DU 402: The Art of Pattern Making
Summary
Before a single piece of fabric is cut, someone has to draw the blueprint — and that drawing is called a pattern. There are three ways in: deconstruct an existing pair and trace it (the best starting point for beginners), use commercial patterns (useful for learning construction but rarely a finished solution), or draft from scratch using a mathematical algorithm. The straight side seam is non-negotiable for selvedge denim. The crotch line is your anchor — it does not move. And the most important advice in this article: start before you feel ready. The pattern will teach you things no article can.
Q&A
What is a sloper and why is it valuable?
A sloper is a base pattern with no design ease built in — just the essential geometry of a fit, stripped of seam allowances. It's created by deconstructing a well-fitting pair of jeans, tracing every piece, and removing the seam allowances. A sloper is one of the most valuable things a maker can have: it becomes the foundation for every other pattern you'll ever develop. Adjust the rise here, widen the leg there, and you have a new fit without starting from scratch every time.
Why is a straight side seam essential for selvedge denim patterns?
Selvedge fabric is approximately 30 inches wide — half the width of wide-goods denim — and waste is expensive. When the side seam is straight (truly vertical), the front and back pattern pieces can be nested tightly against each other on the fabric with almost no wasted cloth between them. Any curve in the side seam introduces wasted space that can't be filled with another pattern piece. On a 30-inch bolt, that waste adds up fast. There's also an aesthetic reason: a straight seam keeps the selvedge ID running cleanly along the outseam.
Why does the crotch line not move during pattern adjustments?
The crotch line is the anchor of the entire pattern — the reference point against which every other measurement is calibrated. If the rise is too long, shorten the pattern at the waistband. If the leg is too short, add length at the hem. The crotch line stays fixed because it is also the structural meeting point of the inseam and the top block. Move it, and you lose your reference. Keep it fixed, and you're always working from solid ground.
What does "the pattern is trying to tell you" mean in practice?
Pattern making involves a set of recurring technical signals that indicate something isn't working. Where two pieces meet and continue as a line, they should meet at right angles — otherwise you get a bump or hollow in the finished seam. The front piece should lean slightly forward while the back stays more vertical, reflecting the forward tilt of the human body. The center back seam needs curve to prevent waistband gapping. Front pockets should be cut slightly larger than the body to prevent pulling. These are the things the pattern shows you when you cut, sew, and wear — which is why starting is the only way to learn them.
What is the honest difference between the science and art of pattern making?
The algorithm gives you a starting point — put in accurate measurements, follow the geometry, and you'll produce something that fits reasonably well. That's the science. The ceiling is somewhere else. Getting a pattern to a place where it fits the way a great pair of jeans should fit takes something the algorithm can't give you: sustained effort, the willingness to cut a pair and wear it and pay attention, the humility to throw out a pattern that isn't good enough. Effort is necessary but not sufficient. What separates a pattern that works from one that's genuinely great is iteration — and iteration requires starting.
Test Your Knowledge
Click each answer to reveal whether it's correct.
1. What is the recommended starting point for a beginner who wants to make their own jean pattern?
A. Draft from scratch using a mathematical algorithm
❌ Incorrect. Drafting from scratch is the most involved path and gives the deepest understanding — but it's not the recommended starting point. Deconstructing an existing pair gives you a working pattern and a sloper simultaneously, with the educational bonus of seeing how the pieces actually relate.
B. Deconstruct a well-fitting pair of jeans, press each piece flat, and trace onto pattern paper
✓ Correct. Deconstructing a pair you love gives you two things at once: a working pattern you know produces a fit you like, and — once you strip the seam allowances — a sloper. The educational value is also high: deconstructing a well-made pair is like taking apart a watch to see how it works. You see how pieces relate, where ease is built in, how curves are actually drawn.
C. Buy a commercial pattern from one of the Big 4
❌ Incorrect. Commercial patterns are a reasonable introduction to construction sequence and pattern anatomy, but they're engineered for a statistical average across a size range. Almost everyone who works seriously with commercial patterns spends as much time adjusting them as they would have drafting something closer to purpose-built.
D. Take a formal patternmaking course before cutting any fabric
❌ Incorrect. Formal courses have real value, but the article's advice is clear: start before you feel ready. The pattern will teach you things that no course or article can. Waiting until you're formally prepared is the surest way to delay learning.
