How Much Weight Can a Caster Hold? Capacity Math (2026)

Quick answer: typical caster weight ranges #

A typical industrial caster holds 75 to 1,200 pounds per wheel, with light-duty units starting near 75 lb and extra-heavy-duty kingpinless rigs reaching 6,000+ lb. The number you read on the spec sheet is the rated capacity for one caster on a smooth floor at slow walking speed, and it is only valid if you size the cart for 3 of 4 casters carrying load (because one floats on any real floor) and apply a minimum 1.33x safety factor for dynamic motion. Skip those two corrections and the catalog number lies to you.

• Light duty (2 to 3 inch wheels): 75 to 350 lb per caster. Office, retail, light institutional.
• Medium duty (4 to 5 inch wheels): 250 to 900 lb per caster. Utility carts, food service, racks.
• Heavy duty (6 to 8 inch wheels): 500 to 2,500 lb per caster. Material handling, manufacturing, dock carts.
• Extra heavy duty (10 to 12 inch wheels, kingpinless): 2,000 to 6,000+ lb per caster. Tow trains, AGV platforms, aerospace tooling.

Caster capacity by wheel diameter (full table 2" to 12") #

Wheel diameter is the most visible capacity driver, but it does not set capacity by itself. A 5-inch wheel rated at 350 lb on a stamped-steel rig and a 5-inch wheel rated at 1,400 lb on a forged kingpinless rig are both real products. The table below shows the typical band you should expect at each wheel size across all four brands we stock. Treat the lower number as economy stock and the upper number as full industrial. If a vendor quote sits well below the lower number for a stocked size, that is your signal to ask why.

Bigger wheels do more than carry weight. They roll over expansion joints, doorway thresholds, and floor cracks without shock-loading the rig. A 4-inch wheel hitting a 1/2-inch crack at speed slams the wheel hub like a hammer; an 8-inch wheel rolls across the same gap. If your floor has joints or your route crosses dock plates, push the wheel size up before you push the rated capacity up. Cross-check sizing with the worked examples in our Caster Load Capacity Calculator & Weight Rating Guide.

How wheel material changes capacity (poly vs rubber vs phenolic vs cast iron) #

Wheel material can swing rated capacity by 4x at the same diameter. A 6-inch soft-rubber wheel might be rated 410 lb. A 6-inch forged-steel wheel can be rated 2,500 lb. Same size, same plate, very different number. The harder the wheel, the higher the capacity, and the worse the noise, ride, and floor protection. Pick the material to fit the floor and the load, not just the load.

• Soft rubber (60 to 75A durometer): Lowest capacity, best floor protection, quietest ride. Typical 100 to 600 lb at 6 inches. Office, healthcare, light cart.
• Hard rubber (90A): Mid capacity, decent floor protection. Typical 300 to 900 lb at 6 inches. Utility cart, light material handling.
• Polyurethane on steel hub (95A): The industrial standard. Quiet, non-marking, high capacity. Typical 600 to 1,800 lb at 6 inches. Warehouse, manufacturing, racking.
• Phenolic (resin): High capacity, high temp, hard ride. Typical 1,200 to 2,500 lb at 6 inches. Bakery, foundry, paint line.
• Cast iron / forged steel: Highest capacity, terrible floor protection, loud. Typical 1,500 to 3,500+ lb at 6 inches. Foundry, mill, scrap-handling.
• Pneumatic (air-filled rubber): Lowest capacity per wheel, best shock absorption. Typical 250 to 700 lb at 8 to 10 inches. Outdoor, gravel, uneven terrain.

Bearing type effect on dynamic capacity (roller vs precision vs delrin) #

The wheel bearing controls how much of the rated capacity you can use in motion (dynamic load) vs at rest (static load). A wheel rated 1,200 lb static with a plain bore might only carry 600 lb dynamic at 3 mph. The same wheel size with sealed precision ball bearings can run the full 1,200 lb dynamic. Bearings are also the lifespan variable: a plain bore on a wet floor seizes in months; a sealed precision bearing runs years.

• Plain bore: No bearing. Cheapest, lowest dynamic rating, shortest life. Use on light, slow, indoor applications only.
• Roller bearing: Cylindrical rollers in a cage. The industrial workhorse. Good dynamic capacity, fair lifespan, easy to lubricate.
• Precision ball bearing (single or double row): Best dynamic capacity, longest life, lowest rolling resistance. Required for tow and AGV.
• Sealed precision (sealed for life): Same performance as precision ball, no maintenance, washdown-friendly. Spec for food service and medical.
• Delrin (acetal): Polymer bearing, low friction, light load. Quiet and corrosion-proof. Use for light-duty, washdown, or chemical exposure.
• Tapered roller: Side-load capable. Spec for heavy-duty kingpinless rigs that take cornering loads in tow.

