C2C Blanket Calculator
Last updated: March 2026
Plan your corner-to-corner crochet blanket with exact block counts, diagonal rows, and yardage estimates from your gauge swatch.
Why You Need a C2C Calculator
Corner-to-corner crochet creates stunning blankets, but the diagonal construction makes sizing tricky. Unlike traditional row-by-row crochet where you simply count stitches for width, C2C builds block by block at an angle. Without a calculator, figuring out how many blocks you need — and how many diagonal rows that translates to — involves math that is easy to get wrong.
This calculator takes the guesswork out of C2C planning. Enter your gauge swatch measurements and desired blanket dimensions, and it tells you exactly how many blocks wide and tall to work, how many diagonal rows from start to finish, and how much yarn you will need. Plan with confidence before you pick up your hook.
What Is Corner-to-Corner (C2C) Crochet?
C2C is a crochet technique where you work diagonally across the fabric. Each unit — called a block or tile — is typically a small cluster of chain stitches and double crochets. You start with one block in a corner, add one block per diagonal row on the increase side until you reach the maximum width, then decrease back down to a single block in the opposite corner.
The technique is beloved for graphgan blankets (blankets with pixel-art images), because each block acts like a pixel. It also produces a beautiful texture with subtle diagonal lines. C2C works up quickly once you get the rhythm, and the small, repetitive blocks make it an excellent travel or TV project.
Because C2C blocks are often not perfectly square — they tend to be slightly wider than they are tall, or vice versa depending on your yarn and tension — measuring a gauge swatch in both directions is essential for accurate sizing. This calculator accounts for that asymmetry automatically.
How the C2C Calculator Works
The calculator starts with your gauge swatch. You crochet a small test piece (at least 5 by 5 blocks), measure its width and height in inches, and enter those along with the block counts. The calculator divides to find the width and height of each individual block.
Next, it divides your desired blanket dimensions by the per-block measurements and rounds to the nearest whole number. This gives you the number of blocks wide and blocks tall. The total block count is simply blocks wide times blocks tall.
The diagonal row count — how many rows you work from the first corner to the last — equals blocks wide plus blocks tall minus one. If you provided a yarn-per-block measurement, the calculator multiplies total blocks by that value, converts inches to yards, and adds a 10 percent buffer for tails and joining.
Measure a C2C gauge swatch in blocks, then enter your desired blanket size. We'll calculate block counts, diagonal rows, and yardage.
Gauge Swatch
Desired Blanket Size
Common Blanket Sizes
| Size | Dimensions | Use |
|---|---|---|
| Baby | 30″ × 36″ | Stroller, crib |
| Throw | 50″ × 60″ | Sofa, lap blanket |
| Twin | 66″ × 90″ | Twin bed |
| Full | 80″ × 90″ | Full / double bed |
| Queen | 90″ × 100″ | Queen bed |
C2C Tips
- Swatch at least 5×5 blocks for an accurate gauge. Smaller swatches magnify measurement errors.
- C2C blocks are not always square. Measure both width and height separately — they often differ.
- The diagonal grows fast, then shrinks. The widest diagonal row has as many blocks as the shorter side of your blanket.
- Border adds size. If you plan to add a border, subtract its width from your target dimensions before calculating.
How to Use the C2C Calculator
Start by crocheting a gauge swatch of at least 5 by 5 blocks using your chosen yarn and hook. Measure the width and height of the swatch in inches. Enter the block counts and measurements into the gauge section of the calculator.
Then enter your desired blanket width and height in inches. The calculator converts these to block counts and shows you the actual finished dimensions after rounding. If the actual size differs from your target by more than an inch or two, adjust your target or try a different hook size to change your block dimensions.
For yardage estimation, crochet one complete block, unravel it, and measure the length of yarn in inches. Enter this in the optional yarn-per-block field. The calculator uses this to estimate total yardage with a 10 percent buffer for safety. If you skip this field, you will still get all the block and row counts — just not the yardage estimate.
Understanding Your Results
The layout shows your blanket as X blocks wide by Y blocks tall. The actual finished dimensions may differ slightly from your target because block counts must be whole numbers. Review the actual dimensions shown in the results and decide if the rounding is acceptable.
The diagonal row count tells you how many rows you will work from start to finish. On the increase half, you add one block per row. On the decrease half, you remove one block per row. For rectangular blankets, there is also a middle section where you increase on one end and decrease on the other to maintain the row length.
The yardage estimate includes a 10 percent buffer for tails, color changes, and minor tension variations. If you are doing a multi-color graphgan, you will need to calculate yardage per color based on how many blocks each color occupies in your chart. The total yardage shown assumes a single color.
Pro Tips
From 30+ years of fiber arts experience
- ✓C2C blocks are almost never perfectly square. Always measure your swatch in both directions — do not assume a 2-inch-wide block is also 2 inches tall.
- ✓For graphgan blankets, subtract your planned border width from the target dimensions before calculating blocks. The border adds to the finished size.
- ✓Use stitch markers to count blocks every 10 rows on long diagonal rows. It is easy to lose count on rows with 50 or more blocks.
- ✓When changing colors frequently (as in a graphgan), carry unused colors along the top of the row rather than cutting and rejoining. This saves yarn and reduces the number of ends to weave in.
References & Standards
- Craft Yarn Council — Yarn Weight System — Industry-standard yarn weight categories and gauge ranges
- Craft Yarn Council — Needle & Hook Sizes — Standard sizing charts for knitting needles and crochet hooks
- Ravelry — Yarn database, pattern library, and community for fiber artists
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Frequently Asked Questions
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