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Free Online Crochet Tool

Yarn Substitution & Yardage Calculator

Switch yarn brands without running out mid-project. Match total yardage, get the exact balls to buy, and print a shopping list — in seconds.

Yarn Substitution & Yardage Calculator — AeternaCraft Studio

Original yarn (what the pattern calls for)

Quick-fill from popular yarns

Substitute yarn (what you want to use instead)

Quick-fill from popular yarns

Shopping list

Balls to buy
4
of the substitute yarn
Total yards needed
690 yd
Safety margin
+70 yd
10.1% extra
Total weight
200 g
Total cost
$13.00

The substitute yields 3.8 yd/g vs the original's 2.3 yd/g — it is likely a thinner yarn. Your finished piece will come out smaller.

Always buy from the same dye lot — colour can shift between batches.

How to substitute yarn

  1. 1

    Read the original yarn label

    Find the yards (or metres) per ball on the original yarn's ball band. Enter the yards-per-ball and the number of balls the pattern calls for into the "Original yarn" side of the calculator.

  2. 2

    Read the substitute yarn label

    Do the same for the yarn you want to use instead. Enter its yards-per-ball, grams-per-ball, and price-per-ball (optional) into the "Substitute yarn" side.

  3. 3

    Read the balls-to-buy result

    The calculator multiplies original yards-per-ball × balls to get the total yardage, divides by the substitute's yards-per-ball, and rounds UP to a whole number. That is how many balls to buy.

  4. 4

    Check the safety margin and density warning

    If the margin is under 5%, buy one extra ball. If the calculator warns about a yards-per-gram mismatch, your substitute is a different thickness and the finished size will change.

  5. 5

    Print the shopping list and buy from one dye lot

    Click "Download Shopping List PDF" and take it to the yarn shop. Always buy all your balls from the same dye lot — colour can shift visibly between batches.

How yarn substitution really works

The single biggest mistake crocheters make when substituting yarn is comparing ball counts instead of total yardage. Two yarns can both be labelled "worsted #4" and yet have wildly different yards-per-ball: one gives you 200 yards per 100 g, another gives you 315 yards per 100 g. "3 balls" of the first is 600 yards. "3 balls" of the second is 945 yards — nearly 60% more yarn. If you swap by ball count, you will either run out or drown in leftovers.

The right formula

Always convert to total yards first, then back to balls of the substitute: 

total_yards_needed = original_yards_per_ball × original_balls
balls_to_buy = ceil(total_yards_needed / substitute_yards_per_ball)

The ceil() (round up) matters because you cannot buy 3.63 balls — you buy 4. That rounding gives you a built-in safety margin of extra yards, which the calculator reports so you know whether you can relax or whether you should buy one more ball for safety.

Why "same weight number" is not enough

The Craft Yarn Council weight system (0–7) groups yarns by typical gauge, but it does not guarantee identical thickness. A "DK #3" cotton and a "DK #3" cotton-acrylic blend can differ in yards-per-gram by 20% or more. The denser (fewer yards per gram) yarn is physically thicker, so your stitches come out larger and your finished amigurumi grows — even though the labels match.

The calculator checks this for you. If you enter grams-per-ball for both yarns, it computes yards-per-gram for each and warns you when the substitute is meaningfully thicker or thinner than the original. When that happens, pair this tool with the Amigurumi Resizing Calculator to predict the new finished size.

The dye-lot rule

Once you know how many balls to buy, buy them all at once from the same dye lot. Yarn is dyed in batches, and "colour 29" from lot A can be noticeably different from "colour 29" from lot B — especially in reds, blues, and darks. Mixing dye lots in a single amigurumi is the most common cause of a visible colour seam. If you must buy across lots, work two rows from one ball, then two from the other, alternating throughout to blend the difference.

Worked example

A pattern calls for 3 balls of YarnArt Jeans (175 yd / 50 g per ball). You want to use Hobbii Rainbow Cotton 8/4 (186 yd / 50 g per ball) instead. Total yards needed = 175 × 3 = 525 yd. Balls to buy = ceil(525 / 186) = ceil(2.82) = 3 balls. Safety margin = (3 × 186) − 525 = 33 yd, about 6.3% — comfortable, but buy a 4th ball if you tend to crochet loosely. Yards-per-gram are nearly identical (3.5 vs 3.72), so the finished size will match the original.

Common Yarn Weights: Grams to Yards Matrix

Typical yardage per 50 g and 100 g ball by CYC weight and fibre. Cotton is denser than acrylic or wool, so the same gram weight yields fewer yards. Always check the ball band of your actual yarn — these are starting estimates, not absolutes.

CYC Level Weight Name Fibre Yards per 50 g Yards per 100 g
0 Lace Cotton ~220 yd ~440 yd
0 Lace Acrylic ~250 yd ~500 yd
0 Lace Wool ~275 yd ~550 yd
1 Fingering Cotton ~165 yd ~330 yd
1 Fingering Acrylic ~190 yd ~380 yd
1 Fingering Wool ~210 yd ~420 yd
2 Sport Cotton ~140 yd ~280 yd
2 Sport Acrylic ~160 yd ~320 yd
2 Sport Wool ~175 yd ~350 yd
3 DK Cotton ~115 yd ~230 yd
3 DK Acrylic ~130 yd ~260 yd
3 DK Wool ~140 yd ~280 yd
4 Worsted Cotton ~90 yd ~180 yd
4 Worsted Acrylic ~105 yd ~210 yd
4 Worsted Wool ~115 yd ~230 yd
5 Bulky Cotton ~65 yd ~130 yd
5 Bulky Acrylic ~75 yd ~150 yd
5 Bulky Wool ~82 yd ~165 yd
6 Super Bulky Cotton ~45 yd ~90 yd
6 Super Bulky Acrylic ~52 yd ~105 yd
6 Super Bulky Wool ~58 yd ~115 yd

To convert your own skein: yards per gram = total yards ÷ total grams. Multiply by the grams your project needs to estimate total yardage.

