Bottle Jack Reach & Capacity Selector

The bottle jack you need has a rated capacity at least equal to the load at your lift point, a closed height that fits under that point, and enough stroke and extension to reach your target height. Enter your jack’s label numbers below to check all three. Never work under a vehicle supported only by a jack; this tool is not a substitute for jack stands.

1. Find the load at the lift point in your vehicle owner’s manual and enter it in lb or kg. The tool does not estimate vehicle weights, axle shares or lift-point loads.
2. Read the rated capacity on the jack label or in its manual. Choose whether the label means short tons (US tons) or metric tonnes. If the manual gives a pound or kilogram figure, use it to decide.
3. Measure the lift-point height now, from the ground to the lift point, and decide how high that point must go (the target height).
4. Enter the jack’s closed (minimum) height, ram stroke, extension screw length and any add-on extender height from the label or manual. Enter 0 for parts you don’t have. If the maker gives only a maximum height, switch to “I only know the maker’s max height”.
5. Select Check my jack. You get a pass or fail line for capacity, fit and reach, plus the clearance and the reach margin.

The result compares only the numbers you enter. It applies no multiplier, margin or derating, and the jack maker’s rating and manual always govern. Unit switches convert the values already typed, so you can swap between inches and millimeters, or pounds and kilograms, without losing your entries. The boxes show rounded conversions, but the check keeps using the exact value you originally typed until you edit it.

Everything is converted to pounds and inches first, then three checks run:

• Capacity check: rated capacity in lb = rating × 2,000 (short tons) or rating × 1,000 kg ÷ 0.45359237 (metric tonnes, about 2,204.62 lb each). It passes if the load is no more than the rated lb. The tool also shows the load as a percent of the rating and the minimum rating that matches the entered load, in short tons and in metric tonnes, rounded up to 0.01 so the figure shown is never below your load. A load exactly equal to the rating shows “at the rating, not above it”.
• Fit check: clearance = lift-point height now − closed height. It passes if clearance is zero or more. If it fails, the reach check still shows.
• Reach check: maximum height = closed height + stroke + extension screw + add-on. Reach margin = maximum height − target height. It passes if the margin is zero or more. If the target is not above the current lift-point height, no reach result is given.

The table below uses hypothetical numbers for arithmetic, not a real jack.

The same rating means different pounds depending on the ton: 2 short tons is 4,000 lb, while 2 metric tonnes is 2,000 kg, about 4,409.2 lb.

Which “ton” is on your jack?

Bottle jack listings are inconsistent. Some print “N tons” in the spec block while the title gives a pound figure that only matches metric tonnes (about N × 2,204.6 lb); others mean US short tons (N × 2,000 lb). The tool never assumes which one is meant. Check the manual or label for the lb or kg figure and choose the matching unit.

Do you need an extension screw or a longer stroke?

The tool also works out closed height + stroke on its own. If that falls short of the target but the full height with the extension screw and add-on reaches it, the result says the jack needs the extension screw and/or add-on to reach the target. If even the full height falls short, you need a jack with more stroke, a taller closed height that still fits under the lift point, or a different extension. Extension screws and add-on extenders carry their own maker ratings and instructions, so follow those as well as the jack’s.

Where to find each number

Rated capacity, closed height, stroke and extension screw length come from the jack label or manual. Lift-point locations and the load at each point come from the vehicle owner’s manual. We don’t list typical values because they vary by model. In our internal T1 silo shelf dataset (Amazon query “bottle jack”, snapshot 2026-09-27), only 1 of 16 non-sponsored, priced bottle jack listings (rated 2 to 20 tons) stated a lift range in its title, so the label and manual are the place to look.

Lifting a house or structure?

This tool is for vehicle lift points only. It does not size jacks for lifting a house, deck, shed or any other structure. For buildings, talk to a qualified professional.

All calculations run in your browser from the values you enter; nothing is stored or sent. Exact unit definitions: 1 in = 25.4 mm, 1 lb = 0.45359237 kg, 1 short ton = 2,000 lb, 1 metric tonne = 1,000 kg. Derived from those, 1 metric tonne = 1,000 ÷ 0.45359237 lb, which is about 2,204.62 lb; the tool uses the full derived value, so 1,000 kg against a 1-tonne rating is exactly at the rating. Inputs must be numbers greater than 0 (extension screw and add-on may be 0), and values over 1,000,000 are rejected as typos. Display is rounded to 0.1 in, 1 mm and 1 lb, and the minimum rating is rounded up to 0.01 ton; the math is unrounded. No safety multiplier is applied anywhere.

Standards and incident data: portable automotive lifting equipment, including automotive hand jacks and stands, falls under ASME PASE, the Safety Standard for Portable Automotive Service Equipment (current edition PASE-2024; cited by name and scope only). An NHTSA/NCSA research note from September 1998, based on CPSC NEISS data from November 1994 to October 1995 (old data), 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: “A 48-year old male mechanic (decedent) died when he was crushed by a bus that fell off jack stands.” Its recommendation reads: “ensure employees use only tools and equipment that have been tested, certified and rated.” No official US fatality count for jacks or jack stands exists in these sources. On 2026-10-12, CPSC Recalls API product-name queries for floor jack, bottle jack, jack stand, scissor jack, transmission jack, motorcycle lift and car ramp returned zero records; that does not establish that no recalls exist, so check the recall pages for your own equipment.

• Wikipedia: Inch (1 in = 25.4 mm, exact)
• Wikipedia: Pound (mass) (1 lb = 0.45359237 kg, exact)
• Wikipedia: Short ton (2,000 lb, exact)
• Wikipedia: Tonne (1,000 kg, exact; about 2,204.62 lb, derived)
• ASME PASE – Safety Standard for Portable Automotive Service Equipment
• NHTSA/NCSA Research Note (1998): Injuries Associated With Hazards Involving Motor Vehicle “Jack Failures”
• NIOSH FACE Report 99CA006
• Internal T1 silo shelf dataset (garagehow research, Amazon query “bottle jack”, snapshot 2026-09-27): listing counts only

Last updated: October 2026. Never work under a vehicle supported only by a jack. Follow the jack maker’s rating and manual and ASME PASE.

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