To estimate the capacity needed per caster, add the cart’s empty weight and maximum payload, divide by the number of casters assumed to share that weight, and apply an application factor supported by the caster manufacturer’s guidance. The tables below show calculated load-sharing values—not universal product ratings.
The critical distinction is between the number of casters installed and the number effectively supporting the load. Even when every wheel touches the floor, the loads may not be equal. Blickle’s load-capacity guidance specifically notes that individual wheel or caster loads can vary on equipment with four or more supports.
Calculate the Loaded Cart Weight First
Use the maximum intended operating weight, not payload alone:
[
W=E+P
]
Where:
- (W) = total loaded cart weight.
- (E) = empty cart weight, including permanently installed equipment and accessories.
- (P) = maximum payload, including containers, fixtures, or attachments not already included in (E).
For preliminary equal-sharing calculations:
[
R=\frac{W}{n_s}\times S
]
Where:
- (R) = calculated required rating per complete caster assembly.
- (n_s) = number of casters assumed to share the load equally in the scenario being evaluated.
- (S) = dimensionless application factor selected for the documented operating conditions.
This follows the calculation structure described in Blickle’s product-selection guidance: equipment weight plus additional load, divided by supporting wheels or casters, then multiplied by an application-dependent safety factor. The arithmetic is applicable only when the assumed load sharing is reasonable for the equipment.
The tables use lb in the customary US catalog weight-capacity sense. Their kg values are equivalent supported masses, not force values. The conversion used is (1\text{ lb}=0.45359237\text{ kg}). For a force calculation, distinguish lbf from lb mass and N from kg; do not enter a kg value into an input labeled lbf.
Capacity Table When All Casters Share the Load Equally
This table assumes every installed caster carries an equal share and uses (S=1.00). It provides a baseline for comparison, with no additional application margin.
Each capacity cell shows lb per caster, followed by equivalent kg in parentheses. Values are rounded up to the next whole lb; kg values are converted from those displayed lb values and rounded to one decimal place.
| Total loaded cart weight, lb | 3 equally loaded casters, lb (kg) each | 4 equally loaded casters, lb (kg) each | 6 equally loaded casters, lb (kg) each | 8 equally loaded casters, lb (kg) each |
|---|---|---|---|---|
| 400 | 134 (60.8) | 100 (45.4) | 67 (30.4) | 50 (22.7) |
| 800 | 267 (121.1) | 200 (90.7) | 134 (60.8) | 100 (45.4) |
| 1,200 | 400 (181.4) | 300 (136.1) | 200 (90.7) | 150 (68.0) |
| 1,600 | 534 (242.2) | 400 (181.4) | 267 (121.1) | 200 (90.7) |
| 2,000 | 667 (302.5) | 500 (226.8) | 334 (151.5) | 250 (113.4) |
| 3,000 | 1,000 (453.6) | 750 (340.2) | 500 (226.8) | 375 (170.1) |
For example, the four-caster entry for a 1,200 lb cart is 300 lb per caster. That is the average load under the stated equal-sharing assumption—not a recommendation to buy four 300 lb casters.
Adding casters reduces the calculated average only if the added supports actually carry load. A six- or eight-caster arrangement cannot be treated as evenly loaded merely because that many casters are installed.
What Changes When One Caster Is Assumed Unloaded?
A one-caster-unloaded scenario replaces the installed count (N) with (N-1):
[
R=\frac{W}{N-1}\times S
]
The following table shows that scenario with (S=1.00). It still assumes equal sharing among the remaining supports and contains no separate allowance for impact, temperature, speed, or other operating conditions.
| Total loaded cart weight, lb | 4 installed, 3 sharing: lb per caster | 6 installed, 5 sharing: lb per caster | 8 installed, 7 sharing: lb per caster |
|---|---|---|---|
| 800 | 267 | 160 | 115 |
| 1,200 | 400 | 240 | 172 |
| 2,000 | 667 | 400 | 286 |
| 3,000 | 1,000 | 600 | 429 |
These are calculated scenarios, not manufacturer capacity ratings or proof that losing one support is the worst possible condition. In particular:
- Three loaded supports do not necessarily carry one-third of the weight each.
- An off-center payload can load one caster more heavily than the others.
- Center-mounted wheels, unequal mounting heights, frame deflection, or an equalizing suspension can change which supports carry load.
- A floor transition can change the support pattern while the cart moves.
Use (N-1) only when it represents a defensible screening case for the actual layout. Do not automatically extend a four-caster assumption to every six- or eight-caster cart.
Where load distribution is uncertain, determine individual support reactions from the equipment geometry and loading arrangement, or obtain measurements using suitable wheel-load scales under representative conditions. A stationary measurement establishes only that stationary condition; it does not measure peak loads during impact, turning, or floor transitions.
Apply an Application Factor Without Hiding the Assumptions
The factor (S) is not a universal constant. It must correspond to the manufacturer’s rating basis and the deviations expected in service.
For example, Blickle’s load-capacity guidance relates its recommended factors to manual or powered movement, indoor or outdoor use, and obstacle height relative to wheel diameter. It also states that those factors do not account for tread wear. Those recommendations belong to that manufacturer’s guidance; they should not be presented as universal factors for every caster series.