Amigurumi Sphere Sizing Chart

How many stitches per round an amigurumi sphere needs at a given finished diameter. Every row increases by 6 stitches per round (the classic amigurumi rule): circumference stitches ≈ π × diameter × gauge. Sizes shown use a typical worsted/DK single-crochet gauge of ~4.8 stitches per inch.

Finished Diameter Stitches in Final Round Increase Rounds Straight Rounds (approx.)
1.2 in / 3 cm 18 st 3 rounds 2 rounds
1.6 in / 4 cm 24 st 4 rounds 3 rounds
2.0 in / 5 cm 30 st 5 rounds 4 rounds
2.4 in / 6 cm 36 st 6 rounds 5 rounds
2.8 in / 7 cm 42 st 7 rounds 6 rounds
3.2 in / 8 cm 48 st 8 rounds 7 rounds
3.6 in / 9 cm 54 st 9 rounds 8 rounds
4.0 in / 10 cm 60 st 10 rounds 9 rounds
4.4 in / 11 cm 66 st 11 rounds 10 rounds
4.8 in / 12 cm 72 st 12 rounds 11 rounds
5.2 in / 13 cm 78 st 13 rounds 12 rounds
5.6 in / 14 cm 84 st 14 rounds 13 rounds

Decrease rounds mirror the increases in reverse order to close the sphere. Adjust straight rounds to control the shape: more straight rounds = longer (egg-shaped) pieces, fewer = rounder and plumper.

Crochet Hook Size Conversion Chart

Metric (mm) to US designations, plus the recommended hook range for each yarn weight. Use this as a starting point — your personal tension always decides the final gauge.

Metric US Metric US
2.0 mm B-1 4.5 mm 7
2.3 mm B-1 5.0 mm H-8
2.5 mm C-2 5.5 mm I-9
2.8 mm C-2 6.0 mm J-10
3.0 mm D-3 6.5 mm K-10½
3.3 mm D-3 7.0 mm L-11
3.5 mm E-4 8.0 mm M-13
3.8 mm F-5 9.0 mm N-15
4.0 mm G-6 10.0 mm P/Q
4.5 mm 7 15.0 mm Q
5.0 mm H-8 5.0 mm H-8
5.5 mm I-9 5.5 mm I-9
6.0 mm J-10 6.0 mm J-10
6.5 mm K-10½ 6.5 mm K-10½
7.0 mm L-11 7.0 mm L-11
8.0 mm M-13 8.0 mm M-13
9.0 mm N-15 9.0 mm N-15
10.0 mm P/Q 10.0 mm P/Q
15.0 mm Q 15.0 mm Q

Yarn Weight → Recommended Hook

CYC Level Weight Name UK / AU Hook Range Typical SC Gauge
0 Lace 1 ply 1.5–2.3 mm 36–42 st / 10 cm
1 Super Fine / Fingering 4 ply 2.3–3.5 mm 32–36 st / 10 cm
2 Fine / Sport 5 ply 3.5–4.5 mm 28–32 st / 10 cm
3 Light / DK DK / 8 ply 4.5–5.5 mm 24–28 st / 10 cm
4 Medium / Worsted Aran 5.5–6.5 mm 20–24 st / 10 cm
5 Bulky / Chunky Chunky 6.5–9.0 mm 16–20 st / 10 cm
6 Super Bulky Super Chunky 9.0–15.0 mm 12–16 st / 10 cm
7 Jumbo Super Chunky+ 15.0–25.0 mm 8–12 st / 10 cm

Frequently asked questions

How do I substitute one yarn for another in a crochet pattern?

Never compare ball counts — compare total yardage. Multiply the original yarn's yards-per-ball by the number of balls to get total yards needed, then divide by the substitute's yards-per-ball and round UP. For example, 3 balls of a 230-yard yarn (690 yards total) divided by a 190-yard substitute = 3.63, so buy 4 balls. Always buy a little extra from the same dye lot.

Why does my finished piece come out a different size when I substitute yarn?

Because two yarns with the same CYC weight number can have different yards-per-gram densities. If your substitute yields fewer yards per gram, it is physically thicker, so your stitches will be larger and the finished amigurumi will come out bigger — even if the ball says "worsted #4" like the original. Check yards-per-gram of both yarns: if they differ by more than about 15%, expect a size change and use the Amigurumi Resizing Calculator to predict it.

How many extra balls should I buy when substituting yarn?

After matching total yardage and rounding up to whole balls, buy one extra ball if your safety margin is under 5–10%. Gauge swatching, colour changes, and tension differences can easily consume a 5% margin. If the margin is over 60%, check whether a larger skein is available to reduce leftovers.

Is this yarn substitution calculator free?

Yes, the calculator is free, requires no signup, and exports a printable PDF shopping list. It runs entirely in your browser and there is no usage limit.

See Your Yarn Choice as a Visual Grid

Know your yarn — now visualise the pattern.

Upload a photo to AeternaCraft Studio, pick your substituted yarn colours, and get a colour-matched grid with row-by-row instructions — complete with the exact yarn you just calculated.

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