You have found the pattern of your dreams, and then it says "US 8", "20 sts per 4 inches" and "875 yds". Or maybe the other way around, confused by the metric system? Here is what all of it means, starting with the one you came for: US 8 is 5.0 mm, and the full knitting needle conversion chart is right below.
The short version of the whole post: in the metric system the number is the thickness in millimeters. In the US system the number is arbitrary, and higher just means thicker. Everything else on this page (gauge, yarn amounts, body measurements) is ordinary arithmetic once you know which system you are reading.
Knitting needle conversion chart 🧵
| Metric (mm) | US | UK / Canadian |
|---|---|---|
| 1.5 mm | 000 | – |
| 1.75 mm | 00 | – |
| 2.0 mm | 0 | 14 |
| 2.25 mm | 1 | 13 |
| 2.5 mm | 1½ | – |
| 2.75 mm | 2 | 12 |
| 3.0 mm | 2½ | 11 |
| 3.25 mm | 3 | 10 |
| 3.5 mm | 4 | – |
| 3.75 mm | 5 | 9 |
| 4.0 mm | 6 | 8 |
| 4.5 mm | 7 | 7 |
| 5.0 mm | 8 | 6 |
| 5.5 mm | 9 | 5 |
| 6.0 mm | 10 | 4 |
| 6.5 mm | 10½ | 3 |
| 7.0 mm | – | 2 |
| 7.5 mm | – | 1 |
| 8.0 mm | 11 | 0 |
| 9.0 mm | 13 | 00 |
| 10.0 mm | 15 | 000 |
| 12.0 mm | 17 | – |
| 15.0 mm | 19 | – |
Two things this chart cannot tell you. Some sizes only exist in one system: 7.0 and 7.5 mm have no US equivalent at all, which is why a Norwegian pattern can ask for a needle an American shop does not stock. And at the thick end the sources genuinely disagree: US 17 is marked 12 mm by some manufacturers and 12.75 mm by others. When a needle carries both numbers, trust the millimeters.
Metric and imperial, in six lines 🌍
Metric (millimeters, centimeters, grams, meters) is used across Norway, the Nordics and most of Europe. Imperial (inches, ounces, yards) is used in the US and partly in the UK. These are the only conversions you actually need:
| From | To | How |
|---|---|---|
| Inches | Centimeters | Multiply by 2.54 |
| Centimeters | Inches | Divide by 2.54 |
| Yards | Meters | Multiply by 0.91 |
| Meters | Yards | Multiply by 1.09 |
| Ounces (oz) | Grams | Multiply by 28.35 |
| Grams | Ounces (oz) | Divide by 28.35 |
Gauge: 10 cm or 4 inches? 📏
European patterns give gauge per 10 cm. US patterns give it per 4 inches, which is 10.16 cm. That is a difference of 1.6 %, so in practice you can read the two numbers as the same. A pattern asking for 20 stitches per 4 inches is really asking for 19.7 per 10 cm.
| The pattern says | Per 10 cm |
|---|---|
| 12 sts / 4" | 11.8 sts |
| 16 sts / 4" | 15.7 sts |
| 18 sts / 4" | 17.7 sts |
| 20 sts / 4" | 19.7 sts |
| 24 sts / 4" | 23.6 sts |
| 28 sts / 4" | 27.6 sts |
| 32 sts / 4" | 31.5 sts |
The finer the yarn, the more that 1.6 % shows. On chunky yarn it is invisible; on sock yarn half a stitch per 10 cm becomes several centimeters across a whole body.
Measure your swatch over a wider area than 10 cm and divide back down: measuring over 20 cm and halving it halves your margin of error too. If swatching is the part you skip, our guide to gauge swatching is worth ten minutes.
And if you want to go the other way, from a gauge to the yarn that gives it, that is what the yarn weight chart is for.
