To measure the size of a welded round-link chain, first identify the chain type. Use a caliper to measure the diameter of the steel forming a link, then its clear inside length and inside width. Compare all three readings with the drawing and specification for that particular chain.
A single diameter reading may tell you the approximate nominal size, but it does not establish the chain grade or working load limit (WLL). If the chain is a roller chain or a stud-link anchor chain, check its own measurement drawing before applying the same method.
What Measurements Define a Chain Link?
For the Grade 80 short-link lifting chain shown in Powerful Machinery’s catalogue, D is nominal material diameter, A is internal length, and B is internal width. These letters describe that drawing. Check the column names every time you move to another product table: the G100 drawing in the same catalogue labels internal length L, external width B, and internal width b.
| Dimension | Where to measure | Why it matters |
| Material diameter (D) | Across the round bar forming the link, away from the weld | Identifies the nominal bar size when checked against a product specification |
| Inside length (A in the G80 table) | Between the inner surfaces at the two ends of the link, along its long axis | Identifies link geometry and helps compare the link with its specification |
| Inside width (B in the G80 table) | Between the inner surfaces of the two sides, across the short axis | Shows the clear opening; important for compatible fittings |
| Outside length and width | Across the outermost edges of the link | Use for overall clearance or when the product drawing specifies external dimensions |
| Pitch | As defined by the chain’s own drawing or standard | Different chain constructions use different measurement points |
Inside length is not overall outside length. Inside width is not overall outside width. A link’s two walls add to its external span, and bends, welds, and tolerances can affect the result. Do not replace a stated catalogue dimension with a dimension measured at a different pair of contact points.
Tools You Need
Use a clean digital or vernier caliper with external jaws for material diameter and suitable internal jaws for the clear opening. Check that it closes to zero and record whether your readings are in millimeters or inches. A ruler can give a rough check on a large link, but it is a poor substitute when a catalogue distinguishes nearby sizes by small differences.
Keep the manufacturer’s product drawing or original specification beside you; a measured number without a named dimension is hard to use.
How to Measure a Welded Round-Link Chain With a Caliper?
Step 1: Identify the Chain Type
Look at the construction before opening the caliper. This procedure is for individual welded round links. A roller chain has pins, rollers, and plates; an anchor link may have a central stud. Note any legible product marking, identification tag, chain grade, and standard, but treat those as separate information to verify.
If you cannot establish the chain type, record the dimensions and ask the supplier to identify the product before ordering a replacement or using it for lifting.
Step 2: Clean the Measurement Area
Wipe away loose dirt and thick grease where the jaws will touch. Choose accessible links that are not obviously bent, heavily corroded, or locally worn if your purpose is to identify the original nominal size. If damage is visible, note it separately; a clean reading does not make a damaged lifting chain fit for service.
Step 3: How to Measure Chain Diameter (D)
Place the caliper’s external jaws squarely across a sound, round section of the link. Close them gently and read the material diameter. Avoid the weld, its enlarged area, flattened contact surfaces, and obvious wear grooves when estimating nominal size.
Repeat on more than one sound section and record the readings before comparing them with the catalogue. This nominal-size check is different from a wear inspection, which uses the measurement points and limits specified for the product.
Step 4: Measure the Inside Length
Set the internal jaws between the curved inner ends of the link along its long axis. Expand them until both tips touch the inside surfaces without forcing the tool. Record the clear inside-to-inside distance. Do not measure outside end to outside end and call it “inside length.” If the link is hard to access while interlocked, select an exposed link or use a suitable gauge and the manufacturer’s measurement method.
Step 5: Measure the Inside Width
Turn the caliper across the short axis and measure the clear gap between the two inner sides. Use the contact points shown in the product drawing; a weld bulge can distort a reading taken at the wrong position. Record this inside width separately from any outside-width reading. For a stud-link anchor chain, use its own drawing rather than treating the gap beside the stud as the width of the full link.
Step 6: Record and Compare the Readings
Write down the chain type, measurement locations, material diameter, inside length, inside width, units, and the drawing you used. Check several representative links when matching replacement parts. Compare each value with the matching dimension and tolerances in the applicable specification.
If readings vary markedly, check for wear, deformation, mixed chain, or incorrect identification. Diameter alone cannot establish Grade 80, Grade 100, or a WLL.
How Is Chain Pitch Measured?
