Tie-Down & WLL Calculator
Work out the minimum number of tie-downs and the aggregate working load limit your load needs under the federal cargo securement rules (49 CFR 393.106 and 393.110).
1. Your load
2. The tie-downs you plan to use (optional)
"Direct" = runs from the trailer to the load (counts half its WLL). "Over the top" = goes over, around or through the load and back to the trailer (counts its full WLL).
Result
How the calculation works
Aggregate working load limit. The combined WLL of the tie-downs securing an article must be at least one-half the article's weight. A tie-down attached directly from the vehicle to the article counts for half of its WLL; one that passes over, around or through the article and attaches to the vehicle on both ends counts for its full WLL.
Minimum number of tie-downs for an article that is not blocked against forward movement:
- 1 tie-down — article 5 ft or shorter and 1,100 lbs or lighter
- 2 tie-downs — article 5 ft or shorter but heavier than 1,100 lbs, or longer than 5 ft up to 10 ft
- 2 tie-downs for the first 10 ft, plus 1 more for every additional 10 ft (or part of 10 ft) — article longer than 10 ft
If the article is blocked against forward movement by a headboard, bulkhead or other cargo, it needs at least one tie-down for every 10 ft of length (or part of 10 ft).
Commodity-specific rules can require more — for example heavy vehicles, equipment and machinery of 10,000 lbs or more need at least four tie-downs, plus separate securement of attachments such as booms and buckets.
Important: this calculator is a planning aid, not legal advice. Always check the current text of 49 CFR Part 393 Subpart I and any commodity-specific rules that apply, use the WLL marked on your equipment, and follow your company's securement procedures.