Precut friendly quilt patterns are the holy grail of quilt pattern writing, and no precut is more popular than fat quarters. While you might not love the variety that fat quarters add to a quilt yourself, it is undeniable that lots of quilters do, and making your quilt pattern able to accommodate them (even if it's only one option of several) can make your pattern MUCH more popular.
But . . . the math and cutting instructions for fat quarter-friendly patterns can get tricky, to say the least! Then there's the whole issue of how to organize the pattern so it makes sense to your customer and is easy to follow. Fat quarter-friendly patterns can easily send you down a rabbit hole that it takes weeks to emerge from.
I've written a few of these things (fun fact, it's exactly the type of pattern my clients love to hand off to a ghostwriter), so I'm sharing some tips I've learned to make writing fat quarter-friendly patterns a little easier.
Strategies for dealing with the quilt math
There's lots of different ways to work out the quilt math for a fat quarter-friendly pattern. However, there are a couple of ways that make your life much easier later on as you try to organize the pattern. These are my favorite ways that make the later organization a cinch.
For all of these methods, use a graphics program (like Adobe Illustrator or Inkscape) or graph paper to virtually cut your fabric at actual scale. This is the easiest way I know to make sure beyond the shadow of a doubt that all the necessary pieces will fit on a fat quarter.
1. X blocks per fat quarter
With this strategy, each fat quarter is used to make as many blocks as possible. If your blocks are big, each fat quarter might be used for only one block. If your blocks are smaller, you might be able to achieve 2, 3, or even 4 blocks per fat quarter.
Suzy Quilts' "Voyage" quilt pattern is a great example of an
X blocks per fat quarter quilt pattern
Figure out how many blocks you can fit on a fat quarter, then divide the number of blocks needed for each size by the number of blocks per fat quarter to get the number of fat quarters required. If you're in doubt how many blocks you should put per fat quarter, always air on the side of more scrap than less. Fat quarter dimensions can vary quite a bit from manufacturer to manufacturer and shop to shop. You always want to have at least 1/2" around 2 sides of the fat quarter (never exact), with 1" ideal. Never assume a fat quarter is larger than 18" x 21".
This method greatly simplifies the cutting instructions since each fat quarter is cut exactly the same way. What changes between sizes is simply the number of fat quarters that need to be cut. Each block will feature a different fabric.
You can repeat this process for each type of fabric used within the block or use strategy #2 if the contrasting fabrics are not background cut from yardage. The drawback to this method is that block fabrics may be repeated more than once. If you're looking to maximize your variety, another strategy may be more appropriate.
You will want to include a section outlining how to cut each set of fat quarters and listing how many fat quarters need to be included in each set for the various sizes.
2. Exchanging fabric types
With this strategy, each fat quarter may only be used to cut 1-2 blocks, but each fabric will be used at each position within the block at least once, yielding lots of variety. Determine all cuts of fabric needed for a block (as if you were cutting all the pieces from one fabric. Then, figure out if more than one block's worth of pieces will fit on a fat quarter. Typically, only one block will fit, unless you're using yardage for background. Divide the number of blocks needed by the number of blocks per fat quarter to get your fabric requirements.
Suzy Quilts' "Shining Stars" pattern is a great example of an
exchanging fabric types fat quarter pattern
This method is great for quilts with no background fabric or for a controlled scrappy look. It makes the cutting instructions easy because all fat quarters are still cut the exact same way. However, you will want to include a "sort your fabrics" section in your pattern, usually after the cutting section, which instructs your reader to mix and match their fabrics to create block sets.
From there, the rest of the pattern organization is pretty straightforward. Take your reader through the process of making one complete block, and then instruct them to repeat it with each remaining block set.
3. Strip piecing with fat quarters
Strip piecing in a fat quarter-friendly quilt is tricky, but doable. You'll still want to apply either of the first two strategies where you are either cutting multiple blocks from a single fat quarter, or cutting all pieces from a fat quarter and then exchanging fabrics (harder).
Once you figure out how many strip units you need to cut from a single fat quarter to fulfill the block requirements, you can calculate the minimum length of strip set needed to produce the strip units you need. If that length is closer to 18" than 21", you want to cut these strips length of fat quarter (LOFQ) rather than width of fat quarter (WOFQ). More on this later. ALWAYS make sure you have at minimum 1/2" extra length for trimming, 1" is preferable.
If you will still produce a lot of waste from the strip set cutting either LOFQ or WOFQ, you can consider pre-cutting smaller lengths, but I would avoid this if possible. One of the advantages of strip piecing is that you don't have to do any pre-cutting beyond strips in order to be ready to sew, and long rectangles (greater than 12" in length) can be difficult to cut with most standard rulers.