2. Why must selvedge jean patterns have a straight side seam?
A. Curved side seams weaken the selvedge edge and cause fraying
❌ Incorrect. Curved side seams don't weaken the selvedge edge. The reason for a straight side seam is about fabric efficiency — allowing pattern pieces to nest tightly on a narrow 30-inch bolt with minimal waste.
B. Selvedge fabric is only 30 inches wide — a straight side seam allows pieces to nest tightly with minimal wasted cloth between them
✓ Correct. Any curve in the side seam introduces wasted space that can't be filled with another pattern piece. On a 30-inch bolt — half the width of wide-goods fabric — that waste adds up fast. A straight side seam also keeps the selvedge ID running cleanly along the outseam, which matters for the train track fade.
C. Curved side seams distort the twill line of the denim
❌ Incorrect. A curved side seam wouldn't inherently distort the twill line any more than a straight one. The reason for a straight side seam is fabric efficiency on a narrow bolt, not twill preservation.
D. Shuttle looms can only produce fabric with straight edges, requiring straight seams
❌ Incorrect. Shuttle looms produce the selvedge edge, which runs straight — but the pattern pieces can be cut at any angle from the bolt. The straight side seam requirement is about yield, not loom construction.
3. What is the most important rule in pattern drafting?
A. Always add 1 inch of ease to every measurement
❌ Incorrect. Ease amounts vary by measurement and fit preference — there's no universal 1-inch rule. The most important rule in pattern drafting is about a specific structural anchor point.
B. The crotch line is your anchor — it does not move
✓ Correct. The crotch line is the reference point against which every other measurement is calibrated. If the rise is too long, shorten at the waistband. If the leg is too short, add at the hem. Move the crotch line and you lose your reference. Keep it fixed and every other adjustment works from solid ground.
C. The side seam must always be longer than the inseam
❌ Incorrect. Side seam vs. inseam length is a proportional matter that varies by rise and leg length — not a universal rule. The most important rule is about the crotch line as an immovable anchor.
D. Cut patterns on the bias for maximum stretch
❌ Incorrect. Denim jeans are cut on the grain, not the bias. Bias cutting is a technique for specific garment types that require drape. The most important rule in jean pattern drafting is keeping the crotch line fixed.
4. Why should front pockets be cut slightly larger than the body measurement?
A. Larger pockets accommodate more items and are more functional
❌ Incorrect. The reason isn't about storage capacity — it's about how the pocket bag curves around the hip and leg inside the jean when worn. Without ease, the pocket pulls tight and is uncomfortable.
B. The pocket bag curves around the hip inside the jean — without ease it pulls tight when worn; the slight puff of the finished pocket indicates room inside
✓ Correct. When a pocket is sewn in, the pocket bag curves around the hip and leg inside the jean. If cut to match the body exactly, it pulls tight when the jean is on — hard to get a hand in, uncomfortable when sitting. The solution is cutting the pocket U slightly larger. When sewn correctly, the pocket stands slightly proud of the jean face — a small puff that looks like a flaw but is actually the sign of a well-made pocket.
C. Extra fabric is needed to accommodate shrinkage after the first wash
❌ Incorrect. Shrinkage is accounted for at the pattern level, not specifically at the pocket. The reason for cutting pockets larger is to build in the ease the pocket needs to curve around the hip without pulling tight.
D. Larger pockets are easier to sew at the machine
❌ Incorrect. Ease of sewing is not the reason. The pocket needs to be cut larger to accommodate the three-dimensional curve it takes when worn against the body.
← Previous: DU 401 | ↑ Denim University | Next: DU 403 →
By Eric Steffen
Founder / Maker
FITTED Underground
The Blueprint
Every pair of jeans that has ever existed started as a pattern. Before a single piece of fabric was cut, before a single seam was sewn, someone sat down with paper and pencil and worked out the geometry of how flat cloth becomes something that fits a three-dimensional human body. That drawing — those curves and lines and notches — is the pattern. And everything that happens downstream, every fitting decision and construction choice, flows directly from it.
I started making patterns in 2013, the year before I left finance to start FITTED Underground. I have revised, redrawn, and refined those patterns hundreds of times since. I am still learning from them.
The best advice I can give anyone who wants to make their own jeans: start before you feel ready. The pattern will teach you things that no article can.
