Rated in Kilonewtons, Calculated in Newtons
Almost everything in a lifting or fall-protection kit carries a kilonewton number: it is etched on the karabiner spine, printed on the anchor plate, moulded into the sling label. The moment you start working out what a real load does to that kit — a sling leg at an angle, a shared anchor, a factored dynamic pull — the arithmetic runs in newtons, because that is the unit the formulas are written in. The step between the two is a decimal shift, and the whole job is keeping the zeros straight when a slip reads as a factor of a thousand.
What the Stamped Number Really Says
It is a strength, not a permission
Direction changes the rating
Hardware talks force, crews talk tonnes
Static weight is the smallest number of the day
Taking a Rating Apart on Site
Three or four keystrokes cover the checks that come up while the kit is still on the ground.
Type the rating off the product
Enter 22, 12 or 6 in the left field and the newton value appears as you type — no button to press. A comma works in place of the decimal point, so 7,5 and 7.5 both give 7 500 N.
Switch the right side to kilogram-force for the crew
Search the right-hand dropdown for kilogram-force or tonne-force when the figure has to go into the lift plan in the language the crew uses. Every force unit in the app sits in both lists, so the page doubles as a kN → tf check.
Reverse it when the calculation gives newtons
A leg-tension or dynamic-factor result lands in newtons, while the label you are comparing it against is in kilonewtons. Press the swap button (↔) and feed the newton figure back the other way.
Copy the bare figure into the lift plan
The copy button on either field puts the plain number on the clipboard, with no unit and no thousands spacing, ready to drop into a calculation sheet or a permit form. Ctrl + C inside a field does the same.
Ratings You Meet on a Lifting or Fall-Protection Kit
The same rating written three ways: as it appears on the kit, as the calculation sees it, and as the mass that would hang from it at standard gravity.
| Rated item | Marked rating | Newtons | Equivalent hanging mass | What the figure is |
|---|---|---|---|---|
| Maximum arrest force on the body | 6 kN | 6 000 N | 612 kgf (0.61 t) | Ceiling the harness and energy absorber must keep the wearer under |
| Karabiner, gate open | 7 kN | 7 000 N | 714 kgf | The weakest of the three marks on the same connector |
| Structural anchor point | 12 kN | 12 000 N | 1 224 kgf (1.22 t) | Typical European single-user anchor test level |
| Anchorage, 5 000 lbf rule | 22.24 kN | 22 241 N | 2 268 kgf (2.27 t) | The US per-worker anchorage figure, written in imperial |
| Steel karabiner, major axis | 22 kN | 22 000 N | 2 243 kgf (2.24 t) | Minimum breaking strength along the spine |
| Screwgate connector, major axis | 25 kN | 25 000 N | 2 549 kgf (2.55 t) | Common rating on heavier steel gear |
| Chain hoist, 2 t | 19.61 kN | 19 613 N | 2 000 kgf (2 t) | A mass rating converted into the force it produces |
| Round sling, 3.2 t working load limit | 31.38 kN | 31 381 N | 3 200 kgf (3.2 t) | A permitted load, already divided down from breaking strength |
Read down the last column and the pattern is clear: some of these numbers are strengths, some are allowances, and two of them are masses in disguise. Converting kilonewtons to newtons never changes which kind you are holding — it only makes the arithmetic easier.
Why This Page Suits Rigging Work
Ratings resolve as you type
Both fields are live, so working through a kit — 22, then 7, then 12 — takes one keystroke each, with nothing to submit in between.
Tonne-force and kilogram-force in the same list
Both searchable dropdowns carry every force unit in the app, so a kilonewton rating can be read straight out as tonne-force for a lift plan.
Two-way against a calculation
The swap button turns the page into an N → kN check, the direction you need once a leg-tension result has to be compared with a stamped rating.
Numbers a permit form accepts
Copy hands over the clean value with nothing to strip out, which is what a lift plan, a rescue calculation or an inspection record expects.
Questions Riggers Ask About kN Markings
A hoist says 2 t and the karabiner says 22 kN — which one is stronger?
They are not describing the same quantity, which is why they cannot be compared until one is converted. Tonnes and kilograms are mass; kilonewtons and newtons are force. A hanging mass of 2 000 kg pulls with 2 000 × 9.80665 = 19 613 N, or 19.61 kN — so a 2 t hoist rating and a 22 kN connector rating land in the same neighbourhood, but the hoist number is a permitted working load while the connector number is a breaking strength. Once both sit in newtons the comparison is honest; while one is in tonnes it is guesswork.
Can I hang 22 kN worth of load on a 22 kN connector?
No. That mark is a minimum breaking strength — the point at which a sample tore in a test machine. Working practice divides it by a design factor, commonly five for lifting accessories and higher again for man-riding or rescue work, which turns 22 000 N of strength into something in the region of 4 400 N of permitted load. Slings and shackles, by contrast, are usually marked with the working load limit itself, so on those the printed figure is the allowance and the breaking strength is several times higher.
Why does spreading a lift over two legs not halve the tension?
Because only the vertical component of each leg carries the load, and the wider the legs are spread the smaller that component becomes. Each leg of a two-leg sling takes half the load divided by the cosine of its angle from vertical. A 1 000 kg load is 9 807 N hanging straight down; at a 60° included angle each leg sees about 5 662 N, at 90° about 6 934 N, and at a 120° included angle each leg carries the full 9 807 N — as much as if it were holding the whole load alone. Beyond that the numbers climb steeply, which is why included angles wider than 120° are avoided.
Where does the 6 kN limit in fall protection come from?
It is a limit on the human body, not on the hardware. Work on survivable deceleration settled on roughly 6 000 N as the peak a harnessed adult can take through a full-body harness without serious internal injury, and the standards were written around that. The energy absorber in a lanyard exists precisely to hold the peak under it: the pack tears in a controlled way, stretching the arrest over a longer distance so the force never reaches what a rigid connection would produce. The anchor above is then rated far higher — 12 000 N and up — because it has to survive the same event with margin, while the person must not exceed the limit at all.
How much does a shock load add to the newton figure?
Enough to change the answer completely. A load lifted smoothly produces close to its static value; snatch it off the ground, stop it abruptly, or let it swing and the peak can be two, three or more times higher, depending on how quickly the motion is arrested and how much stretch the system has to soak it up. Crane and hoist design codes handle this with dynamic factors applied to the static force, and rope work uses fall factors for the same reason. The practical consequence: a 10 000 N static result may have to be checked against 20 000 N or 30 000 N of real peak — so convert first, then multiply, never the other way round.
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