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Anchor Cargo Path
Commodity-specific rules can be stricter than this general screen.
Use documented or measured load weight, not vehicle gross weight unless the whole load is one article group.
Measure the secured article or article group along the deck.
Blocking changes the length count; it does not remove the aggregate WLL requirement.
The diagram changes with this routing choice; mixed paths should be screened separately or with an approved custom factor.
Confirm the actual material, grade, marking, connectors, tensioner, and anchor before use.
A lower component, tensioner, connector, or anchor rating must be entered in Advanced.
The range offers 1–20 for quick comparison; the exact field accepts up to 100.
tie-downs
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The neutral blank default applies no reduction; field inspection must still identify the actual weakest component.
The neutral default is 0%.
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The neutral custom-path starting value is 100%.
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The neutral default is 100%; lower values are a repo-authored conservative screen, not a regulatory angle formula.
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Securement plan
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Calculation method:
The same values drive the summary, comparison, chart, and exports.
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The chart renderer is unavailable. The same capacity values remain available in the securement plan.

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Inspection guide
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This numerical screen is not a legal certificate or field approval. Apply the stricter commodity-specific rule, manufacturer instruction, carrier policy, and local requirement.

Trailer Payload Capacity Calculator Calculate trailer cargo capacity from GVWR and measured weight, then compare reserve, axle and tire limits to find the controlling margin.
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A cargo securement plan must satisfy more than a strap count. The combined working load limit (WLL) has to meet the required share of cargo weight, the number of tie-downs has to satisfy length rules, and every strap, chain, tensioner, connector, and anchor has to be suitable and in serviceable condition.

WLL is the rated load used for securement planning. It is not breaking strength, and a higher breaking-strength claim does not replace a marked or table WLL. Under the represented U.S. federal rules, the WLL of a complete tiedown is limited by its weakest component or its anchor point, whichever is lower.

Indirect, opposite-side path
A tiedown passes over, through, or around the cargo and reaches an anchor on the other side; its full effective WLL is counted.
Direct path
A tiedown runs from a vehicle anchor to a cargo anchor; one-half of its effective WLL is counted.
Same-side return
A tiedown goes over or around the cargo and returns to the same side; one-half of its effective WLL is counted.
Blocking
A headerboard, bulkhead, other secured cargo, or an appropriate device prevents forward movement. Blocking changes the length count but not the aggregate-WLL requirement.

Article length creates a separate floor. An unblocked article up to 5 ft and no more than 1,100 lb needs at least one tiedown; heavier short articles and articles over 5 ft through 10 ft need at least two. Beyond 10 ft, another tiedown is required for each additional 10 ft or fraction. A properly blocked article needs at least one per 10 ft or fraction.

Commodity-specific rules can be stricter than the general rule. Rolling cargo needs chocks, wedges, a cradle, or equivalent restraint against rolling. Heavy vehicles and equipment at 10,000 lb or more have their own securement requirements. Logs, dressed lumber, metal coils, paper rolls, concrete pipe, automobiles, and several other cargo types also have dedicated provisions.

A numerical margin cannot detect cuts, burns, knots, damaged stitching, bent hardware, poor anchor geometry, edge abrasion, loose tension after settling, or an unsuitable securement method. Treat capacity arithmetic as one pre-trip check, followed by physical inspection and the rules that apply to the actual vehicle, route, and commodity.

How to Use This Tool:

Screen one article or one article group with a single securement path. Mixed paths should be checked separately unless an approved counted-WLL factor is available.

  1. Choose Cargo profile, then enter documented Cargo weight and the secured Cargo length.
  2. Select whether forward movement is blocked and choose the actual Tie-down path. The path changes how much of each tiedown's WLL counts.
  3. Choose a marked or table WLL source and confirm Marked or table WLL. In Advanced, enter any lower connector, tensioner, component, or anchor WLL so the weakest value controls.
  4. Enter Planned tie-downs. Add a planning reserve or conservative service factor only when those extra reductions are part of your plan; they are not substitutes for a legal or engineering requirement.
  5. Review Required tie-downs, counted WLL per tiedown, capacity margin, and the controlling rule. Stop if the count or margin fails, then inspect the actual equipment and commodity-specific requirements before transport.