This article is for anyone who wants to understand how patterns work — and for anyone who wants to make their own. If you're in the second group: the best advice I can give you is to start before you feel ready. The pattern will teach you things that no article can.
Three Ways In
There is no single correct path to a working jean pattern. There are three, and each one is legitimate. The right choice depends on where you are in your journey.
Option 1: Deconstruct and Draft
This is where I'd tell almost any beginner to start, and it's exactly what it sounds like. Find a pair of jeans — vintage shop, your own closet, wherever — that closely mirrors the fit you want to achieve. Take it apart at the seams. Press each piece completely flat with an iron. Then trace every piece onto card stock or pattern paper, marking as you go where the seam allowances fall.
What you end up with is two things at once. First, a working pattern — one that you know produces a fit you like, because you're looking at the physical evidence of it. Second, if you strip the seam allowances out of those pieces, you have a sloper: a clean, neutral base pattern with no design ease built in, just the essential geometry of the fit. A sloper is one of the most valuable things a maker can have. It becomes the foundation for every other pattern you'll ever develop — adjust the rise here, widen the leg there, and you have a new fit without starting from scratch every time.
The underrated advantage of this method is educational. Deconstructing a well-made pair of jeans is like taking apart a watch to see how it works. You'll see how the pieces relate to each other, where ease has been built in, how the curves at the crotch and hip are actually drawn. No algorithm teaches that as viscerally as holding the pieces in your hands.
Option 2: Commercial Patterns
The major commercial pattern companies — Vogue, McCall's, Butterick, and Simplicity, collectively known in the sewing world as the Big 4 — all produce pants and jeans patterns that are widely available and relatively affordable. Butterick, the oldest of the four, has been producing standardized paper patterns since 1863, when Ebenezer Butterick invented the graded multi-size pattern and made home garment-making accessible to people without formal training.
Commercial patterns are a reasonable starting point if you want a guided introduction to construction sequence and pattern anatomy before you start making your own decisions. The honest caveat: they are engineered to fit a statistical average across a size range, not any specific body. Almost everyone who has worked seriously with commercial patterns has spent as much time adjusting them as they would have spent drafting something closer to purpose-built from the start. They're a useful learning tool. They're rarely a finished solution.
Option 3: Draft from Scratch
The most involved path, and the one that gives you the deepest understanding of what a pattern actually is. Drafting from scratch means starting with a full set of body measurements — waist, hip, thigh, inseam, rise, and more — and using a mathematical algorithm to translate those measurements into the curves and proportions of a pattern.
It's the method I used when I first started in 2013. I'm not going to walk through the full algorithm in this article — that goes beyond what words alone can teach and is better learned by doing. But I will cover the key decisions and common pitfalls in the sections below. If you're serious about drafting your own pattern, find the algorithm, take your measurements carefully, and start cutting. The rest comes from repetition.
The Selvedge Pattern: Different Rules
Before getting into drafting specifics, it's worth pausing on a constraint that's specific to selvedge denim — because it changes how the pattern has to be drawn.
Selvedge fabric is approximately 30 inches wide. Wide-goods denim is approximately 60 inches wide. That difference in width isn't just a number — it means that for every meter of selvedge you cut, you have half the usable fabric you'd have with wide goods. And selvedge takes significantly longer to mill on a shuttle loom, which means it costs more per meter to begin with. Waste is expensive. Maximizing yield isn't optional — it's fundamental to making selvedge denim economically viable at the maker scale.
The primary tool for maximizing yield is a straight side seam. When the side seam of a jean pattern is straight — truly vertical, no curve — the front and back pattern pieces can be nested tightly against each other on the fabric, with almost no wasted cloth between them. Any curve in the side seam introduces wasted space that can't be filled with another pattern piece. On a 30-inch bolt, that waste adds up fast.
The straight side seam constraint becomes significant at larger sizes. Above a size 38 waist, drafting a well-proportioned selvedge pattern becomes genuinely difficult, and sometimes impossible depending on the fabric width. It's one of the reasons you don't often see selvedge jeans in larger sizes — not because makers don't want to produce them, but because the geometry of the fabric makes it hard.
The Two Lines: Setting Up Your Pattern
When you sit down to draft a jean pattern — whether from an algorithm, from a deconstruction, or from intuition built up over years — you begin with two lines.
The first is a vertical line running top to bottom along the paper. This is the side seam. Everything else orients to it.
