A Free Calculator · Your Swatch, Your Yarn · Updated 2026
How many stitches do you cast on?
Pattern gauge and your actual gauge are almost never the same number. Enter the
stitch and row counts from your own blocked swatch plus your target finished
dimensions, and the calculator returns the exact cast-on stitch count and total
row count for your yarn and needle combination. Every step of the math is shown.
Cast-on stitch count·Total row count·Stitches & rows per inch
Swatch and block first
This calculator is only as accurate as the gauge you enter. Measure from a blocked
swatch — not from stitches fresh off the needles. Blocking changes gauge by
10–20% for most natural fibers. Measure in the center of the swatch, away from
the edges, and count over the full 4-inch span. When in doubt, re-swatch on the
needle size above or below and compare.
Gauge to cast-on — stitches and rows for your dimensions
Enter your blocked swatch gauge and your target finished width and length. The results update as you type.
Your gauge swatch (measured blocked, over 4 inches)
sts / 4″
Count the stitches that fit in exactly 4 inches on your blocked swatch. Measure in the center, away from cast-on and bind-off edges.
rows / 4″
Count the rows that span 4 inches in height on the same blocked swatch. Row gauge controls finished length.
Your target finished dimensions
inches
The finished width you want after blocking. For garments, this is usually the body circumference or panel width from the schematic.
inches
The finished length you want after blocking — body length, sleeve length, or whatever dimension rows control in your project.
Cast on stitches
Cast-on stitches
Total rows
Stitches per inch
Rows per inch
The formulas, in full
Nothing here is a black box. These are the exact steps the calculator runs —
the same arithmetic you could do on the back of your pattern envelope. The only
judgment calls are the gauge numbers and dimensions you supply.
How each number is derived
1 — Stitches per inch (from your 4-inch swatch count)
These are approximate starting-point gauges from the
Craft Yarn Council weight system.
Your actual gauge will differ depending on fiber, needle material, needle size, and
your personal tension. Always swatch and block before trusting any number in this table.
Yarn weight
CYC number
Typical sts / 4″ (approx)
Typical needle size (US)
Common uses
Lace
0
32–42+ sts
000–1
Shawls, lace weight accessories, fine shawlettes
Fingering / Sock
1
28–32 sts
1–3
Socks, lightweight shawls, fine baby knits
Sport
2
24–26 sts
3–5
Baby items, lightweight sweaters, mittens
DK (Double Knit)
3
21–24 sts
5–7
Sweaters, hats, accessories — the most versatile weight
Worsted
4
16–20 sts
7–9
Sweaters, scarves, afghans — the most common weight in patterns
Bulky
5
12–15 sts
9–11
Chunky cowls, quick scarves, hats, blankets
Super Bulky
6
7–11 sts
13–17
Arm knitting, very chunky blankets, oversized cowls
All stitch counts are approximate and vary significantly with individual tension and needle size.
The same yarn knit by two different people can produce gauges that are two or more stitches apart
per 4 inches. These figures are useful for choosing a starting needle size before your first swatch —
they are not a substitute for swatching.
Why blocking before measuring is not optional
Most gauge errors that produce garments in the wrong size trace back to measuring
an unblocked swatch. Blocking is not a final finishing step — it is part of the
knitting process, and it belongs before you cast on.
Blocking changes gauge by more than most knitters expect
Wet-blocking wool, alpaca, or other protein fibers opens up the stitches and lets the yarn relax to its natural size. A worsted-weight swatch that measures 18 stitches per 4 inches off the needles will often measure 20 stitches per 4 inches after a wet block and dry — a difference of two full stitches. On a garment that casts on 200 stitches, that difference is 2.2 inches of finished width. Block your swatch the same way you plan to block the finished object.
Cotton and linen grow with blocking; wool and alpaca open up
Different fibers behave differently. Plant fibers (cotton, linen, bamboo) tend to grow longer and drop in row gauge when wet. Protein fibers (wool, alpaca, cashmere) tend to bloom laterally, affecting stitch gauge more than row gauge. Some synthetic blends barely change at all. This is why the blocking method matters: wet blocking causes the most dramatic change, steam blocking is gentler, and simply spritzing may produce a different result than full immersion. Match your swatch blocking to your planned finished-object care.
Measure in the center of the swatch, not the edges
The first and last few stitches on each side of a swatch curl and behave differently from the body of the fabric — tension changes at the edge because the yarn has no neighbor stitch to pull against. Similarly, the cast-on and bind-off rows often compact more tightly than the running fabric. Place your ruler or gauge tool in the center of the swatch — at least 10 stitches and 10 rows away from any edge — and count the stitches and rows that fall within a 4-inch span.
