Rated capacity vs working load limit: meaning and why it matters
Rated capacity is the most a crane may lift in a given configuration at a given radius, read from its load chart. A working load limit, or WLL, is the most a sling, shackle or other piece of gear is rated to carry in a stated use, read from its tag.
Two sources, two questions
The crane's rated capacity answers "can this crane, set up this way, at this radius, hold this load?" It comes from the load chart, adjusted by the deductions. See crane capacity deductions.
A working load limit answers "can this piece of gear carry this force?" It is marked on the sling's tag, stamped on the shackle's body or listed for the hook, and it depends on how the gear is used. A sling's limit changes with the hitch and the leg angle. Terms differ by standard and manufacturer, so read the tag's own wording.
Try one question
Question 1 of the free 10-question check on NCCCO written. No signup.
Operations
Which action creates side loading on a crane boom?
Choose an answer to begin
A lift passes only if every part does
Take our invented numbers. A crane's net capacity at the lift radius is 9,000 lb, and the load weighs 8,000 lb. The crane is fine. The load hangs on a two-leg sling with equal legs at 45 degrees from horizontal, and each leg's rating is 5,000 lb at that use. Each leg's share is 4,000 lb, and the angle factor of 1.414 raises its tension to about 5,660 lb. The leg is overloaded even though the crane is not. The shackles, the lifting lugs on the load and the hook each have to pass the same test.
The working load limit already includes the manufacturer's design margin, so do not add another margin and do not treat it as a floor you may exceed a little.
Ask Hook before you buy AI your Boom Angle study buddy
See what's on the NCCCO written exam, take the free 10-question check, or find the plan that fits you.
The NCCCO written course
Available now · instant accessLearn every outline domain, work load charts step by step, then prove it on timed exams.
- 8modules of lessonsEvery task on the outline
- 3timed practice exams95 questions in 90 minutes and 28 in 60
- 437practice questionsEach one explained
- 2worked calculationsStep by step
- 1week-by-week study planSet to your exam date
Turn a practice answer into a study step. In untimed practice, ask Hook AI about any question you answer, follow up, then see your weakest topics and what to drill next.
Instant access. Terms and refunds · Secure checkout by Stripe
Every answer comes with a full explanation.
Common mix-ups
- Using the crane's capacity as the answer for the whole lift. It clears only the crane.
- Using the sling's vertical rating on a bridle. The angle changes the leg's tension.
- Using a tag from a different sling or a worn one. A missing or unreadable tag means the rating is unknown.
- Mixing up capacity of the crane with the weight of the load. Capacity is a limit. Weight is a load.
On the NCCCO written exam
Core expects you to read the crane's rating and to know that rigging has its own limits, as part of task 3.5 (rigging devices) in Technical Knowledge, about 23% of Core under the 01/25 handbook. Questions may give both a crane capacity and a sling rating and ask which one limits the lift.
Practice it
The sling capacity calculator checks choker, basket and bridle setups against a rating. Read choker vs basket hitch, then crane capacity deductions for the crane side. The crane terms glossary lists the set.
Know the terms? Take the free 10-question check
Take the free 10-question check. It is scored by the Core outline domains and needs no signup, so you see whether site, operations, technical knowledge or load charts costs you the most points. Boom Angle's course then gives you a question bank with each answer key checked by a second solve, timed practice exams, and a study plan built from your exam date.
Sources
Show the list
- 29 CFR 1926.251: Rigging equipment for material handling, OSHA.
- Guidance on Safe Sling Use: Alloy Steel Chain Slings, OSHA.
- Hoisting and Rigging Fundamentals, TR244C Rev. 5, U.S. Department of Energy, sling loading.
- Mobile Crane Operator Candidate Handbook, CCO, Core outline tasks and weights (01/25 revision). Task numbers on this page follow it.
Facts checked 25 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.
Your next step
Ready to see where you stand on NCCCO written?
Free, untimed and scored by domain. No signup.
Start the free 10-question checkCore + Specialty course. Lessons, timed practice exams and a plan around your exam date. Get Core + Specialty course · $99 See the plans or read the free sample lesson.Terms and refunds