C2C Crochet Chart & Tile Guide
A C2C chart is a grid, and every square on it stands for one block of crochet. That makes the chart a counting device: it tells you how many blocks and what colour, never how big. Finished size comes from measuring a block and multiplying — and because a worked block is rarely square, the width and the height have to be measured and multiplied separately.
Chart columns × measured block width = finished width. Chart rows × measured block height = finished height. Two sums, because a block has two dimensions and they are seldom equal.
What Is a C2C Crochet Chart?
Corner-to-corner crochet builds fabric out of small square-ish blocks worked along diagonals, starting at one corner and finishing at the opposite one. A C2C chart is the map of that fabric: a grid where each cell carries a colour, and the arrangement of colours is the picture the finished piece will show. Charts of this kind are often called graphs, and a blanket worked from one is often called a graphghan.
The chart is deliberately abstract. It records structure and colour, and it leaves size entirely to you, because the same chart worked in aran weight and in 4-ply produces two very different blankets.
What Does One C2C Chart Square Represent?
One block. In standard C2C that block is three stitches worked into a chain space, and on the chart it occupies exactly one cell regardless of how large it turns out in yarn.
This is the distinction the rest of the page rests on. A cell is a count. A block is a measurement. Charts are square-ruled for the same reason graph paper is, not because the fabric will be.
C2C Blocks, Tiles and Clusters: Are They the Same?
Broadly yes, and the variation is vocabulary rather than construction. Block is the most common term in written patterns. Tile tends to appear when the discussion is about sizing and layout, as it is here. Cluster describes the same three-stitches-and-a-chain-space unit from the point of view of stitch anatomy. Cell and pixel belong to the chart rather than the fabric.
Where a pattern uses these terms differently it will say so. Nothing here depends on which word you prefer, only on being consistent about whether you are counting chart cells or measuring worked blocks.
How to Read a C2C Chart
Charts are read along diagonals rather than straight across, which is the part that trips people up first. Working from the starting corner, each pass crosses the chart at forty-five degrees to the grid; the cells that pass touches are the blocks worked on that pass, in order.
- Find the starting corner. Most charts mark it. If yours does not, the corner you begin from determines which way the image will face.
- Read one diagonal at a time. The first pass is one cell, the second two, and so on.
- Alternate direction. Successive diagonals are worked in opposite directions, so every other one is read back the other way.
- Take colour from the cell. Each cell's colour is the yarn that block is worked in.
How C2C Diagonals Grow
While the piece is still widening, each diagonal holds one more block than the one before it. The running totals are therefore 1, 3, 6, 10 and so on — the triangular numbers, n × (n + 1) ÷ 2 after n diagonals.
It is worth being precise about the limit of that rule: it describes the increasing phase only. Once the piece reaches its full width the totals stop following it, which is what the next section is about.
Increasing, Maintaining and Decreasing
A C2C piece passes through up to three phases. It widens until it reaches the shorter side of the grid, holds that width while the longer side is crossed, then narrows to the far corner.
The counting works out exactly. A grid of 12 columns and 7 rows is worked in 12 + 7 − 1 = 18 diagonals: 7 widening, 5 holding at the full 7 blocks, and 6 narrowing. Those diagonals contain 12 × 7 = 84 blocks between them, which is simply the size of the grid — the diagonals change the order the blocks are worked in, never how many there are.
A square grid has no holding phase. There is no longer side to cross, so it widens to the middle and narrows away again.
How to Measure a C2C Tile
Work a small swatch in the yarn, hook and tension you intend to use, several blocks across and several down. Then measure the whole swatch and divide, rather than measuring one block.
average block width = swatch width ÷ blocks across
average block height = swatch height ÷ blocks down
The reason is error, and it is worth stating exactly. Suppose your tape reading is out by some amount. Measure a single block and that full error is carried into every block of the project. Measure across 8 blocks and divide, and the error is divided by 8 too — the projection over a whole blanket is out by a factor of 8 less. The improvement is exactly the number of blocks you measured across.
How to Estimate Finished C2C Size
Two multiplications, kept apart:
estimated width = columns × block width
estimated height = rows × block height
| Input | What it measures | What it determines |
|---|---|---|
| Chart columns | Blocks across the grid | Finished width, with block width |
| Chart rows | Blocks down the grid | Finished height, with block height |
| Block width | One block across, from a swatch | The horizontal scale of the whole chart |
| Block height | One block down, from a swatch | The vertical scale of the whole chart |
| Columns × rows | Total blocks | How much work and how much yarn |
| Columns + rows − 1 | Total diagonals | How many passes to the far corner |
These are estimates, and honestly so. Blocking will move them, yarn relaxes differently by fibre, and tension drifts over a project the size of a blanket. What the arithmetic gives you is a sound expectation rather than a guarantee.
How Many Tiles Do You Need?
Run the same relationship backwards. Divide the size you want by the block size you measured:
columns = target width ÷ block width
rows = target height ÷ block height
Round each to a whole number, because you cannot work part of a block, and then multiply back to see what that rounding actually gives you. That last step is the one people skip.
Square vs Rectangular C2C Projects
A square grid does not produce a square blanket unless your blocks are square, and usually they are not. Worked at the block size measured for this page, a 50 × 50 chart finishes about 107.5 cm by 95 cm — 12.5 cm wider than it is tall, from a perfectly square chart.
