Engine Hoist Boom Capacity Checker

How much an engine hoist can lift depends on the boom position you use and on your own hoist’s data plate, not just its headline rating. Enter the capacity for each position and the weight on the hook to see where you stand. For background, read Engine Hoist Capacity Chart by Boom Position: Why Extension Cuts Lift.

1. Choose the weight unit (lb or kg) for the engine and attached parts.
2. Enter the engine weight. Add the transmission or accessories that stay bolted on, plus anything else on the hook, such as a chain, sling or load leveler.
3. Choose the capacity unit exactly as printed on your hoist’s data plate: pounds, kilograms, US tons (2,000 lb) or metric tonnes (1,000 kg).
4. Enter one row per boom position, shortest reach first and longest reach last. Use the arrow buttons to reorder rows and add up to eight positions.
5. Select Check capacity. The results show utilization, margin and status for every position. They also name the longest position that stays within the rating you entered.

The tool has no default capacities or engine weights. Every number comes from you. Nothing you type is stored or sent anywhere. Switching units converts the numbers shown in the fields, but the calculation keeps using the exact values you typed, so a unit switch never changes a result.

Many engine hoists list a separate capacity for each boom extension, and the figures usually fall as the boom reaches further out. A single headline rating may therefore apply to only one position. The checker compares your load against every position you enter, using this arithmetic:

Each position gets one of three statuses: Within the rating you entered (under 100%), At the entered rating, zero margin (exactly 100%), or Exceeds the rating you entered (over 100%). There are no extra “caution” bands. If a longer position shows a higher capacity than a shorter one, the tool asks you to re-read your data plate, because the entry may be mistyped or in the wrong order.

• Hoist capacity per position: read the label or data plate on the boom, or the maker’s manual. Copy the unit as printed.
• Engine weight: weigh it, or use a figure from a source you trust for your exact engine and its configuration.
• Attached parts: include the transmission, accessories, chain, sling, load leveler and anything else that hangs from the hook.

A 1998 NHTSA/NCSA research note analyzed CPSC NEISS emergency-room data from November 1994 to October 1995. This is old data. It states: “Approximately three-fourths (74%) of the persons injured in motor vehicle jack failures were injured as a result of being struck by the vehicle as it fell from the jack.”

NIOSH FACE report 99CA006 (1999) describes a 37,500 lb transit bus on shop-made stands, not a car or motorcycle: “A 48-year old male mechanic (decedent) died when he was crushed by a bus that fell off jack stands.” Its recommendation is to “ensure employees use only tools and equipment that have been tested, certified and rated.”

The cited sources do not provide an official US fatality count for jack stands or jacks, and this page does not state one. ASME PASE, the Safety Standard for Portable Automotive Service Equipment, covers shop cranes and engine stands in its scope. Never work under a vehicle supported only by a jack.

All weights are converted internally to kilograms using the international pound definition, 1 lb = 0.45359237 kg exactly. A US ton is 2,000 lb and a metric tonne is 1,000 kg. Each value you type is kept at full precision; switching units only changes what the field displays. Utilization is compared unrounded and displayed rounded up to one decimal, so 100.04% shows as 100.1% and counts as exceeding. Blank, zero or negative capacities are excluded. A 99,999 cap on each field exists only to sanitize input; it is not a safety limit. The output is arithmetic on typed numbers, not an assessment of the hoist, engine weight or rigging.

• NHTSA/NCSA Research Note (1998): Injuries Associated With Hazards Involving Motor Vehicle “Jack Failures”: jack-failure injury quote (CPSC NEISS 1994-95)
• NIOSH FACE Report 99CA006: bus on jack stands case and recommendation
• ASME PASE: Safety Standard for Portable Automotive Service Equipment: reference authority (cited by name and scope only)
• Wikipedia: Pound (mass): 1 lb = 0.45359237 kg
• Wikipedia: Short ton: 1 US ton = 2,000 lb
• Wikipedia: Tonne: 1 tonne = 1,000 kg
• Your hoist’s data plate and the maker’s manual: the authority for every limit

Last updated: October 2026

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