R ratings vs PTV: the complete UK guide
R9–R13 ratings and PTV are the two figures everyone quotes for slip resistance — but they measure different things, and only one is part of the current UK standard. Here’s how they relate, and which proves your floor is safe.
What R ratings are
R ratings (R9 to R13) come from a German ramp test, DIN 51130. An operator in oil-contaminated boots walks a tilting sample of the flooring until they slip, and the angle at which that happens gives the rating. It is a useful way for a manufacturer to classify a product — but it is a laboratory test, on a clean sample, using oil as the contaminant.
One thing worth knowing up front: DIN 51130 has been withdrawn and folded into the current European standard, BS EN 16165:2021. That standard does include a shod ramp test, but it reports an acceptance angle and does not define R ratings at all — nor the A/B/C barefoot classes. The R and A/B/C labels live on in product marketing, but they are no longer part of the UK and European slip standard.
| R rating | Ramp angle | Typically specified for |
|---|---|---|
| R9 | 6–10° | Dry internal areas only (offices, shops) |
| R10 | 10–19° | Areas with occasional moisture |
| R11 | 19–27° | Regularly wet areas, commercial kitchens, entrances |
| R12 | 27–35° | Wet and contaminated areas |
| R13 | >35° | Heavy, constant contamination (industrial, food) |
How R ratings and PTV differ
The two measure different things in different ways. An R rating is produced once, in a lab, on a sample, by the maker. A PTV comes from the pendulum, tested wet, and can be measured on the actual floor after it has been laid, grouted, cleaned and walked on.
There is another reason the two diverge. The HSE has reservations about the ramp tests, because their contaminants — oil for the shod test, soap solution for the barefoot test — aren’t representative of what is usually on a real floor, which is water. The pendulum, by contrast, is designed to reproduce the thin water film that causes most everyday slips.
The approximate R-to-PTV relationship
People often want to convert an R rating into a PTV. There is no official conversion — the UKSRG deliberately doesn’t publish one, because the tests measure different things under different contaminants. The figures below are the rough correspondences often cited in industry. They are fine for a sanity check, but they are not a substitute for testing the installed floor:
| R rating | Indicative wet PTV | Slip potential |
|---|---|---|
| R9 | Low | High risk if wet |
| R10 | ~25–34 | Moderate |
| R11 | ~36–45 | Low |
| R12 | ~45+ | Low / very low |
| R13 | High | Very low |
Barefoot wet areas (A/B/C)
Barefoot areas — showers, changing rooms, pool surrounds — were historically classified A, B or C under DIN 51097, a barefoot ramp test using a soap-solution contaminant. Like the R ratings, these classes are no longer part of BS EN 16165. For barefoot areas, the meaningful in-situ measure is a pendulum PTV taken with the barefoot Slider 55 (referred to as Slider 57 in BS EN 16165).
Which should you rely on?
For UK compliance, and for anything that might end in a dispute or an insurance claim, the PTV is the figure that carries weight. It is the measure HSE points to, it reflects the floor you actually have, and — unlike an R rating — it can be taken on the installed surface at any point in its life. An R rating is a reasonable way to specify a product up front; a pendulum PTV is how you demonstrate the finished floor is safe.
Frequently asked questions
Does an R11 rating mean a PTV of 36?
Roughly, R11 often corresponds to a wet PTV in the mid-30s to mid-40s — but it isn’t guaranteed and there is no official conversion. Installation, grouting, cleaning and wear all change the real floor, so the only way to be sure is to pendulum test the installed surface.
Are R ratings part of the current UK standard?
No. DIN 51130 (R ratings) and DIN 51097 (A/B/C) were withdrawn and folded into BS EN 16165, which reports a ramp angle rather than an R or A/B/C class. The labels continue to be used commercially, but they are no longer defined in the standard.
Which should I rely on for compliance?
The PTV from a pendulum test on the installed floor. It is the measure HSE points to and the one that reflects your actual floor in its actual condition.
Why doesn’t the R rating match my floor’s PTV?
Different test, different contaminant (oil versus water), and a clean factory sample versus your installed, grouted, cleaned and worn floor. All of those move the real-world result.
Specifying or signing off a floor?
Don’t rely on the sample rating alone — we’ll pendulum test the installed floor and give you a PTV you can stand behind.