Knitting guide
Elizabeth Zimmermann's percentage system explained
Updated by Khokhar Sab
Elizabeth Zimmermann's Percentage System (EPS) builds a whole sweater from one number, K: the body stitch count, found by multiplying your stitches per inch by the finished chest. The neck, sleeves, wrists and underarms are then set as percentages of K, such as 40 percent for the neck and 35 to 40 percent for the upper arm.
What Elizabeth Zimmermann's percentage system is
Elizabeth Zimmermann worked out a way to plan a sweater from proportions instead of a printed pattern. She called it an "unvention". Knitters now call it EPS, short for Elizabeth's Percentage System.
The idea is simple. Bodies are roughly in proportion, so the chest gives a fair estimate of the neck, upper arm and wrist. EPS writes each of those as a percentage of one number, and that number comes from your own gauge. Any yarn and any size work the same way.
Zimmermann lived from 1910 to 1999. Her Wikipedia entry describes EPS as still widely used by designers and dates her first book, Knitting Without Tears, to 1971. KnitPro's blog post on notable knitting godmothers names that book as the one that explains EPS but gives 1973, so sources differ on the year. Schoolhouse Press, founded in 1958, is now run by her daughter Meg Swansen.
The method is still in use. Schoolhouse Press describes its Weekend Raglan pattern as following EPS construction guidelines.
Find K, the number everything comes from
Zimmermann called the body stitch count K. You need two numbers to find it:
- Your finished chest: your chest measurement plus the ease you want. The guide to knitting ease covers how much to add.
- Your gauge in stitches per inch, measured from a washed swatch.
Multiply them. The Knit Picks tutorial on the percentage system uses 5 stitches per inch and a 50 inch sweater, so 5 × 50 = 250 and K = 250.
This guide uses the sweater calculator defaults instead. The chest is 37 inches with 3 inches of ease, at 20 stitches per 4 inches. The finished chest is 37 + 3 = 40 inches. The gauge is 20 ÷ 4 = 5 stitches per inch. So K = 40 × 5 = 200. The calculator rounds K to an even number so it splits evenly between front and back.
The EPS percentages
Knit Picks lists stitch counts for a yoke sweater with K = 250. Divide each count by 250 and you get the percentages below. The last column applies the same percentages to K = 200.
| Part | Percent of K | K = 250 | K = 200 |
|---|---|---|---|
| Neck | 40 | 100 | 80 |
| Upper arm (sleeve at the underarm) | 35 to 40 | 88 to 100 | 70 to 80 |
| Wrist | 20 to 25 | 50 to 62 | 40 to 50 |
| Stitches on hold at each underarm | 8 to 10 | 20 to 25 | 16 to 20 |
The percentages are rounded: 88 ÷ 250 is 35.2 percent and 62 ÷ 250 is 24.8 percent. Meg Swansen of Schoolhouse Press gives the same underarm range, placing 8 to 10 percent of the body stitches on holders at each underarm of a yoke knit in one piece.
The sweater calculator uses 40 percent for the neck and 8 percent for the underarm. You set the upper arm yourself, between 20 and 50 percent. The default is 35.
The drop shoulder version
Knit Picks gives EPS numbers for a second shape, the drop shoulder sweater, using the same K = 250. The wrist stays at 20 to 25 percent. The upper arm is much wider, and the neck can be narrower.
| Part | Percent of K | K = 250 | K = 200 |
|---|---|---|---|
| Wrist | 20 to 25 | 50 to 62 | 40 to 50 |
| Upper arm | 45 to 50 | 112 to 125 | 90 to 100 |
| Neck | 33 to 40 | 82 to 100 | 66 to 80 |
As before, the percentages are rounded from Knit Picks' counts: 112 ÷ 250 is 44.8 percent and 82 ÷ 250 is 32.8 percent. At K = 200, a drop shoulder sleeve starts with 90 to 100 stitches at the top, against 70 for the raglan below. The sweater calculator plans raglans only, so use these numbers by hand if you want a drop shoulder.
Worked example: a top-down raglan from K = 200
The calculator plans a raglan knit from the neck down. Here is how the percentages turn into steps.
1. Cast on the neck
40 percent of 200 is 80 stitches. Four of them become raglan "seam" stitches, one at each corner where a sleeve meets the body. The other 76 split into four sections: 13 for each sleeve, 25 for the front and 25 for the back. Check the sum: 13 + 13 + 25 + 25 + 4 = 80.
2. Increase along the raglan lines
Every other round, increase one stitch on each side of each seam stitch. That adds 8 stitches per round, 2 to each section. Work 21 of these increase rounds.
The body needs more stitches than the sleeves, so the calculator adds 8 more increase rounds that add 4 stitches to the body only. They sit on the plain rounds between the raglan increases, so they don't make the yoke deeper.
3. Separate the sleeves
After 42 rounds the needle holds 280 stitches: 83 front, 83 back, 55 on each sleeve and the 4 seam stitches. At 28 rounds per 4 inches, the yoke is 6 inches deep.
Put each sleeve on hold. Cast on 15 stitches under each arm and join the front and back. The body now has 83 + 83 + 4 + 15 + 15 = 200 stitches, which is K again.
Each sleeve picks up the same underarm stitches: 55 + 15 = 70 stitches, or 35 percent of K. The underarm cast on is 15 stitches (7.5 percent) instead of exactly 16, because the calculator uses it to bring the body back to exactly K.
4. Work the body and sleeves
Knit the body straight to the length you want. For each sleeve, decrease from 70 stitches down toward the wrist range of 40 to 50 stitches, which is 20 to 25 percent of K. Space the decreases along the arm.
EPS for a baby sweater
Proportions change with age, and EPS bends with them. In her Wee Aran measurement plan, Claudia Krisniski notes that Zimmermann advised slightly different percentages for an infant than for an adult. Her plan for a 3 month sweater uses:
- A 20 inch body at 5 stitches per inch, so K = 20 × 5 = 100.
- Sleeves at 35 percent of K: 35 stitches, or 7 inches around.
- A neck at 45 percent of K: 45 stitches, against 40 at the adult 40 percent.
The neck still has to pass over the baby's head, so even at 45 percent she adds an open neckband with buttons so the sweater goes over the head easily. She also found the standard yoke a little shallow and made hers deeper, as deep as the sleeve is wide.
Adjusting the percentages for fit
Knit Picks notes that you can adjust the formulas to follow current fashion. The percentages are a starting point, and real measurements should have the last word.
- For fuller upper arms, raise the sleeve to 38 or 40 percent. At K = 200 that gives 76 or 80 stitches.
- For a looser sweater, add ease to the chest. K grows, and every other count grows with it.
- For a closer cuff, aim for the low end of the wrist range and finish with ribbing.
To check any count, divide it by your stitches per inch. In the example, 70 ÷ 5 = 14 inches around the upper arm. If that is less than your arm measurement plus a little ease, raise the sleeve percentage. The same check works for the neck and wrist.
Gauge matters as much as the percentages. Every count above depends on 5 stitches per inch, so measure a washed swatch first. The guide on how to measure gauge shows how.
Sources and further reading
- Knit Picks: the percentage system.
- Schoolhouse Press: Meg Swansen on yoke sweaters.
- Wikipedia: Elizabeth Zimmermann.
- Wee Aran, part 2: a worked measurement plan.
Video tutorial
"Designing a Sweater Using Elizabeth Zimmermann's EPS // Casual Friday S05E28" by Roxanne Richardson, on YouTube. The video loads only when you press play.