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How to Substitute Yarn in a Pattern
Complete step-by-step guide to substituting yarn without ruining the result
Short answer: To substitute yarn in a pattern, you must find a yarn with similar yardage, calculate how many skeins you need, and knit a swatch to check the gauge. Yardage is more important than weight!
Why do you want to substitute yarn?
There are many good reasons to substitute yarn in a pattern. Maybe the original yarn is unavailable, or you've found a yarn on sale that you'd like to use. Some people have allergies to wool and need to find alternatives, while others want a different color or quality than what the pattern suggests.
Whatever the reason, it's perfectly possible to substitute yarn - as long as you follow some key principles. In this guide, you'll learn everything you need to know to succeed with yarn substitution. Feel free to use our yarn calculator once you've found your yarn.
Step 1: Understand Yardage
Yardage is the single most important concept when substituting yarn. It tells you how many meters or yards of yarn you get in a skein or per 100 grams. You can find this on the yarn label.
Example of Yardage:
- Thin yarn: 400 meters per 100g (e.g., fingering/sock)
- Medium yarn: 200 meters per 100g (e.g., DK/sport)
- Thick yarn: 100 meters per 100g (e.g., chunky)
Two yarns can weigh the same but have completely different yardage. A thin yarn has more yardage than a thick yarn at the same weight. Therefore, it's the yardage - not the weight - that determines how much yarn you need.
Step 2: Calculate How Much Yarn You Need
Once you've found an alternative yarn with similar yardage, you must calculate how many skeins you need. Here's the formula:
Number of new skeins = (Original yardage × Number of skeins) ÷ New yarn's yardage
Practical Example:
The pattern requires 5 skeins of 50g with 175 meters per skein. You want to use a yarn with 200 meters per skein.
Total yardage: 5 × 175m = 875m
New skeins: 875m ÷ 200m = 4.375 ≈ 5 skeins
Tip: Always round up! It's better to have a little too much than too little yarn.
Want to skip the math? Use our yarn substitution calculator which does the job for you in seconds.
Step 3: Check Yarn Weight and Fiber Content
Even if the yardage is similar, you should also consider the yarn weight category and the fiber content. This affects how the finished garment looks and behaves.
Yarn Weight
Yarn is often categorized into weights like lace, fingering, sport, DK, worsted, chunky, etc. Even if two yarns have the same yardage, they may be in different weight categories. For the best result, choose yarn in the same category.
Fiber Content
Different fibers behave differently:
- Wool: Elastic, warm, forgives gauge errors
- Cotton: Less elastic, can "sag", good for warm weather
- Alpaca: Very warm, can become heavy, minimal elasticity
- Acrylic: Affordable, allergy-friendly, less breathable
- Blends: Combine properties from multiple fibers
Important: If you switch from wool to cotton or vice-versa, the garment may behave differently than expected. Cotton stretches more in length, while wool is more elastic.
Step 4: Knit a Swatch
This is the most important step - and the one many people skip! Even if you use yarn with the same yardage, your personal gauge can vary with different yarn types.
How to make a swatch:
- Cast on 30-40 stitches with the new yarn
- Knit 12-15 cm in the same pattern as the instructions
- Wash and block the swatch (important!)
- Measure how many stitches and rows you get per 10 cm
- Compare with the pattern's gauge
If you have too many stitches per 10 cm, you're knitting too tightly - switch to thicker needles. If you have too few stitches, you're knitting too loosely - switch to thinner needles.
Use our gauge calculator to get needle size recommendations.
Step 5: Consider Project Type
Some projects are more sensitive to yarn substitution than others:
Easy to substitute yarn in:
- Scarves and shawls (size is not critical)
- Blankets and pillows (can be adjusted)
- Simple sweaters in stockinette stitch
Harder to substitute yarn in:
- Fair Isle and intarsia (color shifts may look different)
- Lace (drape may change)
- Socks (durability is important)
- Garments with specific fit requirements
Common Mistakes in Yarn Substitution
Mistake 1: Using weight instead of yardage
"The pattern uses 500g of yarn, so I'll buy 500g of a different yarn." This only works if both yarns have the same yardage!
Mistake 2: Skipping the swatch
Even professional knitters knit a swatch. It takes 30 minutes but can save you many hours of work if the gauge doesn't match.
Mistake 3: Not buying enough yarn
Always buy a little extra! Dye lots can change, and it's frustrating to run out of yarn in the middle of a project.
Yarn Substitution Checklist
- Checked yardage of the original yarn
- Found yarn with similar yardage
- Calculated number of skeins (with a little extra)
- Considered yarn weight and fiber content
- Knitted and washed a swatch
- Measured gauge and adjusted needle size
- Bought enough yarn from the same dye lot
Useful Tools for Yarn Substitution
We've created several calculators to make yarn substitution easier:
Yarn Substitution Calculator
Calculate how many skeins you need of the new yarn
Yardage Calculator
Convert between grams and meters/yards
Gauge Calculator
Get needle size recommendations
Conclusion
Substituting yarn in a pattern is perfectly possible when you follow the right principles. Remember that yardage is more important than weight, and that a swatch is always worth the time. With proper preparation, you can safely use the yarn you want - and get a successful result!
Can I always substitute yarn in a pattern?
Yes, you can substitute yarn in most patterns, but you must ensure the new yarn has similar yardage and gauge as the original. Some patterns are more sensitive to yarn substitution than others - especially those with complex patterns or specific drape requirements.
What is most important when substituting yarn - weight or yardage?
Yardage is the most important! Two yarns can weigh the same but have completely different yardage. Always use yardage (meters/yards per skein or per 100g) as the basis for your calculation, not weight.
How do I know if the yarn is suitable for the pattern?
Check three things: 1) Yardage should be similar, 2) Gauge must match (knit a swatch!), 3) Yarn weight category and fiber content should be similar for the best result.
Do I have to knit a swatch when substituting yarn?
Yes, absolutely! Even if you use yarn with the same yardage, different yarn types can result in different gauge. A swatch ensures that the finished garment will be the correct size.
Can I substitute wool with cotton?
Yes, but be aware that cotton and wool behave very differently. Cotton has less elasticity and can become heavier when washed. Cotton garments can also 'sag' more than wool. Consider if this is appropriate for your project.