What does daN mean on a ratchet strap?

Every ratchet strap made to EN 12195-2 carries a label with figures in daN. Here's what daN means, how it compares with breaking strength, and which number to look at when you're securing a load.

What daN means

daN stands for decanewton. One decanewton is 10 newtons, a unit of force.

As a rule of thumb, 1 daN is roughly the force of 1 kg. So a strap with a lashing capacity of 2,500 daN can hold roughly 2,500 kg of force in a straight pull. It's a measure of force, not weight, which is why the standard uses it.

Lashing capacity (LC)

The lashing capacity is the maximum force the strap is designed to take in use, in a straight pull. It's the headline figure on the label and the one to check first.

LC applies when the strap runs directly from the load to the vehicle, known as direct lashing.

Breaking strength

The breaking strength (often shown as BS or MBS) is the force at which the strap fails in testing. Under EN 12195-2 it must be at least twice the lashing capacity.

That's why a strap rated 2,500 daN LC is usually sold as a 5,000 kg strap. The 5,000 kg is the breaking strength. Never load a strap up to its breaking strength. Work to the lashing capacity.

Standard hand force (SHF) and standard tension force (STF)

The label also shows two figures about tensioning:

• SHF, standard hand force: the force the standard assumes you apply to the handle, normally 50 daN.
• STF, standard tension force: the tension the strap holds in the webbing after tightening with that hand force.

STF matters for top-over lashing, where the strap goes over the load and presses it down onto the deck. In that method it's the clamping force that holds the load, so STF is the figure that counts, not LC. A higher STF means more clamping force from each strap. Our ergonomic 50mm straps, with a reverse-action pull-down handle, are rated at 500 daN STF.

Reading the label

An EN 12195-2 label on a polyester strap is blue and shows:

• Lashing capacity (LC) in daN
• Standard hand force (SHF) and standard tension force (STF)
• Length and material
• The manufacturer and the standard, EN 12195-2

If the label is missing or unreadable, don't use the strap. There's no way to know its rating.

Which number should I use?

• Direct lashing, strap from the load to a lashing point: work to the LC.
• Top-over lashing, strap over the load: the STF decides how much clamping force each strap gives, and so how many straps you need.
• Breaking strength: a test figure. Don't plan a load around it.

The DVSA's load security guidance and EN 12195-1 explain how to work out how many straps a load needs.

Our straps

Our 5,000kg / 50mm ratchet straps are made to EN 12195-2 with a 2,500 daN lashing capacity. See how to use a ratchet strap for threading, tightening and releasing one properly.