Your factory can't see the jeans in your head.
What they can see is a mood board, a couple of screenshots and a WhatsApp voice note that starts "so basically, think 90s but not too 90s". They'll make something from that, but it might not be the thing you were picturing.
That's what a tech pack is for. It's the instruction manual for your product, telling the factory exactly what to make, what it's made from, how it's put together, what it should measure and what it should look like when it comes out of the wash.
If something isn't in the tech pack, the factory has to guess. Factories are very good at guessing, they're just not guessing for your customer.
Why denim tech packs are a bit different
A t-shirt tech pack and a jeans tech pack have a lot in common, but denim has a few extra ways to go wrong.
Your jeans get sewn and then they get washed, and the wash can change the colour, the handfeel, the measurements and the fit. So a denim tech pack has to cover what the jeans look like after the laundry has had its way with them, not just what comes off the sewing line.
Then there's the hardware: rivets, shank buttons, zips and leather patches. That's a lot of little parts from a lot of suppliers, and a lot of chances for someone to swap in the cheaper version.
So here's what I put in mine.
1. The front page
The basics, all in one place:
The design, so everyone can see at a glance what we're making
Style name and number
Season
Factory and supplier details
Base size
Fabric
Wash name
Date and version number
Version control sounds boring, and it is, but it's also the thing that stops your factory making sample 3 from the tech pack you sent for sample 1.
2. Inspiration
This is where your mood board and reference images go. What's the vibe and what are you benchmarking against? Is there a vintage pair you love the rise on, or a competitor's wash you want to get close to?
Reference images are really useful, but they need context. "Like this" isn't an instruction, whereas "like this through the thigh and knee, but with a higher rise" is.
3. Technical flats
These are clean front and back line drawings of the jeans, laid flat, with no models, no styling and no attitude, just the garment.
Flats show the factory every seam, pocket, yoke, belt loop, rivet and bartack. If there's a coin pocket or the back pockets are angled, it needs to be on the flat, and if it's not on the flat, don't be surprised when it's not on the sample.
I add close-up callouts for anything fiddly, like the fly, the waistband join or the pocket bag.
I always share the .ai file for the flats too. Designs evolve during development, and you should be able to update your own drawings without having to come back to me every time.
4. Construction details
This is where you tell the factory how to put the jeans together. I do a page for each area of the garment, showing:
Seam types. Is the inseam felled or overlocked? Is the outseam a safety stitch? Is the back yoke flat-felled?
Stitch types and stitches per inch. Is it a chain stitch hem or lockstitch, and how dense?
Thread. Colour, weight and whether the topstitching is contrast or tonal. Denim topstitching is as much a design detail as a construction one, so this really matters.
Bartacks and rivets. Exactly where they go and how many.
Pocket construction. Pocket bag fabric, facing depth and how the coin pocket is attached.
You can see examples of construction pages from three of my tech packs over on my portfolio.
5. Bill of materials
The BOM is the shopping list, covering every single component that goes into the jeans:
Denim. Mill, quality reference, composition, weight in oz, rigid or stretch, and shrinkage
Pocketing. Fabric and colour
Thread. Brand, ticket and colour for every thread used
Zip or buttons for the fly. Supplier, size and finish. If you want a YKK zip, say YKK. (And yes, counterfeit branded zips are a real thing. I've talked about that in my post on why jeans get returned.)
Shank button and rivets. Size, finish, and whether they're branded or plain
If two components look similar, put a photo or a reference number next to them, because "antique brass rivet" means different things to different suppliers.
Don't panic if you don't have all of this at the start. You probably won't, and that's fine, because it all gets added in as you start sourcing.
6. Labels and packaging
Labels get their own section, because it's not just about what they say, it's also about where they go.
Back patch. Material, size, artwork and exactly where it sits on the waistband
Main label and size label. What they say, what they're made of and where they're sewn in
Care label. Composition, care instructions, country of origin, and which seam it goes in
Placement. Every label marked on the flats with measurements, so the factory isn't left to decide
Packaging. Swing tags, how they're attached, bags and folding instructions
If you've ever had a care label land right where it scratches the small of your back, you'll know why placement matters.
7. Wash and finish
This is the big one for denim, because it's where you tell the factory what the finished jean should actually look like. I want to see:
The wash standard. A physical reference if you have one, or a really clear photo if you don't.
The finishing processes. Is it a stone wash, enzyme, bleach, tint or rinse? Are there whiskers, honeycombs, abrasion or damage, and if so, where on the leg and how heavy?
Placement. If there's a rip, where exactly is it? Mark it on the flat with measurements.
Shade tolerance. How much variation is acceptable between pairs and between production runs.
And if you've got more than one wash on the same style, remember they might not fit the same, because different washes can shrink differently. There's more on that in my returns post too.
8. Points of measure
Points of measure, or POMs, are the list of measurements that define the jeans: waist, hip, front rise, back rise, thigh, knee, leg opening, inside leg, pocket sizes and placements, and so on.
Every measurement gets a code, and that code is used on the spec so everyone knows exactly which measurement we're talking about.
Rather than squeezing a POM page into every tech pack, I send my How to Measure Jeans guide with each one. It shows every point of measure with a drawing and a full description of how to take it, and the codes match the spec. So whoever picks up the tape measure, whether that's you, the factory or me, is measuring from and to the same place.
This might sound like overkill until you discover your factory measures the thigh 2.5cm below the crotch and you measure it 5cm below. Suddenly your sample is "out of spec" when nobody's actually done anything wrong.
9. Size spec and grading
The spec sheet gives the measurements for your base size, plus a tolerance for each point of measure, which is the amount of variation either side you'll accept in production.
Then there's the grading, which is how every measurement grows or shrinks across your size range. I've written a whole post on grading so I won't repeat myself here, but please don't just let the factory slap a standard grade on without checking it.
If your brand has blocks, the tech pack should also reference which one the style was developed from.
10. Fit comments
The tech pack doesn't stop once you've sent it.
Every time a sample comes in, I add a page of fit comments, with photos of the sample on the fit model from the front, side and back, annotated with what's working and what isn't. Then come the measurements: what we asked for, what we got, and what we want next time.
Clear fit comments can be the difference between three rounds of sampling and six. "The fit's a bit off" won't get you anywhere, but "Front rise is 1cm short, pulling at the crotch. Lengthen front rise by 1cm, keep back rise as is" will.
11. Approvals and sealing
Once you're happy, record what was approved and when, including which sample was sealed, which wash standard and which trims. Your gold seal sample is the benchmark that bulk production gets checked against, so the tech pack needs to match it.
Why I build them in Excel
There's loads of tech pack software out there and some of it's great, but I still build mine in Excel.
Most factories can open it and you can update it without paying for a subscription, so it becomes a living document that grows with the style, from first sample right through to production.
A tech pack isn't something you write once and forget about. Every round of fit comments, every trim change and every wash tweak should end up in there, so that by the time you go into bulk, it's the single source of truth for those jeans.
Do you actually need one?
If you're making anything, yes, even if you're only doing a small first run. Especially if you're only doing a small first run, because you won't have the budget for endless rounds of samples.
A good tech pack won't make your first sample perfect, nothing will. But it gets you a lot closer, and when something does go wrong, you can point to the page and say "that's not what we asked for".
If you've got a design and absolutely no idea how to turn it into something a factory can make, get in touch. Building tech packs is a big part of what I do.
Let's fix your fit.