Bearing choice also drives the swivel rating, not just the wheel rating. A heavy-duty wheel on a light-duty plain-bore swivel raceway will fail at the swivel before the wheel. Always confirm both the wheel bearing and the swivel raceway match the duty class. Detailed bearing comparisons live in the spec section of our Dynamic Load Rating reference.

Rig construction limits (kingpin vs kingpinless) #

The same wheel on two different rigs can have wildly different capacity, and the rig is the part that fails first under shock load. A kingpin caster uses a single bolt or rivet through the swivel raceway to hold the rig together; a kingpinless caster welds or forges the swivel as a single piece. Kingpin rigs are cheaper and lighter; kingpinless rigs are heavier, last longer under shock, and dominate the heavy and extra-heavy duty market.

• Stamped steel kingpin: Light to medium duty. 75 to 600 lb per caster. The most common cart caster. Good for indoor use under rated load.
• Drop-forged kingpin: Medium to heavy duty. 600 to 1,500 lb per caster. Stronger than stamped steel, more compact than kingpinless.
• Welded kingpinless: Heavy duty. 1,000 to 3,500 lb per caster. Standard for material handling, warehouse, and heavy industrial.
• Forged kingpinless: Extra heavy duty. 2,000 to 6,000+ lb per caster. The Albion 16/18 and Hamilton XHD families. Tow trains, AGV, defense tooling.
• Maintenance-free sealed kingpinless: Extra heavy with sealed swivel raceway. Longest life under continuous duty. Spec for 24/7 operations.

Kingpin failure is the most common single-point failure on heavy carts. The kingpin shears under shock, the rig opens up, and the wheel walks off the cart. If your cart will ever be towed, jolted, dropped on a dock plate, or run continuously at industrial speed, spec kingpinless and skip the kingpin entirely. Brand families that lead in kingpinless: Albion, Hamilton, and Durastar in the duty bands we stock.

Safety factor math: ICWM 1.33, aerospace 2.0, defense 1.5 #

The Industrial Caster & Wheel Manufacturers (ICWM) standard requires a minimum 1.33x safety factor for dynamic load on industrial casters, and aerospace, defense, and medical applications run higher. The factor is applied on top of the per-caster effective load (after the divide-by-3 correction), and it accounts for floor irregularity, cornering, shock, operator misuse, and the fact that real cart weights creep up over time as operators add tooling and dunnage.

The safety factor is not optional. It is the math that turns a static rating from a manufacturer test into a real-world capacity that survives a shift, a year, and a decade. We see new procurement buyers strip the safety factor to hit a budget number; the rig fails inside the warranty window and the customer pays twice. See the deeper math in our Caster Safety Factor article and the shock-load explanation in Shock Load Rating.

3 vs 4 vs 6 caster math (one always floats) #

On any 4-caster cart on a real floor, only 3 of the 4 wheels carry meaningful load at any moment. The fourth caster floats because no shop floor is perfectly flat, and the cart frame flexes enough to lift one corner off the ground. That is why every load-rating math you see in our articles divides cart weight by 3, not 4. Skip this correction and the rated capacity you ordered is 33% under what you actually need.

Three-caster tripod carts (one swivel front, two rigid back, or vice versa) are statically determinate and all three wheels always carry load. That is why some hospital beds and lab carts use a tripod layout. The trade-off is reduced lateral stability under offset load, which is why most industrial carts use four casters and accept the divide-by-3 correction.

Floor condition derating (concrete, epoxy, grating, expansion joints) #

Rated capacity assumes a smooth floor at slow walking speed. Real floors derate the rated capacity, sometimes by 30 to 50%. Expansion joints, dock plates, grating, cracks, drains, and floor patches all hammer the wheel as it crosses, which means the dynamic load spike on impact is 2 to 4x the static load. The rated capacity has to absorb that spike or the wheel splits, the bearing seizes, or the rig welds crack.

