If there's one piece of equipment I tell every new flatbed driver not to cut corners on, it's chains. You can replace a tarp. You can replace a strap. But if a chain fails under 40,000 pounds of steel, you've got a problem money can't always fix. This page is the numbers: what each size of chain is rated for, how the DOT adds those ratings up, and which size to buy for the freight you haul.
The short versionWhich Chain to Buy
Buy 3/8" Grade 70 with clevis grab hooks, 20 feet long, and buy at least four. That's the everyday chain for steel coils, plate, structural, and pipe, rated 6,600 pounds per chain. Keep a pair of 1/2" Grade 70 (11,300 pounds each) on the trailer for heavy equipment and the biggest coils, with 1/2" binders to match. Skip 1/4" and 5/16" for flatbed work unless you're chaining light equipment on a pickup or gooseneck. Never buy chain that isn't stamped with its grade.
The federal tableChain Working Load Limit by Size and Grade
These are the working load limits (WLL) in pounds that the FMCSA assigns to unmarked or marked chain by size and grade, straight from 49 CFR §393.108. If your chain carries a manufacturer's tag with a different number, the tag governs; if it carries nothing, this table is what an inspector will use. Grade 70 is highlighted because it's the transport grade.
| Chain size | Grade 30 (proof coil) | Grade 43 (high test) | Grade 70 (transport) | Grade 80 (alloy) | Grade 100 (alloy) |
|---|---|---|---|---|---|
| 1/4" | 1,300 | 2,600 | 3,150 | 3,500 | 4,300 |
| 5/16" | 1,900 | 3,900 | 4,700 | 4,500 | 5,700 |
| 3/8" | 2,650 | 5,400 | 6,600 | 7,100 | 8,800 |
| 7/16" | 3,700 | 7,200 | 8,750 | — | — |
| 1/2" | 4,500 | 9,200 | 11,300 | 12,000 | 15,000 |
| 5/8" | 6,900 | 13,000 | 15,800 | 18,100 | 22,600 |
All figures in pounds, from the chain table in 49 CFR §393.108. A dash means the regulation lists no value for that size and grade.
Reading the tableWhat the Grades Mean
Grade 30 is proof coil, the general-purpose chain at the hardware store. Look at the numbers: 3/8" Grade 30 is 2,650 pounds, less than half of the same size in Grade 70. It has no business on a flatbed.
Grade 43 is high test. Stronger than proof coil, still a farm-and-logging chain. Some drivers run it because it's cheaper. The table shows what you give up: 5,400 versus 6,600 pounds at 3/8". That's a missing chain's worth of WLL across a five-chain load.
Grade 70 is transport chain, heat-treated carbon steel, and almost always that gold or yellow chromate finish. It was designed for cargo securement. Every link carries a 7, 70, or 700 stamped into it every few links. That stamp is what you're buying. No stamp, no trust.
Grade 80 and 100 are alloy lifting chains, rated for overhead lifting, and they cost accordingly. They're legal for tie-down and a shade stronger, but notice 5/16" Grade 80 is actually rated lower than 5/16" Grade 70 in the federal table (4,500 versus 4,700). Unless you already own alloy chain from rigging work, Grade 70 is the right money.
Just because a chain is heavy doesn't mean it's made for cargo securement. I've seen shiny, aluminum-looking chain hanging on store shelves that has no business on a flatbed. When drivers first get into flatbed they're buying everything at once and the temptation is to grab the cheapest chain that "looks about right." Buying the wrong chain isn't saving money. It's creating a safety hazard.
The mathThe DOT Securement Math: Aggregate WLL vs. Cargo Weight
Here's the part a lot of rookies never learn until an inspector explains it on the shoulder. The law isn't "throw a few chains on and go." Under 49 CFR §393.106(d), the aggregate working load limit of your tiedowns must be at least one-half the weight of the cargo. That's the number an inspector checks, and it's a WLL number, not a chain count.
The regulation also says how much of each chain counts toward that total, and this is where drivers get surprised:
- 100% of a chain's WLL counts when the chain goes from an anchor point on one side of the trailer, over or through the cargo, to an anchor point on the other side. That's a chain through the eye of a coil, or over the top of a bundle.
- 50% counts when the chain goes from the trailer to an anchor point on the cargo itself. That's every direct tiedown on a piece of equipment, hooked to the machine's frame.
