A certified slip-resistant shoe is one an independent lab put on a tribometer machine, pressed into a contaminated floor, and measured—the whole shoe, not a scrap of rubber—until it hit the minimum grip score set by ASTM International’s standards for footwear testing.
Last updated: 08/07/2026
In the U.S., slip resistance in footwear is measured as a coefficient of friction (COF) using the ASTM F2913 test method, then rated under ASTM F3445-24. A non-slip boot or shoe earns one of two marks:
coefficient of friction of 0.40 or higher on dry and wet surfaces . Best for retail, hospitality, front-of-house, healthcare, light manufacturing—anywhere where water is the primary hazard.
Everything SR requires, plus 0.33 or higher on an oily/wet surface. All of our shoes are SRO-certified. Best for kitchens, food service & processing—anywhere oil hits the floor.
A shoe must pass SR before it can be tested and labeled SRO. “Slip-resistant” printed on a box without one of these marks is a claim, not a certification.
The Standards
ASTM F2913-24
ASTM F2913-24 is how grip is measured. Think of it as the rulebook for the machine. A finished shoe is clamped to an arm, set at the angle a real foot lands at, and dragged across a contaminated test floor under a fixed, repeatable force. The result is a slip coefficient of friction.
ASTM F3445
ASTM F3445 sets the bar and is the score a shoe needs to pass. It takes the COF numbers from an F2913 test and decides whether the shoe may be marked SR or SRO. This is the current revision — it replaced F3445-21.
Behind the machine
A tribometer measures how hard it is to make one surface slide across another. In footwear, that’s your outsole against a slippery floor. Here’s the whole test in four moves:
The finished shoe (not a swatch of outsole rubber) is secured to the test rig exactly as it would sit on a foot.
A standardized surface is coated with a water-and-surfactant solution for SR or oil for SRO. Also, we take it a step further by grease testing on Crisco® vegetable shortening.
The rig presses down with a set force and pulls the shoe sideways at a set speed, at the angle a real heel strikes the ground.
Resisting force divided by pressing force gives the coefficient of friction. Higher means more grip. 0.40 and up earns SR; 0.33 and up on oil adds SRO.
COF is a grip score between 0 and 1. Ice under a dress shoe is near 0.10. A certified SRO outsole on greasy tile still holds 0.33 or better.
Our Technology
Meeting the standard is easy. We build past it—in the outsole, the toe, and every test we run.
Most shoe brands buy their outsole material from an outside supplier, slap it on a shoe, and call it done. We make ours ourselves—we mix the rubber, build the molds that shape the tread, and test everything along the way. Before we even start making shoes, we test the rubber to make sure it's right. Then, every single day, we test the actual grip on the shoes coming off the line. If a mold starts wearing down and the grip starts slipping, we replace it, before it ever reaches your feet.
Our proprietary outsole features a sharp, geometric pattern that acts like squeegees, pushing away liquids and debris from the bottom of your shoes as you walk. It’s why every shoe with our outsole outperforms F2913 footwear testing on oil-covered ceramic tile. Learn more about how our outsoles get made, start to finish.
Our outsole tread patterns keep working with every step, actively clearing away debris before it can undercut your grip.
Technology availability varies by style
(low DIN = high durability)
We test for more than slip resistance. SFC anti-slip outsoles are rated using the DIN abrasion test—a durability benchmark most brands don’t publish. A lower score means higher durability, and our low DIN scores mean your slip resistance holds up long after a shoe’s first day on the floor. For even more durability, look for our 4HD™ abrasion-resistant outsoles.
For over a decade, we’ve partnered with independent biomechanics lab Heeluxe to test fit and comfort on every shoe. Each pair goes through Heeluxe’s SmartLast test—a foot-shaped device fitted with pressure sensors that identifies pressure points and fit issues before a shoe ever reaches your feet. The result: SFC shoes meet or exceed the industry average comfort score.
Beyond Slip Resistance
Slip resistance lives under the ASTM F3445 standard. Toe and add-on protections live under two others: ASTM F2413-24 for safety-toe styles & ASTM F2892-24 for soft-toe industrial styles. Either ASTM standard for footwear can carry the add-ons below.
Impact and compression protection.
A permanent plate between insole and outsole, rated to 270 lbf.
Secondary protection against incidental contact with live circuits.
Bleeds off static in sensitive environments.
Don’t confuse these two
EH protects against electrical shock. SD does the opposite, moving static into the ground. Never wear SD footwear near electrical hazards.
Common Questions
No non-skid shoe eliminates slip risk entirely. An ASTM rated outsole significantly lowers the odds on the surfaces it was tested for, but floor condition, contamination, and pace still matter.
Shoes that have actually been lab-tested—not just labeled "safety shoe" and called a day. ASTM International sets the rules, and a shoe has to pass real testing to earn ratings like slip resistance or toe protection.
Both mean a shoe passed slip testing. SR means it passed on wet and dry surfaces. SRO means it also passed on oily surfaces—a tougher test, and the one that matters most in kitchens and industrial spaces. All SFC shoes are SRO-certified.
Check the shoe’s label or product page for “SR” or “SRO” next to the code ASTM F3445-24. That number is your proof it’s real, and not just a marketing word.
OSHA doesn’t certify footwear. It requires employers to keep walking surfaces free of slip, trip and fall hazards, and to assess the workplace for hazards requiring PPE. Specifying footwear certified to ASTM F3445-24 SR or SRO is one common, documentable way to address the footwear part of that assessment.
Wet floors? Look for SR. Oily floors? Look for SRO.
In 2024, ASTM updated its footwear standards. F2913-24 and F3445-24 (the slip-resistance test and rating) were both revised, and F2413-24 and F2892-24 (toe protection standards) now include slip resistance too, so SR/SRO can be part of the same certification as toe protection, not a separate one.
For Safety & EHS Teams
Our corporate team helps safety directors match ASTM ratings to real job sites, standardize a program across locations, and document it.