Crochet
Mosaic crochet: how overlay and inset charts work
Mosaic crochet makes two-color geometric patterns while you only ever work with one color at a time. Overlay and inset mosaic are built differently and their charts read differently, so it pays to know which one a pattern uses.
Updated October 6, 2026
One color per row
Mosaic crochet gives you crisp two-color patterns without ever holding two yarns at once. Each row, or each pair of rows, is worked in a single color. The pattern comes from tall stitches that reach down into an earlier row of the same color and cover the row, or pair of rows, of the other color in between.
The name most likely comes from mosaic knitting, the slip-stitch method Barbara Walker named and first published in A Second Treasury of Knitting Patterns in 1970. Her book Mosaic Knitting came out in 1976. If you knit as well, the mosaic section of Fair Isle vs intarsia covers the knitted version.
There are two main styles, overlay and inset. People mix them up all the time, partly because both use charts with X marks. They're built differently, though, and the charts don't mean the same thing. Check which one your pattern uses before you start.
Overlay mosaic
Overlay mosaic uses two stitches:
- Single crochet in the back loop only. This is the default on every row, and it leaves the front loop of each stitch free for later.
- A double crochet worked into the front loop of the stitch two rows below. Patterns call it a mosaic, long or drop-down double crochet. It lies in front of the row in between and covers it.
Every time you work one of those double crochets, skip the stitch directly behind it in the current row. If you don't, you add a stitch and the row creeps wider.
Colors alternate every row: A, B, A, B. So the stitch two rows below is always the same color you're holding, and a dropped double crochet looks like that color continuing upward over the stripe in between.
You always work with the right side facing you, and you never turn. At the end of each row you fasten off, then join the next color back at the start. That leaves two tails per row, one at each end.
The front has a raised, textured look where the double crochets sit on top. The back is just stripes.
Inset mosaic
Inset mosaic uses single crochet, chains and double crochet, and each color is worked for a pair of rows: one on the right side, then you turn and work one on the wrong side.
On those rows, wherever the other color should show, you chain 1 and skip the stitch instead of working it. That leaves a little gap. On a later row in the other color, a double crochet goes down in front of the chain spaces and into the skipped stitch three rows below, filling the gap with its color.
Because each color works across and back, it finishes at the same edge it started from. You carry the yarn not in use up the side and pick it up when its turn comes, so there's no fastening off every row and far fewer ends. The fabric comes out smoother and lighter in weight than overlay.
Overlay and inset side by side
| Overlay | Inset | |
|---|---|---|
| Rows per color | 1, then switch | 2, a right side row and a wrong side row |
| Turning | Never, the right side always faces you | At the end of every row |
| Stitches | Back loop sc, dc into the front loop 2 rows below | sc, ch 1 spaces, dc into a skipped stitch 3 rows below |
| Ends | Two per row | Few, the yarn is carried up the side |
| Look | Raised texture, striped back | Smoother and lighter in weight |
| One chart row means | One row | A pair of rows |
Reading an overlay chart
Overlay charts are read from the bottom up. If you crochet right-handed, every row goes from right to left, since you never turn. If you crochet left-handed, every row goes from left to right.
Each row shows its color at the edge of the chart, often as a column of colored squares down one side. That's the yarn you hold for the whole row. Then:
- A plain square is a single crochet in the back loop.
- A square with an X is a double crochet in the front loop of the stitch two rows below, skipping the stitch behind it.
The colors in the body of the chart show what the finished fabric will look like. They don't tell you which yarn to use for that square. You'll see squares of color A sitting in a color B row, because a dropped double crochet covers that spot. Ignore them. Work the whole row in its color and follow the X marks.
Most patterns begin with a row or two of plain single crochet before the first X, because a double crochet needs a row two below to drop into. Many patterns also start and end every row with an edge stitch, often a single crochet through both loops, which makes a neater, sturdier edge. Your pattern will say how it handles edges.
A ruler or sticky note under the current row helps more than usual with mosaic charts. Rows of X marks look very alike, and it's easy to read the row above by mistake.
