What this calculator works out
This calculator estimates the yarn a crochet project needs from its finished area and a metres-per-area figure taken from a swatch, adding an allowance.
Working from area rather than stitch count is the practical approach for crochet, where stitch heights vary enormously between the basic stitches and pattern yardages are less standardised than in knitting.
Enter your details
Before you estimate
- Get the metres per 100 cm² figure from a swatch: work a 10 by 10 cm square, unravel it and measure the yarn used.
- The figure is stitch-specific. Double crochet uses considerably more yarn per area than treble, which is taller and more open.
- Crochet generally uses more yarn than knitting for the same area — commonly a third more, and more again for dense stitches.
- The allowance covers dye lots, tension drift and the ends you weave in. 15% is a reasonable minimum.
Crochet stitches wrap the yarn around itself more than knitted stitches do, so more length goes into the same area of fabric. Estimating a crochet project from a knitting pattern's yardage, or from a general rule, reliably comes up short — which is why the swatch measurement is worth the ten minutes it takes.
How this calculator works
Area times a measured rate, plus an allowance:
Area = width × length
Yarn = area ÷ 100 × metres per 100 cm²
Total = yarn × (1 + allowance ÷ 100)Dividing the area in square centimetres by 100 gives the number of 100 cm² units, which the swatch rate then converts to metres. The result is a length, so divide by the metres per ball to get a ball count.
Worked example: a metre square
Using the default figures — 100 by 100 cm at 3.5 m per 100 cm², with a 15% allowance:
- Project area: 1 m²
- Yarn before allowance: 350 m
- Total to buy: 402 m
402 metres for a square metre of fabric at that rate. Swap to a denser stitch measuring 5 m per 100 cm² and it becomes 575 m — 43% more for the same finished size. The stitch choice matters more than the dimensions, which is why the swatch figure has to come from the stitch you will actually use.
Common mistakes
- Using a knitting yardage for a crochet project. Crochet uses substantially more.
- Swatching in a different stitch. The rate is stitch-specific.
- Skipping the allowance. Dye lots make running short expensive.
- Measuring the swatch without unravelling it. The measurement is of yarn used, not fabric made.
- Forgetting the border. Edging a blanket can add 10% or more.
Frequently asked questions
How do I measure yarn used in a swatch?
Work a 10 by 10 cm square in the intended stitch and yarn, fasten off, then unravel it and measure the length with a tape. Alternatively weigh the swatch and compare against the ball's stated weight and length, which avoids unravelling and is accurate enough for planning.
How much more yarn does crochet use than knitting?
Commonly around a third more for a comparable fabric, and considerably more for dense stitches such as single or double crochet worked tightly. Taller, more open stitches close the gap. The variation between stitches is large enough that a single rule of thumb is unreliable — which is the argument for swatching.
Does hook size change the yarn used?
Yes, in the same way needle size does in knitting. A larger hook produces a looser, more open fabric that covers more area for the same yarn, so the metres per 100 cm² falls. Swatching with the hook you intend to use captures this automatically.
What about a granny square blanket?
Work one complete square, unravel or weigh it, and measure its finished dimensions. That gives a per-square yarn figure and a per-square area, which multiply straightforwardly to the whole blanket. It is more reliable than an area estimate because the joining and the corners are already included.
Is what I enter stored?
No. Figures are processed in your browser and never transmitted or retained.
Related tools
References
- GOV.UK — textile labelling and consumer information requirements
- MoneyHelper — budgeting for craft materials
Sources are checked at publication and can change — how I choose and check references.