How to get the most accurate cast-on count
Four steps determine whether your finished dimensions match the schematic.
The first two happen before you touch the calculator.
Knit a swatch larger than you think you need
A 6 × 6 inch swatch gives you room to measure in the center. Anything smaller forces you to measure too close to the edges, where tension is unreliable. Knit in the stitch pattern your project uses — gauge in stockinette differs from gauge in cables, seed stitch, or ribbing.
Block the swatch exactly as you'll block the finished project
Wet block if the project will be washed. Steam block if the project will be steamed. If you never block finished objects, measure the swatch unblocked — but know that washing the finished piece later will change its dimensions. The most predictable outcome comes from matching swatch and finished-object treatment.
Count carefully over the full 4-inch span
Use a rigid ruler, not a tape measure, and count stitches you can see clearly. If you count 19.5 stitches per 4 inches, enter 19.5 — the calculator handles decimals. Rounding your swatch gauge to the nearest whole number before entering it introduces error before the calculator even runs.
Check your target dimension against the pattern schematic
For garments, the target width is usually the finished bust or hip circumference (not the body circumference while wearing — patterns specify whether ease is already included). For flat pieces like scarves or blankets, it's simply the finished dimension. Enter what the finished object should measure after blocking, not what you're aiming for mid-project.
Re-swatch if your gauge is off by more than half a stitch per inch
Half a stitch per inch sounds trivial. Across 200 stitches of a 40-inch-wide back panel it is 20 stitches — about an inch and a half of width. Go up a needle size if your fabric is too tight (too many stitches per inch), down a needle size if it is too loose (too few). Needle size on the label is only a starting point.
Where to buy
Got your numbers? Here's where to pick up what you need:
The terms that show up in gauge discussions, pattern headers, and yarn labels —
defined precisely.
Gauge
The density of knitted fabric expressed as a stitch count over a standard distance — almost always 4 inches (10 cm) in modern patterns. Gauge has two components: stitch gauge (width) and row gauge (height). It is determined by yarn weight, needle size, fiber, and individual knitter tension.
Stitch gauge
The number of stitches that span 4 inches of width in the working stitch pattern on a blocked swatch. Stitch gauge controls the finished width of your project. The calculator divides this by 4 to get stitches per inch, then multiplies by your target width.
Row gauge
The number of rows that span 4 inches of height in the working stitch pattern on a blocked swatch. Row gauge controls finished length when a pattern specifies dimensions in rows rather than inches. It is typically looser (more forgiving) than stitch gauge for patterns that measure length in inches, but critical for colorwork, raglan shaping, and other row-counted constructions.
Gauge swatch
A sample piece of knitting — typically at least 6 × 6 inches — knit on the intended needles in the intended stitch pattern and then blocked before measuring. The purpose is to determine your personal gauge before committing to the cast-on. A swatch knit on the correct needles but with a different stitch pattern than the project is unreliable.
Blocking
The process of wetting, steaming, or misting finished knitting to relax the fiber and set the stitches to their final size and shape. Blocking is not optional for accurate gauge measurement — it is the step that reveals the true gauge of your swatch. Wet blocking (soaking in water, then laying flat to dry) causes the most significant changes, especially in wool and alpaca.
Cast-on
The foundation row of loops placed on the needle before knitting begins. The cast-on stitch count determines the initial width of the piece. This calculator produces the cast-on count you need to achieve a specific finished width at your measured gauge.
Ease
The difference between a garment's finished measurement and the body measurement it is intended to fit. Positive ease means the garment is larger than the body (wearing ease or design ease). Negative ease means the garment is smaller and will stretch to fit. Patterns typically specify finished measurements including ease; enter the finished measurement from the schematic as your target width, not your body measurement, unless you're designing from scratch.
Craft Yarn Council (CYC) weight system
A standardized scale from 0 (lace) to 7 (jumbo) that categorizes yarn by thickness and corresponding typical gauge. Published by the Craft Yarn Council. The weight category appears on most yarn labels as a skein symbol with a number. It provides a starting point for needle selection — not a substitute for swatching.
Frequently asked
Gauge is the single number that translates between the abstract world of stitch counts on a pattern and the physical dimensions of finished fabric. Every pattern is written for a specific gauge. If your gauge is even one stitch per inch off from the pattern's gauge, a 200-stitch cast-on becomes the wrong width — in either direction. For a 20-inch-wide sweater front, being one stitch per inch off across 200 stitches means the finished piece is 10 inches too wide or too narrow. The calculator above converts your actual swatch gauge into the correct cast-on count for your specific dimensions.