• Smooth sealed concrete: 100% of rated capacity. The reference floor for all manufacturer load tests.
• Epoxy or urethane coated concrete: 100% of rated capacity (use polyurethane wheels only to protect coating).
• Polished or stamped concrete with patches: 80 to 90% of rated capacity. Spec one wheel size larger if route crosses patches.
• Concrete with expansion joints (1/4" or wider): 70 to 80% of rated. Bigger wheel rolls across; smaller wheel slams.
• Steel grating (forge, foundry, dock): 60 to 70% of rated. Spec phenolic or forged steel wheel and oversize.
• Asphalt outdoor: 70 to 80% of rated, plus shock absorption (pneumatic). Heat softens; aggregate gouges.
• Tile or terrazzo: 90% of rated, but soft rubber or polyurethane required to prevent surface damage.
• Wood floor (older facility): 50 to 70% of rated. Plank flex amplifies dynamic load.

The derating is not a manufacturer warranty position; it is a real-world engineering correction. Manufacturer load tests run on a smooth lab floor at slow rotation. Your floor is not their floor. The most reliable spec process is to pick the wheel and rig for the worst-case floor your cart will see, not the average. We walk through floor matching by application in the floor-and-environment section of our Industrial Casters Complete Guide.

Dynamic vs static load rating #

Static load rating is the weight a caster holds at rest; dynamic load rating is the weight a caster carries in motion. Dynamic is always lower, sometimes much lower, because a moving wheel takes shock from floor irregularity, cornering forces, and acceleration loads that a stationary wheel does not. Catalog numbers are usually dynamic ratings on industrial casters, but always confirm the spec sheet column header before you size. Confusing the two will under-spec a cart by 30 to 100%.

If your cart sits in a rack 95% of the time and only rolls during reload, you can spec to static. If your cart moves under load every shift, spec to dynamic. If your cart is towed, spec to tow rating (which most catalogs do not list directly, so size 50 to 75% above dynamic). Detailed definitions live in our Static Load Rating and Dynamic Load Rating articles.

Step-by-step: calculate per-caster load for your cart #

The defensible per-caster load math is 5 steps: gross loaded weight, divide by 3, apply 1.33x safety factor, derate for floor, then size up to the next stocked rating. We use this same math on every load-rating RFQ at our Mansfield, TX warehouse, and the answer matches the math on the load calculator at caster load calculator. Here is the step-by-step.

1. Step 1 - Gross loaded weight: Total weight of the loaded cart, including the cart frame, payload, dunnage, tooling, and operator if they ride. Example: 4,800 lb.
2. Step 2 - Divide by 3 (not 4): 4,800 / 3 = 1,600 lb per caster effective load.
3. Step 3 - Apply 1.33x safety factor: 1,600 x 1.33 = 2,128 lb per caster minimum required rating.
4. Step 4 - Floor derating: If route crosses expansion joints (70 to 80% of rated), required rating becomes 2,128 / 0.75 = 2,837 lb per caster.
5. Step 5 - Round up to next stocked rating: Closest standard heavy-duty stock is 3,000 lb per caster. Order to that.

If your cart has 6 casters or more, divide by (n minus 1 or n minus 2) instead of (n minus 1) for safety, since two corners can float on a long platform. The math is the same; only the divisor changes. The stocked-rating round-up is critical: you do not want to be at 2,128 lb required and 2,200 lb rated. Round up to the next standard size and bank the headroom.

When to spec up: continuous duty, towing, AGV, shock loads #

Five operating conditions push you to spec a higher capacity than the basic divide-by-3 plus 1.33x safety factor math suggests. If any one of them describes your cart, bump the per-caster rating one stocked size larger than the math would call for. The cost difference is small; the lifespan and safety difference is large.

• Continuous duty (24/7 or 3-shift): Wear and bearing fatigue accumulate fast. Add 25 to 50% to required rating, or step up one stocked size.
• Towed at speed (above 3 mph): Cornering and shock loads spike. Step up one size and spec sealed precision bearings on wheel and swivel.
• AGV / motorized tugger: Shock from acceleration, deceleration, and turn-in-place. Always spec kingpinless and step up one size.
• Crosses expansion joints, dock plates, or grating: Shock spikes 2 to 4x dynamic. Step up wheel size and rated capacity.
• Carries a known shock load (drop, impact, lift assist): Calculate shock load explicitly. See our Shock Load Rating article for the math.
• Outdoor or temperature extreme: Pneumatic for outdoor; phenolic or high-temp poly for hot. Verify temperature rating on the spec sheet.

Specing up is also the right call when your cart will outlive its first use case. We see customers buy a cart for 1,200 lb today and load it to 2,000 lb within 18 months as the operation grows. If you can afford the headroom on day 1, build it in. The next caster sourcing event you will not have to do is the cheapest one. See the full duty-cycle decision logic in our Are Casters Universal? Compatibility & Replacement guide and the Industrial Casters Complete Guide.

Frequently asked questions #