If you want a square result, choose the grid to suit the blocks rather than assuming the grid shape carries through. Divide your target width by block width and your target height by block height, and accept two different counts.
Reading Color Changes in a C2C Graph
Each cell's colour is the yarn its block is worked in, so a colour change on the chart is a colour change at that block. Because diagonals cross the grid at an angle, a change that looks like a clean vertical line on the chart arrives as a staircase of changes spread over many separate diagonals.
Practical consequences worth planning for: count the colour changes per diagonal before you start a complex row, because a diagonal crossing a detailed area may carry several; and expect isolated single blocks of a contrast colour to need their own yarn management, since carrying a colour a long way behind the work shows through and distorts the fabric. For the wider techniques, crochet colourwork techniques covers the joining and carrying methods themselves.
Worked C2C Sizing Examples
The swatch these examples use. 8 blocks measured 17.2 cm across and 15.2 cm down, giving a block of 2.15 cm wide by 1.9 cm tall. The aspect ratio is 1.132, so the blocks are meaningfully wider than they are tall. These are measurements from one swatch, not a standard: yours will differ.
Example 1 — chart to finished size. A chart of 40 columns and 55 rows. Width is 40 × 2.15 = 86 cm; height is 55 × 1.9 = 104.5 cm. That is 2,200 blocks worked over 94 diagonals.
Example 2 — what assuming square blocks would have cost. Take the block width of 2.15 cm and use it for both directions, as you would if you measured once and assumed square. Height comes out at 55 × 2.15 = 118.25 cm instead of 104.5 cm — an overestimate of 13.8 cm on a blanket about a metre long, from a single unexamined assumption.
Example 3 — target size to chart size. For a blanket about 120 cm by 150 cm: columns = 120 ÷ 2.15 = 55.81, rows = 150 ÷ 1.9 = 78.95. Rounding gives 56 × 79 blocks, which multiplies back to 120.4 cm by 150.1 cm — close enough, and now known rather than hoped for.
Common C2C Chart Mistakes
Assuming a block is square. The single most expensive assumption on this page, because the error is multiplied by every row of the chart.
Measuring one block. A block is a few centimetres across; a tape read to the nearest half centimetre is a large fraction of that. Measure several and divide.
Reading the chart in rows. C2C is worked in diagonals. Reading straight across produces a mirrored or scrambled image.
Expecting a square chart to give a square blanket. It will not unless the blocks are square.
Swatching in a different yarn from the project. The block measurement is a property of yarn, hook and tension together. Change any of them and remeasure.
Forgetting the chart is only the picture. Border, edging and joining are all worked after it and all add to the finished dimensions.
Use the C2C Blanket Calculator
Once you have measured a block, the C2C blanket calculator will take your block size and target dimensions and return the grid you need, so you do not have to run the divisions and the rounding by hand.
Alongside it: the gauge swatch calculator for the stitch and row densities behind the block, the yarn yardage calculator for estimating how much yarn a project of that size will take, and the crochet blanket size guide for standard dimensions to aim at before you fix a grid.
Frequently Asked Questions
What does one square on a C2C chart represent?
One block — the small cluster of three stitches and a chain space that C2C is built from. The square tells you that a block goes there and what colour it should be. It does not tell you how big the block will come out, which is a property of your yarn, hook and tension rather than of the chart.
Are C2C blocks square?
Often not. Chart cells are drawn square because a chart is a counting grid, but a worked block is usually a little wider than it is tall. In the swatch used on this page a block measures 2.15 cm across and 1.9 cm down. Treating that block as square would put a 40 by 55 chart 13.8 cm out on height alone.
How do I work out the finished size of a C2C chart?
Count the columns and rows of the chart, measure a block in each direction, then multiply: columns by block width for the finished width, rows by block height for the finished height. Keep the two sums separate rather than measuring one block and using it for both.
How many blocks are in a C2C chart?
Columns multiplied by rows, the same as any rectangular grid. The diagonals do not change that total, only the order the blocks are worked in. A 12 by 7 grid is 84 blocks however you work it.
Why does my C2C blanket come out the wrong size?
Most often because the block measurement came from a single small block. An error in that one measurement is carried into every block of the project. Measuring across several blocks and dividing shrinks the same error by the number of blocks you measured across.
Does a square chart make a square blanket?
Only if your blocks are square, which they usually are not. A 50 by 50 chart worked at the block size used here finishes about 107.5 cm by 95 cm — noticeably wider than it is tall, from a perfectly square grid.
How many diagonals will I work?
Columns plus rows minus one. A 12 by 7 grid takes 18 diagonals: 7 while the piece widens, 5 while it holds its full width, and 6 while it narrows again. A square grid has no holding phase, because there is no longer side to cross.
The relationships on this page are arithmetic: multiplication, division and a counting argument about diagonals, each verified programmatically rather than asserted. The block measurements used in the examples come from one swatch and are illustrative — there is no standard C2C block size and no standard block aspect ratio, because both depend on yarn, hook and tension. Every diagram here is an original example grid drawn for this page; no published chart or graphghan pattern is reproduced.