Tools
Hat & Top-Down Raglan Sweater Calculator
Choose a size from newborn to 5XL or enter your own measurements, add your gauge and yarn, and get a complete top-down raglan plan with a scale drawing of the yoke and the exact number of balls for the whole sweater. The second tab sizes beanies and slouchy hats from preemie to large adult.
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Body measurements: Knotions standard measurement charts (women XS–3XL, men, children, babies). Head sizes and hat heights: EasyCrochet hat size chart. Ease categories follow the Craft Yarn Council fit guide.
How it works: the math behind the tool
Raglan: the neck opening (π × back-neck width from the standard chart, × 1.5 for a boat neck) times your stitches per cm gives the starting chain, adjusted so the back and front are equal and, for cardigans, the front splits into two equal halves. After the 4 corner stitches, the rest is split 1/3 back, 1/3 front and 1/6 for each sleeve.
Each raglan increase round adds 2 stitches to each piece next to the 4 raglan lines. The body increases until half the finished chest (chest + ease) is reached or the armhole depth runs out; the remaining width becomes underarm chains. Sleeves increase only as much as needed for the upper arm measurement plus proportional ease.
Starting chain ≈ π × neck width × sts/cm · Crown ⌀ = (head × 0.90) ÷ π
Hats: hat circumference = head × 0.90 for a fitted beanie (10 % negative ease for elasticity), crown diameter = hat circumference ÷ π, and the last increase round is the multiple of 6 (sc), 8 (hdc) or 12 (dc) closest to circumference × stitches per cm. Yarn uses the same calibrated model as our yarn calculator with a 10 % margin.
Last updated: November 7, 2026
Frequently asked questions
How do I calculate a top-down raglan for crochet?
Measure the neck opening and multiply it by your stitches per cm to get the starting chain. Keep 4 stitches for the raglan corners and split the rest 1/3 back, 1/3 front and 1/6 per sleeve. Increase 8 stitches per round (2 per raglan line) until the body reaches half your chest plus ease at the armhole depth, then add underarm chains.
How many balls of yarn do I need for a crochet sweater?
It depends on size, ease, stitch and yarn: a women's M sweater in worsted weight often needs 900–1,300 m. Select your size, stitch and yarn in the calculator to get grams, meters and the exact number of balls, rounded up and with a 10 % safety margin.
How do I calculate the crown of a crochet hat?
Multiply the head circumference by 0.90 for a snug beanie, divide by π to get the crown diameter, and increase in rounds of 6 (sc), 8 (hdc) or 12 (dc) stitches until the round has about hat circumference × your stitches per cm. Then work even until the hat reaches its total height.
What head size and hat height should I use?
Typical head circumferences are 35.5 cm for a newborn, 43 cm for a baby, 48 cm for a toddler, 51 cm for a child and 56 cm for a medium adult, with total heights of about 12.5, 15.5, 18, 20.5 and 23 cm. The calculator includes every age from preemie to extra-large adult.