How to resize a vintage knitting pattern (the right way)

So you've found a gorgeous 1940s or 1950s sweater pattern. It comes in one size, a 34" bust, and you're a 42". It's very tempting to multiply every number by 42 ÷ 34 and cast on.

Please don't. That shortcut gets the width roughly right and almost everything else wrong.

Below is the method that does work, with one full example carried all the way through so you can swap in your own numbers.

Why multiplying goes wrong

42 ÷ 34 = 1.235, so scaling makes every count about 23.5% bigger. Around the bust, that's about right. The trouble is that bodies don't grow evenly. Here are two published sets of standard body measurements for a 34" and a 42" bust, side by side:

Ranges reflect differences between the size standards we checked; they're averages, not rules.

Scale everything and you get shoulders that slide off, armholes that gape, a body several inches longer than the designer meant, a neckline that's too wide and cuffs that flap. Shaping worked over rows (waist decreases, sleeve increases, the sleeve cap) lands in the wrong places too, because it was spaced for the original lengths.

The way out is to stop thinking in stitches and start thinking in measurements. In short:

1. Check your gauge (tension).
2. Draw a schematic of the original garment in inches or centimetres.
3. Decide the ease the original had and keep it.
4. Grade each measurement separately: bust, cross back, armhole depth, upper arm, neck, length.
5. Convert back to stitches and rows, then fit stitch-pattern repeats.
6. Re-space the shaping over the new lengths.

1. Gauge comes first

Every number in a pattern only means something at the stated gauge. Our example pattern says 7 stitches and 9 rows to 1 inch in stockinette (stocking stitch). That's about 27½ stitches and 35½ rows to 10 cm, a typical fingering (4-ply) gauge.

Knit a generous swatch. Wash and dry it the way you'll treat the finished garment, then measure. Say you get 7½ stitches per inch. The original 126-stitch back would then come out at 126 ÷ 7.5 = 16.8" instead of 18". That 1.2" difference doubles across front and back, and you haven't resized anything yet. Our gauge guide covers this properly.

2. Turn the original into a drawing

Go through the pattern and convert the key counts into measurements: stitches divided by stitches per inch, rows divided by rows per inch. For our 34" example at 7 sts and 9 rows per inch:

Sketch a rough outline of the back, front and sleeve and write these figures on it. From here on, that drawing is your real pattern.

3. Find the ease, and keep it

Ease is the gap between garment and body. This garment is 36" round and was written for a 34" bust, so it has 2" of positive ease. That's a neat, close fit, very typical of the 1940s and 1950s.

To keep the same look on a 42" bust, aim for 42 + 2 = 44" finished. Give yourself 6" of ease instead and you'd be making a different, boxier garment. There's more on this in how vintage knitwear should fit.

4. Grade one measurement at a time

Use your own measurements wherever you can. If you can't measure, size charts are a sensible place to start; the figures here lean on the published standards in the first table.

Bust width. 44" ÷ 2 = 22" per piece.

Cross back and shoulders. The body standards suggest about 2" more across the back between a 34" and a 42" bust. The original was about 13.1", so aim for about 15".

Back neck. Necks hardly grow. Add about ¼–½" and aim for about 5.4".

Armhole depth. Standards suggest roughly ¾–1" deeper, so go from 7" to 8". Scaling would give 7 × 1.235 = 8.6", which tends to gape at the underarm.

Upper arm. Take your body upper arm and add the original's sleeve ease. The original sleeve top (11.4") over a 10¼–10½" arm had about 1" of ease. For a 12–13" arm, that's 13–14"; we'll use 14" to be safe. At this size it happens to land close to the scaled figure, but upper arms vary a lot from person to person, so measure yours.

Wrist and cuff. Wrists barely change between sizes. Go from 8" to about 8½".

Length. Keep the designer's proportions. The original stops at the natural waist with a deep welt. Scaling 13" by 1.235 would give 16" and turn a waist-length sweater into a hip-length one. Add only what your own body needs: perhaps ½" for a slightly longer back waist, plus any bust room on the front (short rows are in our plus-size guide).

5. Back to stitches and rows

At 7 sts and 9 rows per inch, with the scaled figures alongside so you can see the difference:

Now check the sums. 33 + 38 + 33 = 104, and 154 − 104 = 50, so the armhole shaping has to remove 25 stitches each side. The original removed 17 each side (126 − 92 = 34), so you'll need more decreases. For example, bind off (cast off) a few more stitches at the start and work a few more decrease rows.

Stitch-pattern repeats. Say the design has an 8-stitch lace repeat plus 2 edge stitches. Check your number fits: 8 × 19 + 2 = 154. Here it fits neatly. If it doesn't, adjust by a few stitches or add plain stitches at the sides rather than breaking a motif. Keep the repeat itself as it is; never stretch a 6-row pattern to 7.

6. Re-space the shaping

Anything worked over rows has to be recalculated for the new counts.

Sleeve increases. The original went from 56 to 80 stitches: 24 stitches, or 12 increase rows (one each end). The new sleeve goes from 60 to 98 stitches: 38 stitches, or 19 increase rows, over the same 135-row length. Sleeve increases usually finish an inch or two below the underarm, so spread them over about 120 rows. 120 ÷ 19 = 6.3, so increase at each end of every 6th row 19 times (114 rows), then work the remaining 21 rows (about 2⅓") straight.

Sleeve cap. The cap has to fit the new armhole. Its height depends on armhole depth and on how the original cap was shaped, not on bust width. Measure the original cap's height and top width, keep its shape (a puffed 1940s cap stays puffed), and adjust the decreases so the cap edge roughly matches the new armhole edge. Scaling the cap by the bust ratio is the most common reason resized vintage sleeves don't sit right.

Neck and shoulder slope. Keep the angle of the shoulder slope by spreading the 33 shoulder stitches over the same number of short steps or bind-off rows as the original. Keep the front neck depth close to the original, too. It's a style feature.

Leave these alone

• Ribbing depth, welts and bands keep their vintage depth.
• The stitch pattern and its row repeat.
• Construction order: set-in sleeves stay set-in; a yoke stays a yoke.
• The character details: puffed caps, waist-length welts, neat collars.

Change those and you're designing a new garment. That's a lovely thing to do, but it isn't the one you fell for.

Before you cast on

• Swatch done, washed and measured
• Schematic of the original with measurements written on
• Original ease worked out and kept
• Bust, shoulders, neck, armhole depth, upper arm, wrist and length graded one at a time
• Stitch counts checked against repeats
• Sleeve cap checked against armhole
• Shaping re-spaced over the new rows

If you'd rather not do all this by hand, that's what our patterns are for. Each one is rebuilt from the original written instructions for your size, yarn and gauge, from US 4–24 / UK 8–28 (a 32–52 in bust), and every size is graded the way this guide describes rather than scaled. A knitter chose and checked every design, and if you get stuck, email support@vintagetomodernknits.com and a real person will reply.

Read next

• How to measure tension
• Plus-size vintage knitting
• Why vintage patterns go wrong
• Will it fit? tool

Last updated 2026-10-11.