Reading an inset chart
On an inset chart, each row of squares stands for a pair of rows in the same color. If you crochet right-handed, read it from right to left for the right side row, then turn and read the same chart row from left to right for the wrong side row.
- A square in the color you're working: single crochet.
- A square in the other color: chain 1 and skip a stitch.
- A square with an X: on the right side row, a double crochet worked in front into the skipped stitch of the same color three rows below.
On the wrong side row, work a single crochet in each single crochet and double crochet, and chain 1 over each chain 1.
Symbols and edge stitches vary between designers, so read the key and the pattern notes before you start.
Common mistakes
- Dropping the overlay double crochet into the row directly below. The stitch two rows below is always the color you're holding. If you're reaching into the other color, you need to go one row lower.
- Forgetting to skip the stitch behind a dropped double crochet. The row gains a stitch and the pattern drifts. Count stitches at the end of every row until it's automatic.
- Working the overlay single crochets through both loops out of habit. That uses up the front loop a double crochet will need two rows later.
- On inset rows, working a single crochet where the chart shows the other color. That square needed a chain 1 and a skipped stitch, and without the gap there's nowhere for the double crochet to go.
Leaving tails at row ends
Overlay worked flat in rows leaves a tail at both ends of every row. A blanket 150 rows long has 300 of them. Weaving each one in is possible, and some people do it on small pieces, but most overlay patterns plan for the tails from the start. The common choices:
- Leave the tails hanging and trim them to one length as a fringe. For a twisted fringe, twist two neighboring tails, tie them together and let them twist around each other.
- Hide them in an envelope border. You work one border on the back of the piece and one on the front, then join the two, and the tails end up sandwiched inside.
- Sew them in with a yarn needle, which is easiest on small pieces like coasters.
Leave the tails long while you work, whichever finish you plan. A long tail can be trimmed later, but a short one is hard to sew in or knot.
Inset mosaic mostly avoids the issue, since the colors run up the side.
Planning your own mosaic design
Two colors with strong contrast show mosaic best, because the whole pattern is one color laid over the other. Smooth, light-colored yarn also makes the front loops easier to see while you learn.
A mosaic chart isn't a free drawing. Every square has to be something the stitches can make, and a pixel-style picture drawn without the rules in mind usually isn't workable. Swatch one repeat of any design before you commit to a blanket.
Craft Studio's crochet colorwork editor (free, with an account) lists overlay mosaic as a project type, though it won't check the mosaic rules for you. The free knitting graph paper tool prints grids sized to your swatch if you'd rather sketch by hand, and it works for crochet. If you want pictures with any number of colors in a row, tapestry crochet carries them inside the stitches instead.
Frequently asked
- What is the difference between overlay and inset mosaic crochet?
- Overlay mosaic changes color every row, is always worked from the right side, and makes its pattern with double crochets worked into the front loops two rows below. Inset mosaic works each color for two rows, turning in between, and fills chain-1 gaps with double crochets into skipped stitches three rows below. Inset leaves far fewer ends.
- What does an X mean on a mosaic crochet chart?
- On an overlay chart, an X means a double crochet in the front loop of the stitch two rows below, skipping the stitch behind it. On an inset chart it means a double crochet, worked on the right side row in front into the skipped stitch of the same color three rows below. Check which style your pattern is before you start.
- Do you cut the yarn every row in mosaic crochet?
- In overlay mosaic worked in rows, yes. You fasten off at the end of every row and join the next color at the start, so each row leaves two tails. Inset mosaic carries the yarn up the side, so you rarely cut it.
- How do you hide the ends in overlay mosaic crochet?
- Most patterns either turn the tails into a fringe or hide them in an envelope border, which is two borders worked on the front and back and joined with the tails inside. On small pieces you can sew the ends in with a yarn needle.
- Why are some squares on a mosaic chart a different color from the row?
- The chart shows what the finished fabric will look like, not which yarn to use for each square. You always work the whole row in the color shown at the edge. The X marks tell you where to drop stitches down, and the design builds up as you go.