ASTM F2413 Explained: Decoding the Safety-Toe Boot Marking (I/75, C/75, EH, Mt, PR, SD)

Short answer: the little rectangular stamp inside your boot tongue is the ASTM F2413 marking, and it reads top to bottom like a spec sheet. ASTM F2413-18 tells you the standard and the edition. M I/75 C/75 tells you it's a men's last, the toe cap survived a 75 ft-lbf impact, and it held up under 2,500 lbf of compression. Anything after that — EH, Mt, PR, Cd, SD — is an optional add-on the boot earned on top of the mandatory toe protection. This guide decodes every block of that stamp, with the actual force and voltage numbers behind each code, so you can look at a label and know exactly what the boot does and does not do.

One rule I follow in a safety category: every number here traces back to a published source — the ASTM F2413-11 specification text, Thorogood's rating breakdown, and the OSHA regulation itself. If a source doesn't state it, I don't state it. This is the explainer the boot roundups on this site point up to, so it's worth getting exactly right.

What ASTM F2413 actually is

ASTM F2413-11 is the "Standard Specification for Performance Requirements for Protective (Safety) Toe Cap Footwear." It replaced the former ANSI Z41 standard — which was withdrawn in 2005 — and it covers the minimum design, performance, testing, and classification requirements for footwear meant to protect against workplace hazards. (The number after the dash is the edition year: F2413-11 is the 2011 edition, F2413-18 is the 2018 edition.)

Here's the part most people miss. A boot doesn't get to wear any of the fancy add-on codes unless it first passes the two mandatory sections: Section 5.1, Impact Resistant Footwear, and Section 5.2, Compression Resistant Footwear. Metatarsal, conductive, electrical hazard, static dissipative, and puncture resistance are all optional add-ons — and per the spec, they can only be claimed after the base impact and compression requirements are met. So when you see M I/75 C/75 EH, the EH is riding on top of a toe cap that already passed impact and compression. No I/C, no add-ons. (Source: the UW-hosted ASTM F2413-11 specification.)

Where the marking lives, and how to read the stamp

The ASTM F2413 marking is stamped on one shoe of each pair — on the tongue, gusset, shaft, or quarter lining — enclosed in a rectangular border. The spec recommends a four-line format; line four only gets used when more than three sections of the standard apply. A worked example straight out of the spec:

One thing the spec is blunt about: altering the footwear after manufacture — replacing or adding footbeds or inserts — could cause failure of any or all parts of the standard and invalidates the safety marking. So that aftermarket insole you slipped in for arch support? Technically, it can void the certification on the label. (Source: ASTM F2413-11 spec text.)

Line 2: impact (I) and compression (C) — the mandatory core

This is the part of the marking every safety boot carries, because it's the part the standard requires. The number — 75, 50, or 30 — maps to a specific force level. Per the spec: compression ratings of 75 / 50 / 30 equal 2,500 / 1,750 / 1,000 pounds of compression respectively. On the impact side, I/75 means the toe cap was tested at a 75 ft-lbf impact; C/75 means it was tested at 2,500 lbf of compression.

But passing isn't just "the cap didn't break." The standard sets a clearance the cap has to maintain over your toes after the hit:

So I/75 C/75 isn't marketing — it's a measured outcome: after a 75 ft-lbf drop and a 2,500 lbf squeeze, there's still at least half an inch of room between the inside of the cap and your toes. Class 75 is the top protection tier; class 50 (1,750 lbf compression) is a lower tier. Most American work boots are built to I/75 C/75. (Sources: ASTM F2413-11 spec; Thorogood rating breakdown.)

Line 3: the optional add-on codes (EH, Mt, PR, Cd, SD, and more)

Everything after the I/C block is optional and only valid once the toe passed impact and compression. Here's every code you're likely to see, with the actual threshold behind it.

