How do you calculate LC for cargo securing?
To calculate LC for cargo securing, the most common method — tie-down lashing — actually sizes the number of straps rather than the LC itself, using the EN 12195-1:2010 formula: n ≥ (c − μ) × m × fS / (2 × μ × STF × sin α). Plug in the cargo mass m (kg), the friction factor μ, the strap tension STF (daN) and the angle α. For a typical 4,000 kg load on a wooden deck (μ = 0.3), a strap with STF = 400 daN and a 90° angle, you get about 11 straps to the front. Add anti-slip mats (μ = 0.6) and just 3 straps are enough. Below are all the numbers, tables and a worked example — in 2 minutes, without Excel.
The classic roadside mix-up: a driver reads the label, sees a big LC 2500 and assumes that number is what “holds” the load. For tie-down lashing, it isn’t. This guide shows how to calculate LC for cargo securing step by step — which figure actually does the work, and how to size your securing in your head in a couple of minutes.
What are LC and STF — and why do drivers mix them up?
A strap label carries two key forces, and they do different jobs. First, LC (Lashing Capacity) is the rated working strength of the strap; therefore it matters for direct lashing (diagonal, loop), where the strap restrains the load directly. STF (Standard Tension Force), on the other hand, is the residual tension left after you tighten the ratchet; as a result, it presses the load onto the deck and creates friction in tie-down lashing. In short: pull the load directly and LC does the work; press it down from above and STF does the work instead.
| Symbol | What it is | Where to find it / typical value |
|---|---|---|
| LC | Rated working strength of the strap (Lashing Capacity), daN | On the label. Textile straps: usually 1,000–5,000 daN |
| STF | Residual tension after hand-tightening, daN | On the label. Ratchet straps: ~300–500 daN |
| SHF | Standard Hand Force applied to the handle | Always 50 daN per EN 12195-2 |
| BF | Breaking Force | ≈ 2 × LC (built-in safety margin) |
| μ | Friction factor between load and deck | Wood–steel ≈ 0.3; with an anti-slip mat ≈ 0.6 |
| α | Vertical angle of the strap to the deck | Ideally ~90°; the closer to 90°, the more effective the down-force |
| c | Acceleration coefficient (inertia during manoeuvres) | 0.8 forward; 0.5 rearward and sideways |
Here is a handy shortcut for mental maths: 1 daN ≈ 1 kg. So in practice you can add and divide the cargo mass in kilograms and the label forces in daN directly, because the units line up.
Acceleration coefficients under EN 12195-1:2010 (road transport)
The standard defines how hard the load tries to break free during a sharp manoeuvre; in other words, that is the coefficient c (a fraction of the weight). Clearly, the most severe case on the road is emergency braking, when the load moves forward.
| Direction | Sliding (c) | Safety factor fS |
|---|---|---|
| Forward (braking) | 0.8 | 1.25 |
| Rearward | 0.5 | 1.1 |
| Sideways (cornering) | 0.5 (0.6 for unstable loads) | 1.1 |
| Vertically down (cz) | 1.0 | - |
The formula to calculate LC for cargo securing in 2 minutes
For tie-down (frictional) lashing under EN 12195-1:2010, the number of straps n needed to keep the load from sliding is:
Where c is the directional coefficient (0.8 forward), μ is friction, m is the cargo mass in kg, fS is the safety factor (1.25 forward), STF is the strap tension in daN and α is the strap angle. The 2 in the denominator is there because a tie-down strap runs over the load and tensions both legs. Always calculate for “forward” — that is the governing direction.
Calculating LC for cargo securing: a 4,000 kg load on a wooden deck
Given: m = 4,000 kg, μ = 0.3 (wood on wood), strap STF = 400 daN, α = 90° (sin α = 1), forward direction (c = 0.8; fS = 1.25).
Eleven straps for a single load is expensive, slow and almost impossible to fit. The takeaway is clear: at low friction, tie-down lashing is inefficient. The fix isn’t more straps — it’s raising friction with anti-slip mats.
Why do anti-slip mats cut the number of straps by three?
Same load, but now with anti-slip mats underneath — μ = 0.6:
One item — a mat costing a couple of euros — turns 11 straps into 3. Here is how friction drives the securing for that same 4,000 kg load (strap STF = 400 daN, 90° angle, forward direction):
| Friction factor μ | Example surface | Straps needed (forward) |
|---|---|---|
| 0.2 | Smooth plastic on steel | 19 |
| 0.3 | Wood on steel / wood on wood | 11 |
| 0.4 | Rough timber, clean dry deck | 7 |
| 0.5 | Rubber, anti-slip coating | 4 |
| 0.6 | Anti-slip mat under the load | 3 |
In short, to calculate LC for cargo securing in 2 minutes you follow three steps: first raise μ (mats), then size the straps with the formula, and only for heavy, compact loads switch to direct (diagonal) lashing, where LC does the work directly. Check both directions — forward and sideways — and take the larger number.
FAQ: how to calculate LC for cargo securing
What is LC on a cargo securing strap?
LC (Lashing Capacity) is the strap’s rated working strength in decanewtons (daN), printed on the label. It shows the force the strap can safely hold in direct lashing. The Breaking Force (BF) is roughly twice the LC — that is the built-in safety margin. For mental maths: 1 daN ≈ 1 kg.
What is the difference between LC and STF?
LC is the strap’s rated working strength and matters in direct (diagonal) lashing, where the strap restrains the load. STF is the residual tension after ratchet tightening and matters in tie-down lashing: it creates friction against the deck. Pull directly — calculate with LC; press down — calculate with STF.
How many straps do you need to secure a load?
For tie-down lashing, the number of straps is n ≥ (c − μ) × m × fS / (2 × μ × STF × sin α). For a 4,000 kg load on a wooden deck (μ = 0.3, STF = 400 daN, 90° angle) that gives about 11 straps to the front. Always calculate for the governing direction — forward.
How do anti-slip mats affect the number of straps?
Mats raise the friction factor μ from about 0.3 to 0.6, and the number of straps in the formula drops sharply. For a 4,000 kg load that is the difference between 11 straps without mats and 3 straps with them. A cheap mat saves straps, tightening time and lashing points.
What strap angle is considered correct?
For tie-down lashing, the vertical strap angle α should be as close to 90° to the deck as possible — that gives maximum down-force (sin α = 1). At 30° the effect halves. For direct lashing the opposite is true: a flatter angle better restrains the load against horizontal movement.
What is STF and where is it shown?
STF (Standard Tension Force) is the residual tension left in the strap after tightening by hand with 50 daN of force (SHF). It is printed on the strap label in daN; ratchet straps usually show 300–500 daN. The higher the STF, the stronger the down-force and the fewer straps you need in tie-down lashing.
Author: LPX Trade Expert Editorial Team — a supplier of EN 12195 cargo securing equipment. Prepared from the applicable standards and from EU roadside-inspection practice.
Last updated: 7 July 2026.
Sources: EN 12195-1:2010 (+AC:2014) “Calculation of securing forces”; EN 12195-2 (textile lashing straps; LC/STF/SHF/BF marking); ES direktyva 2014/47/ES (roadside technical inspection).
LPX Trade straps, chains and rigging are certified to EN 12195-2 with testing. Match the securing gear to your calculation in our catalogue at lpxtrade.lv.