- 50% also counts when the chain leaves the trailer, goes around the cargo, and comes back to the same side.
The whole tiedown counts at the WLL of its weakest part. Under §393.108(a), that's the chain, the hooks, the binder, or the anchor point, whichever is lowest. A 6,600-pound chain on a 5,400-pound binder is a 5,400-pound tiedown. Check the binder tag before you do the math, because the binder is usually the weak link.
Required aggregate WLL: 44,000 ÷ 2 = 22,000 lb.
Chains run through the eye from an anchor on one side to an anchor on the other count in full. With 3/8" Grade 70 at 6,600 lb each: four chains = 26,400 lb. Legal at four, assuming your binders are rated 6,600 or better. If your binders are tagged 5,400 lb, each tiedown is 5,400 and four chains = 21,600, which is short. You need five. That's how a binder tag costs you a chain.
The coil rule in §393.120 adds its own requirements on top of this (rolling prevention, one tiedown forward and one rearward through the eye, angles). I walk through all of it in my guide to how to secure a coil load.
Required aggregate WLL: 48,000 ÷ 2 = 24,000 lb.
Every chain hooks directly to the machine's frame, so each one counts at half its WLL. 3/8" Grade 70: 6,600 ÷ 2 = 3,300 lb per chain, and 24,000 ÷ 3,300 = 7.3, so eight chains. 1/2" Grade 70: 11,300 ÷ 2 = 5,650 per chain, and 24,000 ÷ 5,650 = 4.2, so five chains. That's the whole reason 1/2" chain exists on a flatbed: on equipment, half-inch does with five what three-eighths needs eight to do.
Then the second rule. Under §393.130, equipment over 10,000 pounds gets a tiedown at each of four corners at the least, and any bucket, boom, or attachment gets lowered to the deck and secured with its own tiedown. So the real count on that excavator is five chains on the frame plus one on the bucket, all 1/2".
Minimum countThe Length Rule Stacks on Top
Even when the WLL math says two chains are enough, §393.110 sets a floor by length. For an article that isn't blocked at the front: one tiedown if it's 5 feet or shorter and 1,100 pounds or lighter; two tiedowns if it's 5 feet or shorter and heavier than 1,100 pounds, or between 5 and 10 feet long; and for anything over 10 feet, two tiedowns for the first 10 feet plus one more for every 10 feet or fraction of it after that. A 40-foot bundle of structural steel is two plus three, so five tiedowns minimum, no matter how light it is. You run both rules and follow whichever calls for more.
Straps are legal for a lot of that bundled freight and a lot easier on painted steel, and I cover where the line falls in chains vs. straps. Lumber goes under a lumber tarp with straps, not chain; coils and machinery get chain, full stop.
Picks by sizeWhich Size to Buy, and What It's For
1/4" Grade 70: light equipment, pickups, and utility trailers
1/4" G703,150 lb WLLLight dutyThe smallest transport chain. Fine for a zero-turn mower, a small tractor, or an ATV on a landscape trailer; too light to matter on a flatbed. If a 3,150-pound tiedown covers your cargo math, this is the cheapest and lightest way to be legal.
Shop options on Amazon →5/16" Grade 70: skid steers, mini excavators, goosenecks
5/16" G704,700 lb WLLMedium dutyThe common size on hotshot and gooseneck trailers, and plenty for a skid steer or mini excavator when you run four corners. On equipment each chain counts at half (2,350 lb), so do the math before you assume four is enough. Most 5/16" binders are rated for 5/16" and 3/8" chain both, which makes this an easy first step.
Shop options on Amazon →3/8" Grade 70: the everyday flatbed chain
3/8" G706,600 lb WLL20 ft, clevis grab hooksThis is the chain to own. The single most common transport chain on flatbeds in this country and where you start if you haul general steel. 6,600 pounds per chain, clevis grab hooks on each end so you can shorten it and dial the length. I ran mine 16 to 20 feet, long enough to reach through a coil eye and around to the other rail, short enough to handle. Buy from a maker that stamps the grade in the link.
Shop options on Amazon →1/2" Grade 70: heavy equipment and the biggest coils
1/2" G7011,300 lb WLL20 ft, grab hooks, 1/2" bindersThe step up. When I hauled a big piece of equipment or an exceptionally heavy coil, this is what went on, with matching 1/2" binders. It's heavy to handle and it costs about twice what 3/8" does, but on equipment it cuts the chain count nearly in half. Half-inch chain on 3/8" binders is a 3/8" tiedown; buy the binders with the chain.
