SFI Ratings Explained: Racing Suits, Gloves and Shoes for Track Driving

An SFI rating is the small black-and-white patch on a racing suit's left sleeve, and it's one of the first things a tech inspector checks once your events start requiring fire gear. The number after the slash tells you how much heat the material held back in a standardized lab test. It isn't the number of layers, and it isn't a promise of how long you'll be protected in a real fire.

This guide explains SFI ratings: what SFI is, how to read a 3.2A/1, /5 or /20 label, what SFI 3.3 means on gloves, shoes and underwear, and how SFI compares with FIA 8856. We also show what specific organizers actually require, quoted from their own rules, so you can buy the right level once.

What an SFI Rating Is (and Isn't)

The SFI Foundation describes itself as "a non-profit organization established to issue and administer standards for specialty/performance automotive and racing equipment." SFI notes that "Sanctioning bodies all over the world include SFI specs in their rulebooks and use them as minimum requirements."

Two points in SFI's own wording matter to buyers:

• The manufacturer certifies the product, not SFI. SFI Spec 3.2A says certification "is made by the product manufacturer and products are not certified, endorsed or approved by SFI under this program." The patch means the maker represents that the suit passed the required tests. Under the spec, SFI can also buy products commercially and audit them.
• It's a minimum. The spec calls its standards "minimum guidelines for construction and evaluation of products."

So an SFI patch tells you that a garment met a defined lab test. It doesn't tell you how a suit will perform in a specific crash or fire.

Reading the Label: 3.2A/1, /3, /5 and Up

SFI Spec 3.2A covers driver suits. Suits are graded by Thermal Protective Performance (TPP), a lab measurement that SFI describes as "the product of exposure heat flux and exposure time." The higher the TPP, the longer the material holds heat back.

Each SFI rating also maps to an approximate time before a second-degree burn, which SFI publishes. We show it here as SFI does, but treat it as a lab-based comparison between grades, not a guaranteed escape time.

Layers aren't the rating. SFI calls this "a common misunderstanding," explaining that "It is actually possible for driver suits with various numbers of layers to have the same performance rating." The spec itself says a suit's rating "is based on the thermal protection capability of the material regardless of the number of layers."

Other tests in 3.2A include flammability (each layer must self-extinguish in an average of 2.0 seconds or less, with no melting or dripping), thread heat resistance, zipper heat resistance and multiple-layer thermal shrinkage resistance. The rating also doesn't include underwear: "The use of underclothing is not considered in the rating of the suit."

SFI 3.3: Gloves, Shoes, Underwear and Hoods

Everything that isn't the suit falls under SFI Spec 3.3, Driver Accessories. It covers "gloves, underclothing, hoods, socks, shoes, boots, helmet supports, harness pads, arm restraints, helmet skirts, and sports bras."

Gloves are graded by the thermal protection of the top (back of hand). For grade 5 and above, SFI also requires the palm side to reach at least 40% of the top's required TPP and the finger sides (forchettes) at least 20%. A glove that misses those figures "shall be downgraded." The palm and finger sides can't be leather alone. There has to be an FR layer between any leather and your hand.

Shoes come in one grade, 3.3/5. SFI's spec list names only "Shoes (3.3/5)," and the spec requires a minimum TPP of 19 in the non-sole part of the shoe.

Underwear, hoods and socks need a minimum TPP of 6. SFI's suit article makes the case for them: "Fire resistant underwear should be worn with every type of driver suit, especially single layer suits because it will double the minimum protection time (+3 seconds)."

Arm restraints don't have to be fire resistant. SFI grades them on strength instead: each strap has to hold a 400 lb load for ten seconds.

SFI vs FIA 8856

FIA 8856 is the FIA's standard for racing clothing. Where SFI uses a manufacturer-certified patch, the FIA uses a homologation label. Both SCCA rule sets we checked accept either one, but they list different FIA years. SCCA's Race Experience driver-gear page (in the Road Racing section of scca.com) accepts suits with an "SFI 3.2A/1, SFI 3.4 or higher certification label or FIA 1986 Standard or FIA Standard 8856-2000 homologation label." SCCA Time Trials' Safety Level 2 and 3 rules list FIA 8856-1986, 8856-2000 and 8856-2018 alongside SFI.

When does one matter more than the other? Usually when a series is sanctioned by, or runs under, FIA rules, or when you race internationally. If your rulebook names only FIA 8856, an SFI-only suit won't meet it, and the reverse is also true. Read the exact wording, including the year of the standard.

What HPDE, Time Trial and Wheel-to-Wheel Organizers Require

Requirements depend on the organizer and the level you run at. These are the rules we read directly on each organizer's site in September 2026. They're examples, not universal rules, and they change, so check your event's current rules before you buy.

HPDE and track nights.

• NASA's 2026.1 HPDE/Time Trial tech form says "A Nomex suit is highly recommended." On that form it's a recommendation, not a requirement. NASA's competition gear rules are in its Club Codes and Regulations (CCR) and regional supplements, so if you race or run Time Trial with NASA, check the current CCR for your region.
• Track Night in America's rules say "The basics are close-toed shoes and a helmet are required," and that some tracks require long sleeves and long pants.

SCCA Time Trials (national events).

• Safety Level 1 (Sport, Tuner and Max, plus Unlimited cars on 200+ UTQG tires) has one clothing rule: "Shoes covering the entire foot shall be worn."
• Safety Levels 2 and 3 require an FIA 8856 or "SFI 3-2A/5 or higher" suit. SCCA adds that "Suits carrying SFI 3-2A/1 certification may be worn only with fire resistant underwear." Levels 2 and 3 also require FR socks, gloves "containing no holes," and shoes whose uppers "at a minimum, cover the instep."

