Understanding Weaving Terminology – WPI, EPI, Sett & More (Made Simple for Knitters)

Part 2: Understanding Weaving Terminology – WPI, EPI, Sett & More (Made Simple for Knitters)

If you’re a knitter thinking about trying weaving, you might already be familiar with yarn weights and needle sizes. One glance at a yarn label tells you what you need to know. Weaving, on the other hand… can feel like a whole new language.

Terms like WPI, EPI, Sett, and PPI might seem confusing at first, but once you understand how they relate to the structure of woven fabric, they’ll become a really helpful part of your weaving toolkit.

Let’s break them down—especially with knitters in mind.

A note before we begin…

This is the second post in a 3-part series for knitters who are curious about weaving. Part 1: Can You use Knitting Yarns for Weaving - A Beginner's guide introduced the basics of weaving how it compares to knitting and ways to use your knitting yarns, and Part 2 (this post) now explains essential weaving terms and measurements—like WPI, EPI and sett—to help you confidently assess whether your stash yarns are suitable for weaving. If you're wondering how to use what you already have, this post is your starting point.

WPI – Wraps Per Inch

WPI (Wraps Per Inch) is probably the most familiar to knitters. It’s a way to measure the thickness of your yarn by wrapping it around a ruler or gauge tool to see how many times it fits within an inch.

This is a great place to start when deciding if a yarn will work in a weaving project. You can use a simple ruler or a dedicated EPI counter (available in our Weaving Tool Sets) to measure it. Just wrap your yarn gently side by side—no overlaps or gaps—and count how many wraps fit across one inch.

✨ Tip: If your yarn is plied, be especially careful not to twist it tighter or looser than it naturally wants to sit. Distorting the ply can give you a less accurate WPI reading. Let the yarn sit relaxed and flat for the most reliable result.

Use this number to help determine what kind of fabric your yarn might produce. We’ve even created a handy Yarn Weight Conversion Chart that compares WPI to common knitting yarn categories like DK, Aran, or Laceweight—making it easier to relate to what you already know.

Everyone wraps a little differently, so use WPI as a guide rather than a rule. Keeping a record of your own samples and results will help you build confidence over time.

EPI – Ends Per Inch

EPI tells you how many warp threads (or “ends”) are set up per inch across your loom. Think of it like your cast-on in knitting—it defines the density and structure of your fabric.

There’s a simple starting formula: EPI = WPI ÷ 2

This gives you an estimate for a balanced plain weave—where your warp and weft yarns are the same thickness, and your spacing is just right for those yarns to interlace comfortably.

This setup is known as a Balanced Sett, and it’s made up of four interlocking elements:

• Your warp and weft yarns are the same
• Your reed or sett spacing matches the yarn’s needs (EPI = Sett)
• Your pattern (plain weave)

When these elements align, you reach what I like to call weaving’s sweet spot—a harmonious balance where structure, drape, and appearance come together effortlessly. It's a helpful starting point for understanding how woven cloth behaves.

Sweet Spot for Handwoven Cloth

But here’s the thing: not arriving at that sweet spot is what I call designing.

Once you understand how the balance works, you can intentionally push or pull at any of those elements—changing the warp or weft yarns, adjusting the spacing, altering patterns and even beating harder or lighter—to create something entirely different. This kind of creative exploration is where the real joy of weaving begins.

The sweet spot is a guide, not a rule—and learning how and when to break away from it is part of developing your own weaving voice.

Sett – Finding the Right Spacing for Your Warp

Sett refers to the spacing of your warp threads across the loom—and if you’re coming from a knitting background, think of it like choosing the right needle size for your yarn. The spacing of your warp yarns (your sett) plays a big role in how your finished fabric looks, drapes, and behaves—just like stitch gauge does in knitting.