If you are pairing background strips with your fat quarter strips, instruct your reader to cut regular WOF strips and then cut them approximately in half. Those will pair perfectly with a WOFQ strip. You can do the same thing if you're using LOFQ strips, just understand that you'll have approximately 3" of overhang for each FQ strip. Many people are OK with this given the cutting simplification it provides.
Width of Fabric (WOF) , and therefore width of fat quarter (WOFQ), is always the direction perpendicular to the selvage edge. This will ALWAYS be 21" in fat quarters due to the way they're cut. Please don't get this confused with the width of a cut of fabric for which it is customary to use the shorter dimension. Length of fabric (LOF), and therefore length of fat quarter (LOFQ) is always parallel to the selvage edge and thus will ALWAY be the 18" dimension on a fat quarter. If you end up using these abbreviations in your pattern, include their definitions in a "before you begin" or "definitions" section.
Organization is key with precut-friendly quilt patterns since often multiple fabrics are being used in the same positions. Here are some best practices:
1. Write the cutting instructions on a per-fat quarter basis. This makes it easy for your reader to work through each fat quarter knowing exactly what they should cut. If you have multiple sizes that require a different number of fat quarters to be cut, you can include the number of fat quarters for each size as additional columns. Here's what that might look like:
If you have multiple sets of fat quarters that must be cut, include those as additional cutting sections, NOT in the same section. That only leads to more confusion.
2. If each fat quarter's pieces are meant to stay together within a block, instruct the reader to keep each FQ's pieces together as a set throughout the rest of the pattern in the cutting instructions. Sometimes designers will put this instruction later, but by that time, quilters may have already mixed up their pieces.
3. Include a cutting diagram showing how each set of fat quarters gets sliced and diced. This is not strictly necessary if all of your pieces are simply subcut from WOFQ or LOFQ strips, but it is often still helpful for visual folks, especially if there is not much extra fabric to go around. It is required if you are not simply subcutting strips like in the diagram below.
In that diagram, it is important to indicate which edge is the 18" side and which edge is the 21" side, especially if things are not entirely to scale. Fat quarters are nearly square so it can be easy to get the two directions confused.
4. Label the pieces cut from a fat quarter, both in the cutting table and in the diagram. If the pieces are large, you may also include dimensions on the diagram as well, but often, I have found that the diagrams become far too cluttered when trying to do that. It's more important for the diagrams to be clearly legible than it is to include dimensions on the diagram.
Labeling the pieces uniformly makes it easy to refer to them in the actual construction instructions without having to address the fact that each block has a different fabric for the same piece.
5. Write your instructions on a per block basis, i.e. go through all the instructions for constructing a single block (no chain piecing, no making all your HSTs first). That way, making additional blocks is simply a matter of repeating the instructions regardless of the fabrics used. This makes it easy to keep of which pieces are meant to be matching within blocks and which are not, if you're exchanging fabrics. Otherwise, it can be difficult to articulate that you need 4 matching HSTs of one fabric, and 8 matching HSTs of another, etc. within each block.
This especially important if you're sorting your fabrics into block sets beforehand. You'll gather your set of pieces required at the beginning, and then move through the remainder of the instructions without having to worry if all the right pieces are matching.
6. Color code your diagrams so that each color corresponds to a fabric that is supposed to match within a block. Block to block, these colors will change, but within a block, they're supposed to match and your diagrams should reflect that.
Things to avoid
The #1 mistake I see from designers when it comes to fat quarter-friendly patterns is not providing some sort of pattern/consistency to how the fabrics are distributed. (Like exchanging fabrics, or X blocks per fat quarter.) Without some logic, you end up with almost every fat quarter cut differently (believe me, I've seen it) and it makes it almost impossible for your reader to wrap their head around the design in a way that makes it easy to plan their own fabrics (let alone really difficult to write!).
This pitfall is not exclusive to fat quarter patterns; I've seen it with ombre deigns and patterns with 6 or more feature fabrics also, but it's especially important for fat quarter-friendly patterns.
Without some method to the fabric/color madness, it's very easy for a fat quarter pattern to begin to look like a scrappy pattern which isn't ideal either. If you want to write a scrappy pattern, write a scrappy pattern (i.e. one that just lists approximate fabric requirements or total piece numbers). There's no need to start with a relatively large piece of fabric if ultimately you're just cutting everything down into 2-5" pieces and randomizing everything.
There are many other strategies for organizing your fat quarter friendly; this is by no means an exhaustive list. But whatever strategy you choose, make sure it's organized. That's the magic in the madness.