How to Build a Jeans Size Chart for OEM Production in China

1. Establish the Base Size and Define Every Measurement Point

Begin with the intended customer, fit block, size range, and selling market. A slim jean, relaxed jean, and rigid straight jean should not share a chart merely because their size labels match. Select a reference size supported by a fit-approved sample or a clearly identified development garment. State whether the figures describe body dimensions or finished garment dimensions; an OEM production chart normally needs the latter. Use either centimeters or inches consistently, and define rounding rules if conversion is necessary. Record fabric construction, stretch characteristics, waistband design, and intended wash beside the chart so the factory can identify the conditions under which the targets apply.

Create a point-of-measurement list with codes that appear on both the spreadsheet and annotated garment drawings. Typical points include waist, hip, front rise, back rise, thigh, knee, leg opening, inseam, and outseam. For each point, define where the tape starts and ends, whether the garment is fastened, and whether the tape follows a seam or a straight line. Locate hip, thigh, and knee measurements from named reference points rather than relying on visual judgment. Specify whether the waist is measured flat across or along the waistband, and identify any relaxed or extended measurement separately. Never assume that a flat width and a full circumference are interchangeable without an explicit conversion rule.

2. Build Grading Rules Around the Approved Fit

Once the reference size is established, build a grading table that shows how each measurement changes between adjacent sizes. Grade rules are design decisions, not universal factory defaults. Waist and hip may need different increments, while rise, thigh, knee, and leg opening require their own progression to preserve the intended silhouette. Keep inseam constant only when the product specification actually calls for one length across those sizes. If you offer separate waist and length combinations, show that structure clearly instead of forcing every variant into a single linear sequence. Ask the pattern team to flag any increments that create construction problems or undermine the fit block.

Check the chart mathematically before requesting samples: each size should reconcile with the approved base size and the stated increments. Then check it physically, because an internally consistent spreadsheet does not prove that the pattern fits. Review the reference size and representative sizes near the ends of the range, with additional checks where the grading progression changes. Compare balance, seat coverage, crotch comfort, waistband position, and leg shape as well as tape measurements. If a fit correction changes the base pattern, review every affected size rather than adjusting one cell and leaving the rest untouched. Record the revised grade rule and confirm which pattern version the factory will use.

3. Validate Wash Shrinkage Allowances and Set Tolerances

Define the production chart's acceptance stage explicitly, preferably as the finished garment after the specified production wash and agreed conditioning period. Denim can change differently in length and width, and the result depends on fabric, construction, processing, and finishing conditions. Ask the OEM to measure development garments before and after the intended wash, using matching measurement methods and a recorded process. Separate factory wash effects from any consumer laundering requirement; they are not automatically the same test. Do not insert a generic shrinkage percentage and assume it applies to every measurement. Use trial results to establish working allowances, then verify those allowances on the next sample or pilot run.

For a simple measured direction, an initial calculation can be pre-wash dimension equals finished target divided by one minus the expected shrinkage rate. For example, a 100 cm finished target with 3 percent shrinkage gives about 103.09 cm before washing. This is only a starting estimate, not a complete pattern specification: seam allowances, waistband behavior, garment construction, and process variation still require factory validation. Set tolerances separately for each finished measurement, considering fit sensitivity and demonstrated process capability. State whether limits are symmetrical or directional. Tolerance is an acceptance boundary, not permission to deliberately shift the entire order toward one limit, and it must not be used to hide an incorrect shrinkage allowance.

4. Issue a Controlled Size Chart to Your China Denim OEM

Send one coordinated package containing the size chart, measurement diagrams, grade rules, fabric information, wash reference, construction details, and sample comments. Give the style a unique identifier and put a revision number and date on every controlling document. A spreadsheet is useful for calculations, while a matching PDF helps preserve the approved layout; identify which file controls if they disagree. Use plain English and consistent measurement codes, with bilingual notes where useful to the production team. Ask the factory to confirm the measurement methods, finished targets, proposed tolerances, and unresolved questions in writing. A brief acknowledgment is not enough if important assumptions about waist measurement or wash stage remain unclear.

Plan sampling and bulk approval as separate decisions. The MOQ is 100 pcs; confirm how any proposed size, color, and wash breakdown affects order acceptance and costing. Samples take approximately 7 days once the brief and materials are confirmed, while bulk lead time depends on quantity and the confirmed production requirements. At sample review, request actual measurements against target for each relevant point, together with fit observations and wash details. Approve corrections in a consolidated revision instead of scattering instructions across chat messages. Before bulk cutting, confirm the controlling chart and pattern version. During production, review measurements from representative sizes and relevant wash batches under an agreed inspection plan rather than relying only on the development sample.

Questions before sampling