1. Decide the size
Start from the use: a lovey or car-seat blanket, a baby blanket, a throw for the sofa or a bed blanket. Measure the cot, bed or sofa, or use a common size such as 30 × 36 inches for a baby blanket or 50 × 60 inches for a throw.
Here are common blanket sizes worked out as graphs, at worsted gauge:
| Blanket | Size | Graph | Blocks | Diagonal rows | Yarn |
|---|---|---|---|---|---|
| Lovey | 12 × 12 in | 12 × 12 | 144 | 23 | 130 m (142 yd) |
| Pram or car seat | 24 × 30 in | 24 × 30 | 720 | 53 | 648 m (709 yd) |
| Baby | 30 × 36 in | 30 × 37 | 1,110 | 66 | 999 m (1,093 yd) |
| Lap throw | 40 × 50 in | 41 × 51 | 2,091 | 91 | 1,882 m (2,058 yd) |
| Sofa throw | 50 × 60 in | 51 × 61 | 3,111 | 111 | 2,800 m (3,062 yd) |
| Twin bed | 66 × 90 in | 67 × 91 | 6,097 | 157 | 5,487 m (6,001 yd) |
At 2.5 cm per block (worsted yarn, 5 mm hook) and 0.9 m of yarn per block, before the border. Your swatch decides both numbers.
2. Measure a block
Crochet a swatch of about 10 × 10 blocks with your yarn and hook, block it if you will block the blanket, and measure it. Divide by 10 to get one block. Worsted yarn with a 5 mm hook often gives blocks close to 25 mm, but tension varies a lot between crocheters.
3. Work out the graph size
Divide the blanket width and height by the block size. The C2C blanket size calculator does this for you, and also gives the total number of blocks, the number of diagonal rows and a yarn estimate. At 25 mm blocks, a 30 × 36 inch blanket is 30 × 37 blocks: 1,110 blocks and 66 diagonal rows.
4. Estimate yarn
Our tools assume about 0.9 m of worsted yarn per block, so 1,110 blocks need roughly 1,000 m. That is deliberately generous: Square One Crochet Designs lists about 284 yards for an 18-inch C2C square, which works out at roughly 0.7 to 0.8 m per block. Weigh your swatch to check: if 100 blocks use 45 g, the blanket needs about 500 g, plus a border. Buy the main colour from one dye lot, with a spare ball.
Yarn by colour
The total is only half the story: you buy yarn colour by colour. Each colour’s share is its number of blocks times the yarn per block. Here is a real graph from our library worked out that way:
| Colour | Blocks | Amount |
|---|---|---|
| Snow | 676 | 608.4 m |
| Hot Pink | 620 | 558 m |
| Blush | 304 | 273.6 m |
| Total | 1,600 | 1,440 m |
To turn metres into balls, divide by the metres on the ball band and round up. Main and background colours use far more than accent colours, so they are the ones to buy from a single dye lot with a spare ball; for accents a single ball is usually plenty.
5. Make the graph
In the C2C pattern maker, set the width in blocks, choose the number of colours and load your photo or design. Keep colour counts modest, and use the editor to remove single stray blocks: each one means a separate tiny piece of yarn. The written diagonal rows tell you how many blocks of each colour to work in every row.
6. Organise the yarn
Wind a bobbin or small ball for each colour area rather than carrying yarn across the back. Label bobbins with the colour letter from the key. The guide to reading C2C graphs explains how increases and decreases work at the corners.
Common planning mistakes
| Mistake | What happens | Avoid it by |
|---|---|---|
| Skipping the swatch | The blanket comes out a different size from the plan | Swatching 10 × 10 blocks and measuring after blocking |
| Too many colours | Dozens of bobbins and ends to weave in | Keeping to about 6–12 colours and merging near-identical shades |
| Single stray blocks | Each one needs its own bobbin or a cut end | Raising confetti cleanup and tidying in the editor |
| Buying the main colour in batches | Visible stripes where the dye lot changes | Buying all of it at once, plus a spare ball |
| Forgetting the border | Running short at the very end | Allowing extra yarn for the border and tails; the 0.9 m default includes some margin |
Before you start
- Check the gauge again after a few rows of the real blanket.
- Photograph the graph on your phone and mark progress in the stitch tracker.
- New to the technique? Start with the C2C basics on a small square.