The second is a horizontal line crossing the paper at the crotch point. This line divides the pattern into two zones: the top block (everything from the crotch up to the waistband) and the leg taper (everything from the crotch down to the hem). If you've read DU 202, this mental model will be familiar — a pair of jeans is really two problems stacked on top of each other, and the crotch line is where they meet.
Here is the most important rule in pattern drafting: the crotch line is your anchor. It does not move.
When something about the fit isn't working, the instinct is often to redraw the crotch. Resist it. If the rise is too long, shorten the pattern at the waistband. If the leg is too short, add length at the hem. If the thigh feels too tight, address it in the thigh. The crotch line stays exactly where it is, because it is the reference point against which every other measurement is calibrated. Move it, and you lose your reference. Keep it fixed, and you're always working from solid ground.
What the Pattern Is Trying to Tell You
This is where pattern drafting stops being geometry and starts being craft. The algorithm gives you a starting point. What follows is a process of listening — to the pattern, to the fabric, to the body you're fitting — and making adjustments until the thing sings.
Where two pieces meet and continue as a line, they should meet at right angles. At the crotch point on the inseam, and at the hip on the side seam, the transition from one pattern piece to the next should be smooth. If the pieces meet at an angle, you'll get a bump or a hollow in the finished seam.
The front piece leans forward; the back piece stays more vertical. The human body isn't symmetrical front to back. A well-drafted pattern reflects this. The front piece should angle slightly toward the hip as it rises toward the waistband, while the back piece remains closer to vertical. This is what keeps the side seam running straight down the leg rather than twisting.
The center back seam needs curve. The fix for gapping at the center back waistband is built into the pattern. The center back seam should be cut at a slight angle or curve so the waistband presses gently against the body. Get the angle right and the waistband sits cleanly. Get it too aggressive and you'll see puckering just below.
Build ease into the front pockets. When a pocket is sewn in, the pocket bag curves around the hip and leg inside the jean. If the pocket opening is cut to match the body exactly, the pocket will pull tight when the jean is on. Cut the pocket U slightly larger than you think you need. When sewn in correctly, the pocket should stand slightly proud of the jean face — a small puff of fabric indicating there's room inside. It looks like a flaw. It's actually the sign of a well-made pocket.
The Art Part
The title of this article is not a metaphor.
Pattern making is based in science. The algorithm is a mathematical system. Put in accurate measurements, follow the geometry, and you'll produce something that fits reasonably well. That's the science. That's the floor.
The ceiling is somewhere else entirely.
Getting a pattern to a place where it fits the way a great pair of jeans should fit — where the rise sits exactly right, the thigh has room without being baggy, the seat follows the body without pulling, the leg hangs straight from hip to hem — that takes something the algorithm can't give you. It takes time. It takes the willingness to cut a pair, wear it for a few weeks, and pay attention to what you feel. It takes the humility to throw out a pattern you worked hard on because it isn't good enough.
Effort is necessary but not sufficient. What separates a pattern that works from one that's genuinely great is sustained effort — iteration after iteration, until the thing finally does what you want it to do.
I have been making patterns since 2013. I am still refining them.
The best advice I can give someone who wants to make great jeans: start now. Start with a pair you love. Take it apart. Trace it. Cut it in a cheap fabric. Put it on. Write down what's wrong. Fix it. Cut it again.
The pattern will teach you everything. But only if you start.
What Comes Next
DU 402 covers the blueprint. DU 403 covers what you do with it — walking through the full process of constructing a pair of jeans from cut fabric to finished garment. That's DU 403: How to Make a Pair of Jeans.
← Previous: DU 401 — How Denim Is Made | Next: DU 403 — How to Make a Pair of Jeans →
Core Curriculum
Complete the core curriculum by reading these essential classes.
- DU 101 — What is Raw Denim?
- DU 102 — What is Selvedge Denim?
- DU 104 — Denim Weight Explained
- DU 201 — How to Buy Your First Pair of Raw Denim Jeans
- DU 204 — How Much to Spend on Raw Denim
- How It Works — FITTED Underground
Eric Steffen is the founder of FITTED Underground, a custom jeans and raw denim workshop at 108 Bayard Street in Williamsburg, Brooklyn. He has been making jeans by hand since 2014. Denim University is his attempt to share everything he's learned — about the history, the craft, and the culture behind the world's most enduring garment.
