C2C Crochet Blanket Calculator
Corner-to-corner is worked on the diagonal, so a 40×50 chart is 89 rows, not 50. Plan blocks, yarn, rows and time.
Your 50-row graphgan is 89 rows
This one catches everybody, and it is not a subtlety — it is off by nearly a factor of two. Corner-to-corner is worked on the diagonal, so a "row" is a diagonal of the chart, not a horizontal line of it. A grid W blocks wide and H deep has
W + H − 1 rows
because that is how many distinct diagonals a grid has. Not H. So the reasonable sounding estimate — "it's 50 rows, I manage five rows an hour, that's ten evenings" — is wrong by 78% before you start.
| Piece | Blocks | Rows you'd guess | Rows it is | Out by |
|---|---|---|---|---|
| Coaster | 6×6 | 6 | 11 | +5 (83%) |
| Cushion front | 20×20 | 20 | 39 | +19 (95%) |
| Baby blanket | 30×40 | 40 | 69 | +29 (73%) |
| Lap blanket | 40×50 | 50 | 89 | +39 (78%) |
| Throw | 50×65 | 65 | 114 | +49 (75%) |
| Queen bedspread | 60×80 | 80 | 139 | +59 (74%) |
Why a square blanket feels worse than a rectangle
The rows are not the same length as each other. Diagonal d holds whichever cells satisfy x+y=d, so the row lengths rise, plateau and fall — and both ends of that are exact: the longest row is min(W, H) blocks, and the number of rows at that full length is |W − H| + 1.
Put W = H and the plateau collapses to a single row. A square blanket increases for half the project and decreases for the other half, meeting at one enormous row where every block in the width is on the hook at once — and that is the row where a square C2C feels like it will never end. A long rectangle spreads the same work over a plateau of many identical rows, which is duller but far less demoralising. The total is W × H either way, so the block count cannot tell you this. The row profile can.
Planning notes
- Measure the block, do not look it up. A C2C block is a chain-3 and three double crochet, and its finished size depends on your yarn and hook exactly as any gauge does. Work a small square, measure across several blocks and divide.
- Blocks round outward. Ask for a 50-inch width at 1.5-inch blocks and you get 34 blocks, which is 51 inches. A blanket an inch over is a blanket; an inch under is a place mat.
- Yarn per block is the honest way to estimate yarn. Work ten blocks, unravel them, measure. It knows your tension and your yarn, which no chart does.
- A chart's rows are not C2C rows. If you are working from a pixel chart, the chart is in grid rows and you will be reading it diagonally. Most people mark the diagonals on the chart before starting, and everyone who doesn't wishes they had.
- Colour changes cost more on the diagonal. A shape that looks like a clean horizontal band on the chart is spread across many diagonals, so it produces far more yarn joins than it appears to. Simple, chunky designs work far better than fine detail.
How to use
- Give a block count, or a finished size and your block size.
- Measure your block from a swatch rather than looking it up.
- Read the row count — it is W + H − 1, not the height.
- Add yarn per block and a working rate for yarn and time estimates.
Frequently asked questions
How many rows is a C2C blanket?
W + H − 1, where W and H are the blocks across and down. C2C is worked on the diagonal, so a row is a diagonal of the chart rather than a horizontal line of it, and a grid has that many distinct diagonals. A 40 by 50 chart is 89 rows, not 50 — a 78% underestimate if you count down the side.
How many blocks do I need for a blanket?
Finished size divided by your block size, rounded up in both directions. The rounding matters: at 1.5-inch blocks a 50-inch width comes to 34 blocks, which is 51 inches. Round outward, because a blanket an inch over is a blanket and an inch under is a place mat.
How big is a C2C block?
It depends on your yarn and hook, so measure it rather than looking it up. A block is a chain-3 and three double crochet, and its finished size is a gauge measurement like any other. Work a small square, measure across several blocks and divide — measuring one block is measuring your rounding error.
Why does a square C2C blanket feel endless?
Because the rows are not the same length and a square has the worst possible profile. The longest row is min(W, H) blocks and the number of rows at that length is |W − H| + 1 — so for a square that plateau collapses to a single row, where every block in the width is on the hook at once. A long rectangle spreads the same work over many identical rows.
How much yarn does a C2C blanket take?
Blocks times yarn per block. Get the second figure by working ten blocks, unravelling them and measuring, which accounts for your tension and your yarn in a way no chart can. Buy the whole quantity in one dye lot, because a blanket is exactly the kind of large flat surface where a lot change shows.
Can I use a pixel chart directly?
You can, but the chart is drawn in grid rows and you will be reading it diagonally, which is the single most common place people lose their position. Mark the diagonals on the chart before you start. Everyone who skips that step wishes they had not.
Why do colour changes cost more in C2C?
Because a shape that reads as a clean horizontal band on the chart is spread across many diagonals, so it produces far more yarn joins than it looks like it should. Chunky simple designs work well in C2C; fine detail turns into an evening of weaving in ends.
Does this send anything anywhere?
No. Everything is calculated in your browser and nothing is stored or uploaded.
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