What a Jeans Tech Pack Must Contain
The aim of a jeans tech pack is to remove interpretation. Two factories reading the same pack should produce samples that look and measure alike, and a quote built on the pack should hold when bulk begins. The general principles are covered in our guides to making a clothing tech pack and why factories need one; this page adds the denim layer on top.
If you do not yet have a pack, start with a reference pair you like and write down what you would change. That approach produces a better pack than starting from a blank page, because every measurement and detail is anchored to a real garment.
How a Jeans Tech Pack Differs from a Standard One
Compared with a T-shirt or hoodie, jeans are a construction-heavy garment with a washing process that changes size and appearance. Four differences shape the document.
- Wash changes everything. Measurements must be given before and after wash, and the wash itself needs a standard.
- Many small components. A pair of jeans has hardware, patches, pocket bags, labels, thread and interlining, each with a specification.
- Seam types matter. The seam construction affects strength, appearance and cost.
- Fabric is the product. Weight, composition, stretch and shrinkage define how the jeans wear.
Construction Details and Stitch Specification
Jeans construction details are the part new brands most often leave out, and the part experienced factories most often have strong defaults for. If the pack is silent, the factory uses its standard, which may not be your standard. Specify stitch type, stitch density and thread for each major operation.
Stitch types are usually named by their numeric class: a 301 lockstitch for much of the topstitching, a 401 chain stitch for operations such as felling and waistbands, a 504 three-thread overlock for edge finishing and a 516 safety stitch where a combined seam and overlock is used. The density is stated as stitches per inch, and denim topstitching commonly sits somewhere in the range of about 8 to 12 depending on thread weight and look. Confirm with your supplier what suits your fabric and style, and avoid copying a number from another pack without checking it.
| Operation | What to state | Example entry (illustrative) |
|---|---|---|
| Main topstitching | Stitch type, thread, colour, stitches per inch | Lockstitch, contrast gold thread, colour reference attached, 9 SPI |
| Inseam and outseam | Seam type and finish | Felled seam, chain stitch, specify single or double row |
| Back pocket | Shape, size, placement, decorative stitch | Dimensions from yoke seam and side seam, with a template |
| Fly and zip | Fly shape, J-stitch, zip length and finish | Metal zip, antique brass finish, length by size |
| Waistband | Width, curve, interlining, belt loops | Number of loops, width and placement from side seams |
| Reinforcement | Bartacks, rivets, stress points | Bartack at belt loops and fly base; rivets at pocket corners |
| Hem | Hem type and depth, chain-stitch or raw edge | Single turn, 2 cm depth, with or without roping effect |
Where the look is important, add a close-up photo of the reference detail with an arrow and a note. Pictures reduce misreading more than long paragraphs do. The jeans quality inspection checklist shows which of these details are later checked at inspection, so describe them in a form that can be verified.
The Jeans Measurement Spec
A jeans measurement spec lists the points of measure, a base size and a grade, together with tolerances. For jeans, the key points include waist, seat or hip, front rise, back rise, thigh, knee, leg opening and inseam. Many buyers also include pocket sizes, fly length, waistband height and belt loop placement. A detailed treatment of points, grading and vanity sizing sits in our jeans size chart and measurement spec guide, and the jeans rise guide explains how to define rise precisely.
The crucial denim point is that every critical measurement should be given at two stages: before wash and after wash. Denim shrinks and relaxes during washing, so a measurement without a stage is ambiguous. State which stage each tolerance applies to and which stage is the customer-facing size. For general grading rules, refer to the garment grading guide.
The Fabric Specification
The fabric section should give the mill and article reference if known, the weight in ounces per square yard with the equivalent GSM, the composition, the stretch level, the cut width and the shrinkage target. Weight is explained in the denim fabric weight guide, and composition options in the denim fabric composition guide.
Shrinkage deserves its own line. State a target for length and width after the agreed wash and test method, and describe how leg twist, or skewing, will be controlled. The denim shrinkage guide explains why this matters and how tolerances are set. Where fabric is not yet selected, write a performance brief instead: the weight range, handle, stretch and recovery you want, and the price ceiling for fabric per metre.
The Denim Bill of Materials
The denim BOM lists every component with its specification, supplier reference where known, colour, placement and quantity per garment. A short BOM entry is a vague one. Compare these two lines for the same item.
- Button: metal, silver
- Thread: matching
- Pocketing: white cotton
- Tack button, 17 mm, brass base, antique nickel finish, logo engraved, 1 per garment
- Topstitch thread: reference and colour code attached, with a swatch card
- Pocketing: poly-cotton, weight and width stated, printed with artwork file reference
Trim failure is a common cause of returns, so specify strength requirements where relevant and ask the supplier for test evidence. The denim trims and hardware guide explains the main components and tests. Remember that hardware finish should suit the wash, and that a bright metal finish on a vintage-style wash will look out of place.