Knit a swatch at least 6 inches wide and 6 inches tall in your project stitch pattern on the needles you plan to use. Block the swatch exactly as you plan to block the finished project — blocking changes gauge significantly for most fibers. Lay the blocked swatch flat without stretching. Measure in the center, away from edges (the first and last 10 stitches and rows behave differently). Count how many stitches and rows fall across a ruler set to 4 inches. Measure at least twice and average the counts. Enter those numbers in the calculator above.
After blocking — always. Blocking is not optional finishing; it is part of the knitting process. Natural fibers (wool, alpaca, cotton, linen) can shift gauge by 10–20% between unblocked and blocked states. A swatch that measures 20 stitches per 4 inches off the needles may measure 18 stitches per 4 inches after a wet block and dry — which changes your cast-on count by roughly 10%. Measure the swatch under the same conditions as the finished garment will experience. If it will be hand-washed and laid flat to dry, block your swatch by hand-washing and laying it flat to dry.
Gauge describes how densely your knitting packs together — it is the count of stitches across 4 inches of width (stitch gauge) and the count of rows across 4 inches of height (row gauge). Patterns express it as, for example, "20 stitches and 28 rows = 4 inches in stockinette on US 7 needles." Stitch gauge controls finished width; row gauge controls finished length. The calculator divides each by 4 to get stitches per inch and rows per inch, then multiplies by your target dimensions. Gauge is affected by yarn weight, fiber, needle size, needle material, and individual tension.
Change needle size and re-swatch. If you have too many stitches per 4 inches (your fabric is tighter than the pattern calls for), go up a needle size. If you have too few stitches per 4 inches (your fabric is looser), go down a needle size. The needle size printed on the pattern is a starting point — your gauge is what matters, not the needle size. Alternatively, use this calculator with your actual gauge to recalculate the cast-on and row counts for the finished dimensions you want, effectively creating custom stitch counts that work for your yarn and hands.
It depends on the pattern. For garments worked in pieces where length is measured in inches rather than rows, you can work until the piece measures the correct length and row gauge matters less. But for patterns that specify lengths in row counts — colorwork, cables that require a specific number of repeats, raglan shaping calculated in rows, or any pattern that says "work 80 rows" rather than "work 4 inches" — row gauge is just as critical as stitch gauge. This calculator gives you both because both can matter; check how your specific pattern measures length before deciding which number to prioritize.
Knitting patterns and the Craft Yarn Council standard both express gauge over 4 inches because measuring a larger sample reduces error. One stitch is too small a unit to measure precisely — a fractional stitch error over 1 inch becomes a significant error over 20 inches of width. Over 4 inches, you capture more stitches and the relative error of your measurement shrinks. The calculator divides by 4 internally to get stitches per inch before multiplying by your target width, so you don't have to do that step yourself. Enter the 4-inch count you count on your swatch.
The arithmetic is exact for the gauge and dimensions you enter — every formula is shown in the formulas section above. The result is only as accurate as your gauge measurements. The two biggest sources of error are measuring from an unblocked swatch and measuring too close to the swatch edges, where tension is inconsistent. Stitch counts are rounded to the nearest whole number because you cannot cast on a fraction of a stitch; this introduces at most half a stitch's worth of width difference, which is negligible on most projects.
Common mistakes with this calculator
Gauge errors are the primary reason finished knitting comes out the wrong size. These are
the mistakes that send an otherwise accurate calculator astray.
Measuring the swatch before blocking
An unblocked swatch is not the same fabric as a blocked one. Wool, alpaca, and most natural fibers relax and expand when wet-blocked, often shifting gauge by 2 or more stitches per 4 inches. Measuring fresh off the needles and entering that number will produce a cast-on count for a finished size that does not exist once the blocked fabric is worn. Always wet-block or steam-block your swatch the same way you will treat the finished object, then measure.
Measuring at the swatch edges instead of the center
The first and last few stitches of a swatch curl and compress differently from the body of the fabric. Place your ruler or gauge tool at least 10 stitches and 10 rows from any edge and measure across the interior only. Edge measurements routinely run 1–2 stitches tighter than the true body gauge and will produce a cast-on count that's too wide.
Swatching in stockinette when the pattern uses a different stitch
Gauge is stitch-pattern-specific. Cables pull in and run tighter than stockinette; seed stitch and moss stitch spread out and run looser. If your project is worked in a textured stitch, your swatch must use that exact stitch pattern. A stockinette swatch for a cabled sweater will give you a cast-on count that produces a finished garment that is too wide.
Mixing units between gauge and target dimensions
The calculator works in any consistent unit, but both inputs must use the same one. If your swatch shows 20 stitches per 4 inches and you enter a target width of 50 meaning centimeters — not 50 inches — the result will be dramatically wrong. Convert gauge and dimensions to the same unit before entering any figures.