Shop options on Amazon →The weakest linkHooks and Binders Have to Match
A chain is only as good as what's on the end of it. Grab hooks let you shorten a chain to exactly the length you want; that's what I ran most of the time. Slip hooks have their place when the securement method calls for them. Either way the hook is rated for a chain size, and a hook rated for 5/16" chain on a 3/8" chain is a 5/16" tiedown. Same with binders: the tag on the binder gives its WLL, and that number, not the chain's, is the one you carry into the math if it's lower. Never mix mismatched equipment because it happens to fit.
Inspect firstInspect Every Chain Before It Goes on the Trailer
It takes a few seconds. I'm checking for stretched links, bent links, gouges, deep rust or corrosion, cracks, twisted chain, worn grab or slip hooks, and damaged latches where they apply. If something doesn't look right, that chain comes out of service. When an inspector rejects a damaged tiedown, its WLL drops to zero, and a load that penciled out as legal becomes a violation on the spot. A quick walk-around at the scale house is cheap; your truck GPS will tell you which one is open ahead, and it beats finding out at the inspection lane.
Chains wear out. They get dragged across concrete, scrape steel, soak in rain and road salt, get overloaded. I've retired plenty over the years and never regretted replacing one early. I'd rather buy another chain than explain why one failed.
Heavy equipmentThe Four-Corner Rule
Anything over 10,000 pounds gets chained at four corners at the least, restraining the machine forward, back, side to side, and down, and every chain goes to the frame, never to lift arms, the bucket, or an attachment. The bucket comes all the way down and gets its own tiedown. A skid steer is not four chains; it's four at the corners plus one on the lowered bucket. And before you roll, measure the load's height. A raised boom or arm can put you into a bridge.
FAQGrade 70 Chain Questions
What is the working load limit of 3/8 Grade 70 chain?
6,600 pounds per 49 CFR 393.108. That is the single most common transport chain on flatbeds. For comparison, 3/8 Grade 43 is 5,400 pounds and 3/8 Grade 80 is 7,100 pounds.
What is the working load limit of 1/2 Grade 70 transport chain?
11,300 pounds per 49 CFR 393.108. Half-inch Grade 70 is the step up for heavy equipment and the heaviest coils, and it needs binders and hooks rated to match.
How many chains do I need for a load?
Two rules apply and you follow whichever calls for more. First, the aggregate working load limit of your tiedowns must be at least half the cargo weight (49 CFR 393.106). A chain that goes over or through the cargo from one side of the trailer to the other counts its full WLL; a chain hooked directly to the cargo counts half. Second, 49 CFR 393.110 sets a minimum count by length: two tiedowns for the first 10 feet of an article and one more for every 10 feet or fraction after that, and equipment over 10,000 pounds gets a tiedown at each of four corners.
My Advice to Every New Flatbed Driver
Don't buy chain because it looks strong. Don't assume every chain in a hardware store is safe for cargo securement. Don't mix grades because they're "close enough." And never gamble with the equipment that's keeping thousands of pounds of steel on your trailer.
After twenty years on the road, one thing has never changed. The chain doesn't care how experienced you are. It either has the strength to do the job, or it doesn't. When your truck is rolling down the interstate, that chain is protecting your life, your livelihood, and every family sharing the road with you. That's not the place to cut corners.
Sources (read September 24, 2026):
- 49 CFR §393.108, Working load limits (chain table and the weakest-component rule) — Cornell LII and eCFR (figures read from the Cornell copy)
- 49 CFR §393.106(d), Aggregate working load limit — Cornell LII
- 49 CFR §393.110, Minimum number of tiedowns — Cornell LII
- 49 CFR §393.130, Heavy vehicles, equipment and machinery — eCFR
- FMCSA Driver's Handbook to Cargo Securement — fmcsa.dot.gov
This article shares practical experience and general product guidance; it is educational and is not legal advice. Working load limits and securement counts vary by size, grade, manufacturer, and load. Always verify the grade stamped on your own chain, match your hooks and binders, and confirm your securement meets 49 CFR Part 393 for your specific load. Some links are affiliate links; buying through them may support this site at no additional cost to you.