First ask which kind of chain and which specification uses the word “pitch.” There is no safe, universal instruction to measure every industrial chain from the center of one link to the center of the next. Use the dimension line and definition printed for the chain you have.
| Chain type | Pitch or length check |
| Welded round-link chain | Many specifications give an internal link length or nominal link pitch. Identify its exact endpoints in that product drawing; do not substitute a roller-chain pin measurement. |
| Roller chain | Pitch is the center-to-center distance between adjacent pins. Also check roller diameter and width between inner plates. |
| Anchor chain | Check the specified link length/pitch, diameter, and width against the applicable anchor-chain drawing, including whether it is stud-link or studless. |
For a roller chain, measuring across several pin intervals and dividing by the number of pitches can reduce the effect of a single placement error. That method belongs to pin-connected chain and does not redefine the dimensions of a welded round link.
Measuring Different Types of Chain
Welded and Lifting Chain
For a welded lifting chain, record the material diameter and the specified internal link dimensions, then compare them with the correct grade-specific product data. For capacity selection, consult the lifting chain sizes alongside the actual product identification and sling configuration.
For the grade itself, check the marking and documentation; our guide to identifying chain grade covers that separate task. Chain measurement alone cannot certify a lifting assembly.
Stud-Link and Studless Anchor Chain
Start with the round-bar diameter, then check the applicable link dimensions and whether a central stud is present. A stud changes the open space and the contact points available to your caliper. Use the relevant manufacturer or standard drawing for that anchor-chain construction rather than a lifting-chain chart.
Our dedicated guide explains how to measure anchor chain size in more detail. ISO 1704 addresses stud-link anchor chains; EN 818-2 covers Grade 8 short-link chain for lifting and should not be described as a marine anchor-chain standard.
Roller Chain
A roller chain uses plates, pins, bushings, and usually rollers. Measure the center-to-center distance between adjacent pins for pitch, then check the roller outside diameter and width between inner plates against its specification. Neither roller diameter nor inner-plate width corresponds to the bar diameter or inside opening of a welded link.
How Wear Changes Chain Measurements?
In-service wear can reduce bar diameter, while deformation or elongation can change link dimensions. Corrosion can also interfere with a reliable reading. Record damaged areas separately; do not average them into a nominal-size measurement. A competent person must assess lifting or anchor chain condition under the applicable inspection procedure. This measurement guide does not set a universal wear or discard limit.
Common Chain Measurement Mistakes
- Measuring across the weld and using its enlarged section as the nominal bar diameter.
- Taking one reading from a worn link and treating it as the original product size.
- Confusing clear inside length or width with the link’s outside dimensions.
- Assuming that the same letter names the same dimension in every catalogue drawing.
- Applying pin-to-pin roller-chain pitch to a welded or anchor chain.
- Treating a nominal diameter as proof of chain grade, WLL, or fitness for lifting.
Chain Size Reference Example From the Catalogue
Powerful Machinery’s DIN EN 818-2 Grade 80 lifting-chain table lists one nominal size as D = 8 mm, internal length A = 24 mm, and internal width B = 11.5 mm. Read this as three different dimensions of the same specified link, not as three interchangeable ways to state its size.
The G100 short-link table also has an 8 mm nominal entry, but labels its internal length L = 24 mm, external width B = 27.5 mm, and internal width b = 11.5 mm. This example shows why you must read the column heading, not just the letter. It does not establish interchangeability, lifting capacity, or compatibility of two chain products.
Once you have the dimensions and product identification, explore the relevant lifting chains and ask for the current model drawing if you are matching replacement chain or fittings.
FAQs
How Do You Measure Chain Link Size?
For a welded round link, measure its material diameter, clear inside length, and clear inside width with a caliper. Compare each reading with the corresponding dimension on the exact product drawing.
Is Chain Size Measured by Diameter?
Diameter is a common nominal size for welded round-link chain, but you also need the link length and width to identify its geometry. Diameter alone does not tell you the grade or WLL.
How Do You Measure Chain Diameter?
Measure across the sound, round portion of the steel link with the caliper’s outside jaws. Avoid the weld and visibly worn spots when identifying the original nominal size; take readings on several sections.
How Do You Measure the Inside Width of a Chain Link?
Place the caliper’s internal jaws across the short axis between the two inner sides of the link. Expand gently and record the clear gap. An outside-width measurement is a different dimension.
How Do You Measure Chain Pitch?
Identify the chain type first. Roller-chain pitch runs from the center of one pin to the center of the next; welded and anchor chains must be measured according to their own dimensional drawings.
How Do You Measure Lifting Chain Size?
Measure the bar diameter and the internal dimensions specified for that lifting chain. Confirm its grade, identification, and rated assembly data separately before any lifting use.
How Do You Measure Anchor Chain Size?
Measure the link material diameter and the dimensions named on the applicable anchor-chain drawing. Check whether the link has a stud, since that changes the clear opening and the correct measurement points.
Can Two Chains Have the Same Diameter but Different Link Dimensions?
Yes. Link patterns and product specifications can differ even when the round-bar diameter is the same. Record the inside length and width and compare the full construction before ordering a replacement.
