Measured projects
How to estimate yarn for a granny-square blanket
A blanket’s dimensions alone cannot tell you how much yarn it will use. Start with representative squares made in the intended yarn and stitch pattern, then scale their measured consumption to your planned grid.
Measure several representative squares
For identical single-colour squares, weigh a sample together and divide by the number of squares. Three squares weighing 24g give an average of 8g each. Weigh only the yarn and be consistent about tails. Your scale’s resolution and accuracy affect this estimate; weighing several squares can make a tiny display increment less significant relative to the sample.
Convert that weight using the same yarn’s label
If that yarn contains 200m per 100g, the label-based estimate is 8 ÷ 100 × 200 = 16m per square. Use the exact yarn’s length-to-weight ratio. Do not use the combined weight of a multi-colour square to guess the length of one colour, especially when the yarns have different specifications.
Choose the grid and multiply
A grid six squares across and eight down contains 48 squares. At 16m each, that is 768m before joining or a border. If each representative square measures 12cm, the simple unjoined grid measures 72 × 96cm. A join may add width, a border adds more, and the fabric may change with finishing. This calculation is not a finished-size guarantee.
Keep finishing yarn visible
Add a separately estimated length for the joining method and border you intend to use. Suppose you enter 60m in the same yarn and colour: 768 + 60 = 828m. If the border is a different colour, leave it out of that total and give it its own shopping row. Leaving the finishing field at zero explicitly excludes those requirements.
Move from an estimate to a purchase
With 200m per ball and no stash, 828m requires five balls. If you have 100m of usable matching yarn, the new purchase must cover 728m and rounds to four balls. The square planner transfers the length, while the shopping planner handles stash, packs and any allowance you deliberately choose. No allowance is added automatically.
When this method needs more work
Different motifs, variable square sizes, several colours, changing stitch patterns or inconsistent samples need separate measurements. Use your designer’s yarn quantities when those are available and relevant. If you change the yarn, hook or construction, recheck the sample rather than assuming the old consumption still applies.
Check before you move on
- Same yarn and stitch instructions throughout the sampled squares
- Only yarn on the scale; consistent treatment of tails
- Measured count and combined sample weight recorded
- Joining and border requirements kept separate
- Each colour rounded independently in the shopping list
Try it with your own numbers.
Estimate a square blanket from your own weighed samples, grid size and finishing allowance.
Plan my square grid ↗Common questions
Can I enter the weight of a multi-colour square?
Not as a single-colour requirement. Measure each colour’s consumption separately or use the designer’s quantities. The current square planner handles one yarn and colour at a time.
Are these blanket instructions?
No. The examples demonstrate an estimation method and have not been physically crocheted or tested as a pattern.
Keep planning
- Subtract the yarn you already own
- Calculate yarn separately for every colour
- Should I add an extra yarn allowance?
- Check your measuring and planning kit
These are planning methods, not physically tested crochet patterns. Read our method and editorial approach.