If your sett is too wide for your yarn, the cloth can become too dense, stiff, or tricky to weave. If it’s too tight, your fabric might turn out loose and unstable. Sett is all about finding the sweet spot where your yarn sits comfortably—creating a fabric that looks and feels just right.

How is Sett Measured?

On a table or floor loom (below left), sett is determined by the size of your reed—a comb-like piece that spaces out your warp yarns. Reeds are labelled by the number of “dents” (slots) per inch, so a 10-dent reed means 10 warp ends per inch, giving you a sett of 10.

On a frame loom, the sett is fixed - it’s built into the loom’s structure through evenly spaced notches or grooves. Most frame looms are set between 2–5, which works well for bulkier yarns and tapestry-style weaving.

Some frame looms - like The Oxford Frame Loom (above right) - are designed with versatility in mind. It features multiple Setts (2, 4, 8 & 16), which allows you to use everything from thick roving to fine yarns—without needing a different loom for each yarn type. It’s a bit like having a full set of interchangeable knitting needles that can handle any yarn in your stash.

✨ Not sure what sett your loom has? Use a ruler or EPI counter and count the number of notches or grooves in one inch. That number = your sett.

Sett vs. EPI – What's the Difference?

Sett and EPI often get used together, but they refer to different things:

• Sett is about your equipment—it's the spacing built into your loom (via the reed or the notches).
• EPI is about your yarn—how many warp threads per inch you choose to use based on the yarn’s thickness.

In an ideal setup—like when you’re weaving with a yarn that fits your loom’s spacing perfectly—Sett and EPI are the same. This gives you a Balanced Sett, and it’s a great place to start when you’re just learning.

But in reality, especially when pulling from your knitting stash, your yarns may not match your loom’s sett—and that’s okay. You might need to double up finer yarns or spread thicker ones out. Sometimes, choosing a yarn that doesn’t quite match your sett can lead to something more textured, open, or unique.

Learning to choose and adapt your yarns with this knowledge is part of the weaving adventure—and intentionally breaking away from perfect balance is what makes it a creative practice, not just a technical one.

Below are some woven samples of what different types of yarn look like at different Setts:

PPI – Picks Per Inch

PPI stands for Picks Per Inch—which simply means how many rows of weft yarn are woven into one inch of fabric. If you’re a knitter, you can think of it like your row gauge in a swatch.

But unlike knitting, most weaving patterns don’t come with a recommended PPI. That’s why sampling is such an essential part of the weaving process—especially when you're working with yarns from your stash.

Before you commit to a larger project, it’s always worth weaving a small sample using your chosen yarns, weave structure, and sett. This sample acts as your reference—showing you how your warp and weft are interacting with the pattern you have chosen and what your real PPI looks like under the current conditions.

Skipping this step might lead to fabric that’s too stiff, too loose, or just not what you expected—and could cost you time, money, and effort. A small sample helps you avoid surprises and gives you the confidence to move forward.

The way you beat (that is, how firmly you pack the weft into place) will also influence your PPI. Some weavers naturally beat harder, creating a tighter, more compressed fabric. Others beat more gently, resulting in a looser, more open weave. Just like knitting tension, there’s no single right way—it’s about finding your style and adjusting accordingly.

✨ Tip: When sampling, count how many picks you’ve woven into one inch of finished cloth. That’s your true PPI—and it will help you plan your project accurately.

What’s Next: From Planning to Designing

Now that you’ve learned how to measure your yarn, set up your warp, and interpret how it behaves during weaving—you’re ready for the next stage: designing.

In Part 3, we’ll look at how to use this knowledge to confidently experiment with your yarn stash. We’ll talk about which yarns are suitable (and which aren’t), how to mix different yarns in creative ways, and how to make intentional choices that turn your cloth into something beautiful—even if it’s not technically “perfect.”

This is where weaving becomes personal—and where your inner designer gets to take the lead.

And if you'd like to try it out in a guided, hands-on environment, you're always welcome to join one of our Weaving Workshops to see how everything comes together!