Yarn amounts: grams, ounces, meters and yards 🧶
Length is the number that matters. Grams tell you nothing about how far a yarn goes: 50 g of fine silk mohair and 50 g of chunky wool are wildly different amounts of knitting.
| Yards | Meters |
|---|---|
| 100 yds | 91 m |
| 200 yds | 183 m |
| 220 yds | 201 m |
| 400 yds | 366 m |
| 875 yds | 800 m |
| 1000 yds | 914 m |
| 1500 yds | 1372 m |
| Grams | Ounces (oz) |
|---|---|
| 25 g | 0.9 oz |
| 50 g | 1.8 oz |
| 100 g | 3.5 oz |
| 200 g | 7.1 oz |
| 500 g | 17.6 oz |
A worked example. The pattern calls for 1000 yds. That is 914 m. Your yarn has 210 m per 50 g skein, so 914 ÷ 210 = 4.4 skeins. Round up to 5. You do not want to run out mid-decrease.
Swapping to a different yarn altogether? Our Yarn Swapper does the amount for you, and our guide to yarn substitutes covers picking the replacement.
Body and garment measurements 📐
No shortcuts here: multiply by 2.54 or divide by 2.54. But a few fixed points get you a long way:
| Inches | Centimeters |
|---|---|
| 28" | 71 cm |
| 30" | 76 cm |
| 32" | 81 cm |
| 34" | 86 cm |
| 36" | 91 cm |
| 38" | 97 cm |
| 40" | 102 cm |
| 44" | 112 cm |
| 48" | 122 cm |
Watch out for ease. US patterns often list both a bust measurement and a finished garment measurement, and the difference between them is ease. "4 inches of positive ease" means roughly 10 cm more width than your body. Always check which of the two a size chart is quoting, or your sweater ends up a size you did not choose.
Circular needles and cable lengths 🔁
Cable lengths come in two systems too, and here the numbers are rounded generously:
| Inches | Centimeters |
|---|---|
| 9" | 23 cm |
| 12" | 30 cm |
| 16" | 40 cm |
| 24" | 60 cm |
| 32" | 80 cm |
| 40" | 100 cm |
| 47" | 120 cm |
Rules of thumb to keep in your pocket 💡
- Inches to cm: multiply by 2.5 and add a touch
- Yards to meters: subtract about 10 %
- Meters to yards: add about 10 %
- 100 g is about 3.5 oz
- 4.5 mm = US 7 = UK 7
- Gauge per 4" and per 10 cm are the same number in practice
Frequently asked questions
What is US 8 in mm?
US 8 is 5.0 mm. It is one of the most common sweater needle sizes, sitting in the worsted and aran range. See all worsted and aran yarns →
Is US 7 the same as 4.5 mm?
Yes. US 7, UK 7 and 4.5 mm are the same needle, one of the few sizes where all three systems agree on the number, which makes it a useful anchor to remember.
Why do some needle sizes have no US number?
Because the two systems were built independently. 7.0 mm and 7.5 mm are ordinary sizes in Europe and simply have no slot in the US scale. If a pattern calls for one and you cannot find it, go to the nearest size and swatch. The gauge decides, not the label.
What is 20 stitches per 4 inches in 10 cm?
19.7 stitches per 10 cm. Four inches is 10.16 cm, so any per-4-inch gauge is about 1.6 % higher than the same gauge per 10 cm. On most yarns you can treat them as the same number.
How many skeins do I need if the pattern is in yards?
Convert the total to meters by multiplying by 0.91, then divide by the meters per skein on your ball band, and round up. 1000 yds is 914 m, which is five 210 m skeins.
Or skip the conversions entirely 🧶
The easiest option is not converting at all. In our design tool, you build the pattern in the units you already use, with the yarn you already own, your gauge and your needle size. Nothing to translate, because nothing was written in the other system to begin with.
You can see how the pattern generator works here, and if you are just getting started, our beginner tips are a good next stop.
Dreamknit Pro comes with a 14-day money-back guarantee, so you can try it on your own yarn before you commit.