Record what the factor covers. If reducing the support count already represents one unloaded caster, do not add another unexplained “uneven-floor factor” for the same assumption. Conversely, reducing the support count does not account for shock loading or unequal loads among the remaining casters.
Worked Example: A 1,200 lb Cart With Four Casters
Assume the following hypothetical screening inputs:
| Input | Value | Basis |
|---|---|---|
| Empty cart weight | 150 lb | Assumed example |
| Maximum payload | 1,050 lb | Assumed example |
| Total loaded weight | 1,200 lb | Empty cart plus payload |
| Installed casters | 4 | Assumed layout |
| Sharing casters | 3 | One-unloaded-caster scenario |
| Application factor | 1.25 | Illustrative assumption, not a general recommendation |
The calculation is:
[
R=\frac{150+1{,}050}{3}\times1.25
=500\text{ lb per caster}
]
The equivalent supported mass is:
[
500\times0.45359237=226.8\text{ kg per caster}
]
Under these assumptions, the screening requirement is 500 lb per complete caster assembly. A candidate would need an applicable published assembly rating of at least that value after any manufacturer-required adjustments.
The calculation does not establish that three supports will share the load equally or that a factor of 1.25 is adequate for the application. Those assumptions must be resolved before using the result for purchasing.
For a weight between table rows, calculate directly from the actual weight rather than rounding down to a lower row. Apply the factor to the unrounded calculation, then round the final requirement upward.
Compare the Result With the Correct Manufacturer Rating
A wheel rating and a complete caster assembly rating are different specifications. A replacement wheel’s capacity alone does not establish the capacity of the fork, axle, swivel section, mounting connection, or assembled caster.
Use the following distinctions when recording candidate products:
| Rating or record | What it represents | What to confirm before comparison |
|---|---|---|
| Wheel-only rating | Capacity published for the specified wheel configuration | Exact wheel part number, bearing, bore, and rating conditions; do not substitute it for an assembly rating |
| Complete caster assembly rating | Capacity published for the specified assembled caster | Exact assembly part number, wheel, bearing, bracket, mounting type, and relevant options |
| Dynamic rating | Capacity associated with the manufacturer’s stated rolling test or operating conditions | Speed, surface, obstacles, duty, temperature, and any restrictions |
| Static rating | Capacity for the manufacturer’s stated stationary loading conditions | Loading duration, temperature, and applicable deformation criteria |
| Source record | Evidence supporting the rating being used | Datasheet or catalog identifier, revision/date if supplied, source unit, rating type, and applicable notes |
Blickle distinguishes dynamic load capacity from static load capacity and notes that its static evaluation includes tread flattening after a specified period. A higher stationary capacity is therefore not a substitute for an applicable rolling rating.
For a cart that moves under load, compare the calculated requirement with an applicable dynamic rating. If it also remains loaded while parked for long periods, check the manufacturer’s static limits separately.
Preserve the original rating and unit in the purchasing record. A converted kg or lb value is a display aid; conversion does not change the rating’s test conditions or extend its application.
Check Whether the Published Rating Matches the Service
A capacity number is meaningful only with its operating conditions. Colson Group’s Wheel Selection Guide states that its published ratings assume smooth floors, rails, or tracks without obstructions or severe shock loads, with properly lubricated bearings. It also identifies temperature and contamination as conditions that can reduce capacity and performance.
For each candidate assembly, establish whether the published rating applies to:
- Manual movement or powered towing.
- The intended speed and frequency of movement.
- Floor joints, thresholds, debris, and other obstacles.
- Operating and storage temperatures.
- The actual bearing, tread, and assembly configuration.
Do not use a manual-operation rating as evidence of towing suitability. Colson explicitly distinguishes manual operation from powered movement and calls for specifically designed casters and application recommendations for mechanically moved equipment.
Where manufacturer guidance requires a capacity reduction, compare the calculated requirement with the adjusted applicable rating—not the headline catalog number. Without a published reduction or application recommendation, a generic factor cannot establish suitability.
Use the Calculators With the Same Inputs and Boundaries
The Caster Load per Wheel Calculator accepts loaded cart weight, caster count, an equal-sharing or one-caster-unloaded option, and a user-selected safety factor. Use the same assumptions as the table or example when comparing results. Its published limitations state that off-center loading, impact, towing, and static-versus-dynamic rating differences are not modeled. A selected factor does not turn those effects into calculated support reactions.
The How Many Casters Do I Need? Calculator works backward from load and candidate caster capacity to a preliminary count, with a selectable one-unloaded-caster allowance. Its load and capacity inputs are labeled lbf. The resulting count does not establish load sharing, choose the mounting layout, or verify the frame.
Before ordering, retain the loaded weight, installed count, assumed sharing count, application-factor basis, calculated per-caster requirement, and exact manufacturer rating used for comparison. The tables establish only a load-sharing estimate; they do not determine the cart’s rated payload, mounting strength, stability, braking capability, or ease of movement.