EH — Electrical Hazard

EH footwear has non-conductive, electric-shock-resistant soles and heels that provide a secondary source of protection against incidental contact with live circuits. The test: the boot must withstand 18,000 volts (RMS) at 60 Hz for one minute with no current flow or leakage in excess of 1.0 milliampere — under dry conditions. Read that last part twice. EH is a backup for incidental contact, it's a dry-condition rating, and protection drops when the boot is wet or worn. It does not replace de-energizing, insulated gloves, or lockout/tagout. I cover this one in depth in the EH-rated boots explainer. (Source: ASTM F2413-11 spec.)

Mt — Metatarsal protection

Mt guards protect the metatarsal bones at the top of the foot from drop hazards — the area between your toes and your ankle that a steel toe does nothing for. Mt/75 footwear retains a 1.0-inch clearance for men's (0.937 in for women's) after a 75 ft-lbf (101.7 J) impact. If you work around dropped pipe, plate, or heavy tooling that can land across the instep, this is the code you want — and most boots don't carry it. (Sources: ASTM F2413-11 spec; Thorogood breakdown. For picks, see best metatarsal-guard boots.)

PR — Puncture Resistant

PR footwear has a puncture-resistant plate that is an integral, permanent part of the boot, sitting between the insole and outsole — not a removable insert. To earn PR, the footwear must show no cracking after 1.5 million flexes and have a minimum puncture resistance of 270 pounds (1,200 N). Any metal plate also has to pass ASTM B117 salt-spray corrosion testing — no corrosion after 24 hours in a 5% salt solution. (Sources: ASTM F2413-11 spec; Thorogood, which states PR as puncture-resisting through the sole at a 1,200 N / 270 lbf load.)

Cd — Conductive

Conductive footwear is the deliberate opposite of EH. It's designed to reduce static build-up and the chance of igniting explosives or volatile chemicals by transferring static charge to ground. Its electrical resistance must fall between zero and 500,000 ohms. You'd see this in explosives handling or certain munitions work — never wear Cd where electric-shock hazard is the concern. (Source: ASTM F2413-11 spec.)

SD — Static Dissipative

SD footwear threads the needle between EH and Cd: it keeps resistance high enough to reduce the chance of electric shock while still bleeding off static. The spec sets a lower limit of 10^6 ohms (1,000,000 / 1 megohm) and an upper limit of 10^8 ohms (100,000,000 / 100 megohms). This is the electronics-and-cleanroom rating — you want static gone, but you don't want a dead short to ground. (Source: ASTM F2413-11 spec.)

DI and chainsaw cut — the less common ones

The standard also covers dielectric insulation (DI) and chainsaw cut resistance among the optional performance categories a boot can be certified for, in addition to the mandatory impact and compression. You'll see these on specialized footwear (utility, forestry); most general work boots don't carry them. (Source: ASTM F2413-11 spec.)

Putting it together: a full marking, decoded

Take a label that reads ASTM F2413-18 M I/75 C/75 EH. Here's every block:

Five blocks, five facts. Nothing in that line is decorative — each piece is a tested threshold. And nothing about EH on the end changes the toe rating: the I/75 C/75 is still the mandatory core. (Sources: ASTM F2413-11 spec; Thorogood rating breakdown.)

Does OSHA require ASTM F2413 boots?

OSHA requires protective footwear, and it points to ASTM to define what "protective" means — but it doesn't write the boot spec itself. The regulation, OSHA 29 CFR 1910.136(a), reads:

"The employer shall ensure that each affected employee uses protective footwear when working in areas where there is a danger of foot injuries due to falling or rolling objects, or objects piercing the sole, or when the use of protective footwear will protect the affected employee from an electrical hazard, such as a static-discharge or electric-shock hazard, that remains after the employer takes other necessary protective measures."

For the "what counts as protective" part, 1910.136 accepts footwear that complies with consensus standards including ASTM F-2412-2005 and ASTM F-2413-2005, or ANSI Z41-1999, or ANSI Z41-1991. Footwear the employer can demonstrate to be equally effective is also permitted. In plain terms: OSHA incorporates the ASTM standard by reference, so a boot marked to F2413 satisfies the footwear requirement where your job hazard analysis calls for it. (Source: osha.gov, 29 CFR 1910.136.)

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