Free guide

How much yarn do I need for a vintage pattern? (ounces, skeins and balls)

"9 ozs. 3-ply." "11 ozs. double knitting." Vintage patterns give yarn in ounces, and modern yarn comes in 25 g, 50 g or 100 g balls with a length printed on the band. Getting from one to the other is easy arithmetic. The catch is what the arithmetic leaves out, and that's the difference between finishing your cardigan and running out halfway down the second sleeve.

Ounces to grams

One ounce is 28.35 g. For knitting, call it 28 g and round up at the end.

Pattern says	Grams	50 g balls (before extra)
1 oz	28 g	under 1
2 oz	57 g	2
4 oz	113 g	3
6 oz	170 g	4
8 oz	227 g	5
9 oz	255 g	6
10 oz	283 g	6
12 oz	340 g	7
14 oz	397 g	8
16 oz (1 lb)	454 g	10

Two handy anchors: a modern 50 g ball is about 1¾ oz, and 100 g is about 3½ oz. A pattern written for 1 oz balls needs fewer, heavier modern balls, so you can't swap ball for ball.

The catch: you knit with length, not weight

Two yarns of exactly the same thickness can give very different lengths for the same weight. Three reasons:

Fibre density. Cotton and linen are heavier than wool, so 50 g of cotton is noticeably shorter than 50 g of wool of the same thickness. Acrylic and nylon are lighter, so 50 g goes further.
Spinning. A tightly twisted, dense yarn weighs more per metre than a soft, airy one.
Categories are ranges. One brand's 4-ply can be a little thicker than another's.

One large American yarn maker points out that 8 oz of one worsted-weight yarn can be as much as 100 yards longer or shorter than 8 oz of another. Old wartime and post-war wools, often tightly spun and quite dense, weren't necessarily the same length per ounce as today's softer yarns, and we don't have reliable lengths for most of them.

So treat an ounce figure from a vintage pattern as a starting point for an estimate, not a shopping list.

Rough lengths per ball

These are rough ranges for modern yarns, taken from yarn standards and real ball bands. Wool tends to sit in the middle, cotton at the short end, and synthetics or very fine merino at the long end.

Yarn weight (UK / US)	Metres per 25 g	Metres per 50 g	Metres per 100 g
2-ply / lace	150–200	300–400	600–800
3-ply / light fingering	100–150	200–300	400–600
4-ply / fingering	85–110	170–225	350–450
Sport / Australian 5 ply	60–90	125–175	250–350
DK / light worsted / Australian 8 ply	50–65	100–125	200–250
Aran / worsted / Australian 10 ply	30–50	60–100	120–200
Chunky / bulky	25–33	50–65	100–130

Sources don't all agree. The 3-ply range is especially wide: some charts put it at 400–500 m per 100 g, others at 500–600. A real 3-ply nylon-acrylic baby yarn we checked comes in at about 300 m per 50 g; a pure wool 3-ply could easily be shorter. Always go by the length printed on the ball you're actually buying.

Working it through: "9 oz of 3-ply"

A 1950s cardigan pattern asks for 9 oz of 3-ply for a 34-inch bust, and you want to use a modern 3-ply wool.

Convert to grams. 9 × 28.35 = 255 g.

Estimate the length the original used. We don't know the original yarn's exact length per ounce, so use the 3-ply range:

Short end: 255 g at 400 m per 100 g ≈ 1,020 m
Long end: 255 g at 600 m per 100 g ≈ 1,530 m

That's a big spread, and it's exactly why ounce figures need care.

Narrow it down. If your modern 3-ply is wool and knits to the same gauge (tension) as the pattern, the closest like-for-like comparison is by weight: about 255 g. That's 5.1 balls of 50 g, so round up to 6 balls.

If you're using a lighter synthetic 3-ply instead (say 300 m per 50 g), check by length too: 1,020–1,530 m ÷ 300 m ≈ 3.4–5.1 balls. Round up to 4–6 balls.

Add one ball on top. In this example, that means:

Wool 3-ply at matching gauge: 7 × 50 g balls.
Lighter synthetic 3-ply: 5–7 × 50 g balls, depending on where you think the original sat. When in doubt, buy the higher number.

Changing yarn weight? Start again. If you're knitting the same garment in 4-ply or DK instead of 3-ply (and recalculating the pattern for that gauge), the old ounce figure doesn't transfer. Roughly speaking, thicker yarn uses fewer metres but more grams for the same garment, so any estimate has to start from the area of fabric and your new gauge, and it will be rough. Our vintage yarn calculator converts the original amount into metres, which is the right starting point, but it can't predict a change of yarn weight. Buy generously, or ask your shop about returns.

Knitting a bigger or smaller size

Vintage patterns often came in only one or two sizes, so you may be scaling up or down. Yarn use roughly follows the area of fabric, which grows with both width and length. To estimate:

Find the pattern's finished bust (or the "to fit" bust plus the ease) and its body length.
Do the same for the size you're making.
Multiply the width ratio by the length ratio, then multiply the yarn amount by that.

Say the original is a 34-inch bust, 21 inches long, and needs 255 g. You're making a 40-inch bust, 23 inches long.

Width ratio: 40 ÷ 34 ≈ 1.18
Length ratio: 23 ÷ 21 ≈ 1.10
Combined: 1.18 × 1.10 ≈ 1.29
Yarn: 255 g × 1.29 ≈ 330 g, so 7 balls, plus one extra = 8 × 50 g balls.

It's an approximation. Sleeves, collars and deep ribbing don't scale quite the way the body does, and textured or cabled stitches eat more yarn. But it beats guessing, and it beats buying the original amount and hoping. For more on scaling vintage designs, see our guide to resizing vintage knitting patterns.

Running out is worse than having a spare

Buy at least one extra ball. That's standard advice for any pattern, and a vintage conversion carries more uncertainty than most.
Buy it all at once, from the same dye lot. Each dye batch can vary slightly in colour, and a ball from a different lot can show as a visible stripe, especially on a plain stockinette (stocking stitch) body. Check that the dye lot number matches on every ball band.
Keep the receipts and ball bands. Many shops accept unopened balls back (check the returns policy first), so a spare is often low-risk.
Weigh as you go. Kitchen scales are your friend. Weigh the back once it's done: the front of a sweater usually uses a similar amount, and the two sleeves together often use somewhere near the same again. If the back alone has used more than a third of your yarn, buy more now while the dye lot is still on the shelf.
Allow extra for contrast colours and trims. If a pattern says "½ oz contrast", that's only 14 g. Buy a full ball, or a 25 g ball if you can find one.

Where our patterns come in

With our patterns you're not converting an old ounce figure at all. Each one is rebuilt from the original written instructions for your size, yarn and gauge, from US 4–24 / UK 8–28 (32–52 in bust), and every design was chosen and checked by a knitter. If you're unsure how much to buy, email support@vintagetomodernknits.com and a real person will help you work it out.

Keep reading

Last updated 2026-10-11.