Cargo Securement Calculator
How many straps or chains does it take to secure the load? Enter the cargo’s weight and length and the working load limit marked on your tiedowns — this checks both federal minimums (the length-based count rule and the 50 % working-load-limit rule) and gives you the greater of the two: the number you actually need.
Weight of the single article being secured.
The longest article on the deck.
The WLL stamped on each strap or chain tag — not its break strength. A 2″ ratchet strap is often around 1,600–1,700 lb WLL.
Minimum tiedowns for this load
Two rules, and you meet both
Federal cargo securement (FMCSA 49 CFR Part 393, the North American Cargo Securement Standard) sets two independent minimums for the number of tiedowns on an article that isn’t blocked against forward movement. You have to satisfy them both, so the number you actually need is whichever comes out higher.
The count rule (§393.110) is about length and weight: one tiedown for a short, light article; two once it’s heavy or longer than five feet; and a running add-on for anything over ten feet. The working-load-limit rule (§393.106) is about strength: the combined WLL of the tiedowns must be at least half the cargo weight. A short, dense, heavy piece often passes the count rule at two tiedowns but fails the WLL math — that’s the trap this tool catches.
Count says how many; WLL says how strong. The load is only legal when both are satisfied at once.
A worked example
Take a 4-foot machine base weighing 8,000 lb, secured with straps rated 1,667 lb WLL each. By the count rule it’s under five feet but over 1,100 lb, so it needs 2 tiedowns. But the 50 % rule needs at least 4,000 lb of aggregate WLL — and 4,000 ÷ 1,667 rounds up to 3 straps. Stop at two and you’re legal on count but 1,000 lb short on strength. The governing answer is 3.
The count-rule minimums (§393.110)
| Article (not blocked forward) | Min. tiedowns |
|---|---|
| ≤ 5 ft and ≤ 1,100 lb | 1 |
| ≤ 5 ft and > 1,100 lb | 2 |
| > 5 ft but ≤ 10 ft (any weight) | 2 |
| > 10 ft | 2 + 1 per extra 10 ft (or part) |
Metric equivalents from the Standard: 5 ft = 1.52 m, 10 ft = 3.04 m, 1,100 lb = 500 kg. Blocking, dunnage, or a headboard that stops forward movement can lower the count — this tool assumes the article is not blocked, the conservative case.
Where this stops being enough
Two simplifications keep this a quick check, not a full securement plan. First, it assumes each tiedown counts its full marked WLL — the direct case. An indirect tiedown that only passes over the load and anchors to the deck on both sides counts just 50 % of its WLL under §393.108, so you’d need proportionally more. Second, some commodities — metal coils, logs, pipe, vehicles, heavy machinery — have their own commodity-specific rules in §393.116–.136 that override these general ones. When in doubt, secure to the stricter figure and check the specific rule for your freight.