SCCA Race Experience (Road Racing section).

• Suits must carry an SFI 3.2A/1 or higher or SFI 3.4 label, or an FIA 1986 or 8856-2000 label.
• FR underwear "shall be used but is optional" with SFI 3-2A/5 or higher or FIA suits.
• Gloves must be "leather and/or accepted fire-resistant material containing no holes."
• All gear must be "in good condition and free of defects, holes, cracks, frays, etc."
• The page points to Section 2.4 of SCCA's Race Experience rules. If you're entering SCCA wheel-to-wheel racing, check SCCA's current rulebook for your event.

Notice that SCCA's glove and shoe wording doesn't name an SFI grade. It names materials. SFI 3.3 gloves and shoes are an easy way to meet that wording, because they're tested to a published standard.

Layering, Fit and Care

SFI's own guidance is practical:

• Wear FR underwear. SFI says it matters most under single-layer suits, where it "will double the minimum protection time (+3 seconds)."
• Don't buy it tight. SFI warns that "A suit worn too tight will compress the air gaps and allow heat to reach the skin faster."
• Follow the care tag. SFI calls reading the care tag and following the manufacturer's instructions "absolutely essential."
• Keep it clean of fluids. SFI advises against wearing your suit while working on the car, because "Grease, fuel, oil, and even cleaning fluids can soak into the fabric and support the flames of a fire."
• Replace after a fire. SFI says: "If you are ever involved in a fire, discard your suit and get a new one."

When to replace gear comes down to condition and the label. SFI lists no recertification period for 3.2A/1, /3 and /5 suits or for 3.3 accessories. Suits rated /10 and higher must be inspected every five years by the certifying manufacturer, which then issues a new label. Separately, organizers can reject worn gear. SCCA's "free of defects, holes, cracks, frays" rule is an example.

Building a Kit by Budget

Entry kit for HPDE or Level 1 time trial. A RaceQuip SFI-1 single-layer jacket or suit and a pair of gloves go a long way, even where they're optional. We list RaceQuip's 1-layer SFI-1 glove at $59.95 and the 2-layer SFI-5 glove at $79.95. Add FR underwear under a single-layer suit.

Club racing or Level 2/3 time trial. Read your rulebook first. Under SCCA's Race Experience and Time Trials Level 2/3 rules, an SFI 3.2A/1 suit works only with FR underwear. An SFI 3.2A/5 suit, or an FIA suit of a year SCCA lists, makes underwear optional. Add FR socks, SFI 3.3 gloves and SFI 3.3/5 shoes. SCCA Time Trials Levels 2 and 3 also require a balaclava if you have a beard.

Harness and seat. If your class requires a harness, it has its own SFI spec, 16.1, and SFI lists a two-year recertification period for it. See our seat belts and harnesses and our harness installation guide.

Common Questions

What does SFI 3.2A/5 mean?

It means the suit's manufacturer certifies that it meets SFI Specification 3.2A (driver suits) at grade 5. Grade 5 requires a Thermal Protective Performance rating of at least 19 cal/cm². SFI's published conversion puts that at about 10 seconds to a second-degree burn, compared with 3 seconds for grade 1. It doesn't mean five layers. SFI says suits with different numbers of layers can earn the same SFI rating.

Do I need a fire suit for HPDE?

Usually not, but check your organizer. NASA's HPDE/Time Trial tech form says a Nomex suit is "highly recommended." Track Night in America requires close-toed shoes and a helmet, and says some tracks require long sleeves and long pants. SCCA Time Trials Safety Level 1 requires shoes that cover the entire foot. Many drivers wear an SFI-1 suit or jacket anyway because it's inexpensive protection. Read your event's supplemental regulations before assuming gear is optional.

Is SFI-1 enough for time trial?

It depends on the organizer and your level. At SCCA Time Trials Safety Level 1, no suit is required. At Levels 2 and 3, SCCA accepts SFI 3-2A/5 or higher or FIA 8856, and says SFI 3-2A/1 suits "may be worn only with fire resistant underwear." So a /1 suit can work at those levels if you wear FR underwear. Other organizers word this differently, so check your event's current rules.

Do SFI suits expire?

Not by date at the lower grades. SFI's spec list shows no recertification period for 3.2A/1, /3 and /5 suits or for 3.3 accessories. Suits rated /10 and higher must be inspected by the certifying manufacturer every five years and relabeled. That doesn't make old gear safe forever. SFI says to discard a suit after any fire, and organizers such as SCCA require gear free of holes, frays and defects. Replace gear that's damaged or soaked with fluids.

What is SFI 3.3 on gloves and shoes?

SFI 3.3 is the Driver Accessories spec. SFI's spec list shows gloves at grades 1, 5, 10, 15 and 20, with the SFI rating based on the thermal protection of the top of the glove. From grade 5 up, the palm and finger sides must also meet minimums. Shoes come in one grade, 3.3/5, with a minimum TPP of 19 in the non-sole area. Look for the SFI patch on the glove cuff and on each shoe. Some organizers, such as SCCA, specify materials rather than an SFI grade for gloves and shoes.

SFI vs FIA: which do I need?

Whichever your rulebook names. Both SCCA rule sets we checked accept either. SCCA's Race Experience gear page accepts SFI 3.2A/1 or higher, SFI 3.4, or FIA 1986 or 8856-2000 labels, and SCCA Time Trials Levels 2 and 3 list FIA 8856-1986, 8856-2000 and 8856-2018 alongside SFI. Series that run under FIA rules may require FIA homologation. Check the exact standard and year in your rulebook before you buy.