The Wash Standard
The wash section is the most frequently under-written part of a jeans pack. Include the wash name, a reference photograph, a physical wash sample, a short description of the process route and the shade tolerance. If the wash has distressing, state where, how much and how it should look, and attach a placement diagram. If the wash uses special processes such as laser or ozone, record those too.
Physical standards beat photographs, because screens and lighting change colour. Agree who holds the master standard, and request that bulk is compared against it under consistent light. The types of denim washes guide gives you the vocabulary to describe a wash, and the how to get jeans manufactured guide shows where wash approval sits in the process.
A Worked Example: Pre-Wash and Post-Wash Values
The table shows how a measurement block might look for one size of a straight-leg jean. Every number is an example to illustrate the layout, not a recommendation for your fit, and your own figures should come from a reference pair and the fabric's actual shrinkage.
| Point of measure (size 32, cm) | Pre-wash | Post-wash target | Tolerance |
|---|---|---|---|
| Waist, relaxed, flat | 82.0 | 81.0 | plus or minus 1.0 |
| Seat, 15 cm below waist | 102.0 | 101.0 | plus or minus 1.0 |
| Front rise, including waistband | 27.0 | 26.5 | plus or minus 0.5 |
| Thigh, 2.5 cm below crotch | 62.0 | 61.0 | plus or minus 0.5 |
| Leg opening | 38.0 | 37.5 | plus or minus 0.5 |
| Inseam | 83.0 | 81.5 | plus or minus 1.0 |
Notice that the pre-wash values are larger than the post-wash values, because the pattern has been cut with a shrinkage allowance. The inseam shows the biggest change in this example because length usually shrinks more than width in rigid and low-stretch denim. If the factory delivers a post-wash inseam of 80 cm against a 81.5 cm target, the garment is outside tolerance even if the pre-wash measurement was perfect, and that is exactly the situation a two-stage spec is designed to prevent.
Add the method as well as the number. State where each point is measured, whether the garment is laid flat or on a measuring table, how long it rests after washing and drying before it is measured, and the humidity or conditioning the lab uses if relevant. These details look pedantic until a dispute arises, at which point they decide who is right.
How to Build the Pack: A Practical Sequence
- 1Choose a referencePick the closest existing pair and measure it fully.
- 2Draw and annotateCreate flat drawings, mark every construction detail.
- 3Fill the specsWrite the measurement spec, fabric, stitch and BOM tables.
- 4Add the washAttach the wash reference and tolerance notes.
- 5Review with the factoryWalk through the pack, resolve questions, note changes.
- 6Version and lockNumber the version, date it and track every revision.
Version control deserves attention. Number each issue of the pack and keep a change log, so the factory and you can tell which version a sample was built from. When a comment is made on a sample, reference the pack section it relates to. The garment sampling guide explains how sample rounds interact with the pack, and the ability to trace each comment to a revision saves arguments later.
Common Jeans Tech Pack Mistakes
- No pre-wash and post-wash measurements. Sizes become arguable.
- Missing thread and stitch details. The factory defaults to its own.
- Vague trims. Words like silver, matching or standard are not specifications.
- A wash described only in words. Always provide a physical standard.
- Mixing metric and imperial without saying so. State the unit on every table.
- No shrinkage target. The garment can pass inspection and still fit wrongly after the first wash.
- Several versions in circulation. Keep a single current version and log changes.
Jeans Tech Pack Checklist
- Flat drawings with front, back, side and detail views
- Measurement spec with base size, grade and tolerances
- Pre-wash and post-wash values for critical points
- Fabric reference, weight, composition, stretch and shrinkage target
- Stitch types, stitches per inch and thread references
- Complete BOM with finishes, sizes and placements
- Wash standard, reference sample and tolerance
- Labels, hangtags, packing and carton instructions
- Version number, date and change log
Jeans Tech Pack Support with Ruhrose
Not every brand arrives with a finished pack. The Ruhrose development team can work from a reference pair, a sketch or an incomplete pack, completes the construction and measurement detail and returns it for your approval. Development and production take place in Bangladesh with UK buyer support, so questions get answered in plain terms and in your working day.
Production starts from 500 pieces per style and colour. To turn your idea into a pack a factory can quote, start a product enquiry and share a reference pair, a sketch or your current pack. Related reading includes the private label jeans launch guide.