How to use the gauge calculator
- Knit or crochet a swatch around 6 inches square in the yarn and stitch you plan to use. Wash and block it.
- Lay it flat and count the stitches across a measured width in the middle. Count rows down a measured height too if your pattern gives row counts.
- Enter the gauge printed on the pattern, then the stitch or row count you want to convert, such as the cast on or the number of rows to the armhole.
- If the stitch pattern repeats, enter the multiple and any extra edge stitches. Add a target width if you are designing your own piece.
How gauge conversion works
The pattern's stitch count is really a width. At 20 stitches per 4 inches, 200 stitches is 40 inches. To get 40 inches at your gauge, you multiply the width by your own stitches per inch. The shortcut is the ratio of the two gauges: your stitches divided by the pattern's stitches.
Rows work the same way with row gauge. You can convert the shaping too. Say the pattern decreases every 6 rows and your row gauge is 10 percent tighter. Decreasing every 6 or 7 rows then keeps the shaping over the same length.
Formulas
- Your stitches per inch = stitches counted ÷ width measured.
- New stitch count = pattern stitches × your gauge ÷ pattern gauge.
- New row count = pattern rows × your row gauge ÷ pattern row gauge.
- Width if you keep the pattern's count = pattern stitches ÷ your stitches per inch.
- Stitches for a target width = width × your stitches per inch.
Worked example: a sweater body
A pattern asks for 20 stitches and 28 rows per 4 inches and has you cast on 200 stitches for a 40 inch body. Your swatch gives 22 stitches and 30 rows per 4 inches, which is 5.5 stitches per inch.
If you cast on 200 anyway, the body measures 200 ÷ 5.5 = 36.4 inches, about 9 percent smaller. To get 40 inches, cast on 200 × 22 ÷ 20 = 220 stitches. A section the pattern works over 140 rows takes 140 × 30 ÷ 28 = 150 rows at your gauge.
How much a small gauge difference changes the size
The pattern below asks for 20 stitches per 4 inches and casts on 200 stitches for a 40 inch body. Each row shows what happens at a nearby swatch gauge if you keep the pattern's count, and the count the calculator gives to stay at 40 inches.
| Your gauge (sts per 4 in) | Width with 200 sts | Change | Cast on for 40 in |
|---|---|---|---|
| 18 | 44.4 in | +11.1% | 180 |
| 19 | 42.1 in | +5.3% | 190 |
| 19.5 | 41.0 in | +2.6% | 195 |
| 20.5 | 39.0 in | -2.4% | 205 |
| 21 | 38.1 in | -4.8% | 210 |
| 22 | 36.4 in | -9.1% | 220 |
Half a stitch per 4 inches moves this body by about an inch. Two stitches per 4 inches moves it by 3.6 to 4.4 inches. Tin Can Knits gives the same case from the other side: 200 stitches at 4.5 stitches per inch instead of 5 makes a 40 inch sweater about 44.5 inches. The calculator gets 44.4 inches. Dummies works a smaller piece: a 90 stitch front is 20 inches at 4.5 stitches per inch and 22.5 inches at 4. So the whole sweater grows by about 5 inches.
Gauge in centimeters
Metric patterns give gauge per 10 cm. The math is the same ratio. KnytStudio uses this example: 100 stitches at 22 per 10 cm make a piece 45.5 cm wide. If your swatch has 20 stitches per 10 cm, cast on 100 × 20 ÷ 22, which rounds to 91 stitches. The calculator gives 91 as well. Switch the units in the form and type your counts per 10 cm.
Swatch size and blocking
KnytStudio suggests a swatch at least 15 by 15 cm (6 by 6 inches) and measuring only the central 10 cm, away from the edges. Tin Can Knits measures twice: once while knitting and again after washing and drying. Its reason: "many yarns change gauge quite drastically with blocking." Enter the blocked numbers here, because you will wash the finished piece too.
If your swatch is off, KnytStudio notes that some knitters need to go up or down 2 to 3 needle sizes before they match a pattern. More stitches than the pattern means your stitches are small, so try a larger needle; fewer means a smaller needle. For step-by-step help with counting, see the guide on how to measure gauge.
When gauge matters less
For fitted garments such as sweaters and socks, the table above shows why gauge matters. Tin Can Knits notes that for a cowl, scarf, shawl, blanket or hat, a slight size difference is less important or less visible. Gauge still sets the finished size, and with it the yarn the piece uses. The blanket yarn calculator works that out from your own swatch.
When to change the numbers and when to change needles
Going up or down a needle or hook size is the standard fix, and it keeps every number in the pattern correct. Converting the counts makes more sense when you like the fabric your swatch has. It also helps when you swap in a yarn of a different weight, or when the pattern only comes in sizes that fall between yours.
Converting means more work in shaped patterns. Every cast on, pick up and decrease count needs the same conversion, so write the new numbers on the pattern as you go.
Tips for measuring gauge
- Count half stitches. Half a stitch over 4 inches adds up to about an inch on a 40 inch sweater.
- Measure in two or three places and average them.
- Swatch in the round if you work the project in the round. Many knitters purl looser than they knit, so flat and round gauge can differ.
- Check your gauge again a few inches into the project. Tension often relaxes once you settle in.