This is the distinction that decides whether a cosmetic part passes inspection. Bulk hardness is not surface scratch resistance. A material can resist indentation and still mar visibly under a fingernail or a shipping rub.
ABS has good, not exceptional, scratch resistance. Its high surface strength and gloss make it a strong choice for enclosures and trim, but a high-gloss molded surface will still show scratches. That is why visible ABS parts so often get a textured (haircell) finish, a hard coat, or paint.
The tests that actually quantify surface behavior are different from Rockwell and Shore:
- Pencil hardness: a scratch-resistance scale, commonly HB to H for uncoated ABS, higher with a cured coating.
- Taber abrasion (ASTM D1044 / D4060): measures wear haze over a set number of cycles.
This is also why plating-grade and paintable ABS grades exist. For those parts, surface behavior and adhesion drive the spec, and bulk hardness is secondary. Our ABS coating and plating guide covers the surface-treatment side, and the painting ABS plastic cluster covers finishes.
Branded ABS Grades and Hardness Baselines
The numbers in the tables above come from real, published datasheets. Prime brands set the benchmark, and knowing a few baseline values helps you sanity-check any ABS plastic hardness figure you are quoted. There is no valid hardness conversion between the R and M scales, so a quote only compares to your spec if it carries the same scale letter.
| Grade | Representative hardness |
|---|---|
| Chi Mei POLYLAC® D-190 | R105 |
| INEOS Styrolution Novodur® 440 | R112 |
| INEOS Styrolution Novodur® Xspray | R110 (paintable, enhanced post-paint scratch resistance) |
| Denka MALECCA™ K-510 | R112 (ISO) / R114 (ASTM) |
| Kumho HU-600 | R107 |
| Clarastic AN-490 | R109 |
| Röchling SUSTAABS® | R102 / Shore D 74 |
Two lessons sit in that table. First, prime ABS lands mostly between R102 and R114 once you leave the high-impact end. Second, the same grade can be reported two points apart depending on whether the lab used ISO 2039-2 or ASTM D785, so a small difference between two datasheets is not a red flag.
BASF Terluran®, INEOS Styrolution Lustran®/Novodur®, and Chi Mei POLYLAC® are the brands we stock and the ones your own drawings are most likely to name.
Sourcing Consistency: Why ABS Hardness Drift Signals a Resin Problem
Hardness is not just a design property. On ABS, it is one of the fastest QC checks you can run, and drift in it tells a story about what is actually in the bag.
Priya, an incoming-inspection lead at an appliance-components molder in Malaysia, watched Rockwell R readings from a new ABS supplier creep from R104 down to R97 over three lots. The parts still molded, so nobody flagged it at first. But the drop pointed to a higher-rubber, lower-grade resin being substituted for the grade on the PO.
A certificate-of-analysis check confirmed the MFI was off-spec too. Catching it at incoming inspection cost one pallet; catching it after assembly would have cost a warranty claim.
What a shifting hardness reading means
Lot-to-lot Rockwell drift on ABS usually points to one of four things: off-spec resin, regrind blended into virgin, a grade substitution, or a process shift at the molder. Because Rockwell R is fast, cheap, and non-destructive, it makes an excellent incoming and in-process check when you know the validated range for your grade.
What to verify on a COA
A COA is only useful if you read it. For ABS, confirm the grade designation, the MFI (ASTM D1238 / ISO 1133), the impact figure, and the lot number. Those four fields, cross-checked against the manufacturer’s datasheet, catch most substitutions before they reach the line.
How Yifuhui supplies hardness-consistent ABS
We hold branded prime ABS from BASF Terluran®, INEOS Styrolution Lustran®/Novodur®, and Chi Mei POLYLAC®, with traceable lots and full COA and MSDS documentation. Every batch is documented, so the hardness range you validated is the hardness range you reorder. Minimum order is 25 kg, terms are FOB Shanghai, and export documentation ships with the goods. Browse branded prime ABS resin or contact our technical team for a hardness datasheet on your grade.
Conclusion
ABS plastic hardness comes down to two numbers and one rule. The numbers: Rockwell R90–R110 and Shore D 70–80. The rule: a value without its scale letter and grade is not a spec.
Once you attach the grade, the family logic falls into place. More butadiene rubber buys toughness and gives up hardness, which is why high-impact grades read near R95. More acrylonitrile or filler buys hardness and heat resistance, while PC blending buys both at a higher cost.
Across all of it, ABS sits above the polyolefins and below PC, POM, and PA66, which is exactly the middle ground that makes it the default housing and trim material.
The last piece is consistency. Hardness drift lot to lot is an early signal of off-spec, regrind, or substituted resin, so the COA that travels with your order is as important as the datasheet behind it.
Specifying ABS for a part with a validated hardness, gloss, or plate-adhesion requirement? Request a quote for branded prime ABS (Terluran®, Lustran®/Novodur®, POLYLAC®), 25 kg minimum order, full COA documentation, FOB Shanghai, response within 24 hours.
Frequently Asked Questions
What is the hardness of ABS plastic?
ABS typically reads Rockwell R90–R110 (most general-purpose grades R100–R110) and Shore D 70–80. The exact value depends on the grade and its rubber, acrylonitrile, and filler content, so always quote the range with its scale letter rather than a single bare number.
Is ABS harder than polycarbonate?
No. PC is harder on both scales, and the two Rockwell values sit on different scales (ABS on R, PC on M), so they cannot be compared numerically. See our PC vs ABS comparison.
What is the Rockwell hardness of ABS?
ABS Rockwell hardness is roughly R90–R110, with most general-purpose grades between R100 and R110. High-impact grades read near R95 because of their higher rubber content; high-rigidity and extrusion grades reach R110 and above. Confirm the scale on the datasheet before comparing two grades.
Does glass-filled ABS have higher hardness?
Yes. Glass fiber and mineral fillers raise hardness and stiffness, and at higher loadings the material moves onto the Rockwell E scale, the same shift you see in glass-filled nylons.
What is the Shore D hardness of ABS?
Shore D 70–80. High-impact grades sit at the soft end near 70, while filled and PC-blended grades approach 80. Shore D is measured with a handheld durometer on finished parts, which makes it the practical field check when you cannot cut a Rockwell specimen.
Is ABS scratch resistant?
Moderately. Bulk hardness does not equal surface scratch resistance, so high-gloss ABS parts commonly need a textured finish, hard coat, or paint to hide handling marks.
Can you compare ABS hardness to PC or POM hardness?
Only if the scale letters match, and usually they do not. ABS is quoted on Rockwell R; PC and POM (acetal) resin are quoted on Rockwell M. Comparing the bare numbers is invalid for specification.