Interpreting Results:

Required tie-downs is the largest of the capacity count, length count, and any heavy-equipment floor represented by the selected profile. A plan passes only when its tie-down count reaches that requirement and its aggregate counted WLL reaches the planning target.

  • A positive Capacity margin is spare modeled WLL above the target. It does not certify strap condition, anchor strength, tension, friction, or load stability.
  • Capacity as the controlling rule means aggregate counted WLL requires the most tiedowns. Length means article-length rules control. A combined label means the floors are equal.
  • A blank lower-component WLL applies no extra reduction. It does not prove that every connector and anchor matches the strap rating.
  • Recalculate after changing units, path, blocking, hardware, load grouping, or cargo profile, then compare the result with the current rule text and an actual inspection.

Technical Details:

The calculation normalizes mass to pounds and length to feet, chooses the weakest entered WLL, applies the counted share for the securement path, and compares both capacity and regulatory count floors. Kilograms and metres are converted without changing the physical quantity.

Formula Core

Let Wa be assembly WLL and Wc a lower component or anchor WLL when one is entered. Effective WLL is the smaller value.

We=min(Wa,Wc)

If no lower component value is entered, We = Wa. Counted WLL per tiedown multiplies the effective WLL by path factor p and optional conservative service factor s.

Wcounted=Weps

For cargo weight G and optional planning reserve r, the represented legal aggregate floor is one-half the cargo weight and the planning target adds the reserve.

Wlegal=0.5G Wtarget=Wlegal(1+r) Ncapacity=⌈WtargetWcounted⌉

The final count is the maximum of one, capacity count, length count, and the applicable cargo-profile floor. Planned margin is planned tie-down count × counted WLL minus the planning target. Reserve and service factor are conservative, repo-authored planning adjustments; 49 CFR 393 does not prescribe those two optional percentages.

Rule Core

ConditionModeled minimum
Blocked against forward movementAt least 1 per 10 ft of article length or fraction
Not blocked, length ≤ 5 ft, weight ≤ 1,100 lb1
Not blocked, length ≤ 5 ft, weight > 1,100 lb2
Not blocked, length > 5 ft and ≤ 10 ft2
Not blocked, length > 10 ft2 plus 1 for every additional 10 ft or fraction
Wheeled or tracked heavy equipment, weight ≥ 10,000 lbFloor of 4
PathCounted share before service factor
Opposite-side over or around cargo100%
Vehicle anchor directly to cargo50%
Over or around cargo, returning to same side50%
Custom counted pathEntered 1% to 100%

Lookup Core

Manufacturer markings control when available. The built-in unmarked-material choices reproduce selected values from the federal WLL tables.

Material choiceWLL
1¾ in synthetic webbing1,750 lb
2 in synthetic webbing2,000 lb
3 in synthetic webbing3,000 lb
4 in synthetic webbing4,000 lb
⅜ in Grade 70 chain6,600 lb
½ in Grade 70 chain11,300 lb

Limitations and Safety Notes:

This is a general U.S. federal cargo-securement screen, not a loading instruction, inspection, or compliance determination.

  • Commodity-specific sections take precedence when they add requirements.
  • The heavy-equipment profile models a four-tiedown floor only; it does not model every placement, accessory, articulation, or parking-brake requirement.
  • Friction, pretension, tie-down angle forces, cargo strength, vehicle dynamics, edge protection, and anchor geometry are not engineering-calculated.
  • Use the actual marked WLL and the weakest component or anchor. Remove damaged, unreadable, incompatible, or unsuitable equipment from service.
  • Follow current federal, state, provincial, carrier, manufacturer, and site rules, and obtain qualified guidance when the load or method is uncertain.

Worked Examples:

General cargo with opposite-side straps

A 12,000 lb, 16 ft unblocked article has a 6,000 lb legal aggregate-WLL floor. Four opposite-side 2 in webbing tiedowns rated at 2,000 lb each count at full WLL when no lower component or service reduction is entered. Capacity requires 3 tiedowns, and the unblocked length rule also requires 3. Planning 4 provides 8,000 lb of counted WLL and a 2,000 lb modeled margin. The arithmetic passes, but the load still needs suitable anchors, restraint against rolling or shifting, and a physical inspection.

References: