How Nysta finds yarn substitutions

Yarn substitution is difficult because two yarns are rarely alike on more than a few parameters at once. One matches on weight but not on fibre. Another has exactly the right fibre but is spun in a completely different way. A third looks like a perfect match on the ball band but is superwash-treated, which makes it behave entirely differently in wear and wash.

To give you a useful answer, we have to weigh multiple parameters against each other simultaneously and find the yarn alternatives that work best as a whole. That is what Nysta’s yarn substitution algorithm does.

Here are the principles behind our calculations, and two concrete examples you can explore yourself.

What the algorithm is built on

Nysta’s suggestions rest on two foundations:

1. A knowledge base built from textile research, knitting literature and real-world knitting experience. We have collected and structured data from textile research and knitting books. This includes Clara Parkes (construction, spinning methods and twist), Deborah Robson (breed-specific fibre data for over 50 sheep breeds), Carol Sulcoski (substitution methods) and a study from Nature Communications (2024) on the scientific modelling of stitch topology. This theoretical knowledge is combined with practical experience from international knitting communities, the Craft Yarn Council, major producers such as DROPS and Filcolana, and Scandinavian knitting podcasts.

This is craft knowledge that has existed in knitting for decades. We’ve put it together in a form you can use directly when you’re standing with two yarns and need to know whether one can replace the other.

2. A structured yarn database. We’ve built a structured database of the yarn brands on the market, which we enrich ourselves with derived properties such as spinning method, ply construction, softness, sheen, drape, durability and pilling risk. All data goes through a thorough check for internal consistency, and we fill the gaps that producers often leave open in their specifications. When you search, all these properties are weighed against each other. If specific data is missing for a particular yarn, we calculate the score from the rest of what we know and clearly indicate how confident the match is.

The traffic light method

Each match is assigned a score from 0 to 100 along with a clear traffic light rating:

• Green: Very close match. The yarn resembles the original on the most important parameters, but you should still knit a gauge swatch.
• Yellow: There are minor differences in structure or fibre, but nothing disqualifying. You should read the specific warnings.
• Red: There are critical differences between the two yarns. It may still be possible in some cases, but you will end up with a visually or functionally different result than the pattern intends.

The traffic light is not driven solely by the overall score. A yarn alternative can technically have a high score of 85%, but still show red if it fails on a decisive parameter, for example if the fibre is unsuitable for the pattern’s prominent cable work.

Sandnes Sunday: What yarn can replace it?

Sandnes Sunday is one of the most popular yarns in Scandinavia. It is 100% merino wool in fingering weight and a classic choice for baby knits, light pullovers, cardigans and projects with silk mohair as a carry-along strand.

Below you can see the ten closest matches divided by region (Nordic, European or other). You can switch between the tabs to see the different categories:

At the top of the Nordic list you will find strong alternatives from other Nordic producers with nearly identical specifications. If you switch to the European or other brands tab, you will discover international suggestions. This makes it easy to find a good Sandnes Sunday alternative if your local yarn shop has sold out.

Knitting for Olive Heavy Merino: What alternatives are there?

Heavy Merino is Knitting for Olive’s worsted-weight yarn in 100% merino. It is widely used for chunky cable patterns, adult sweaters and warm, soft winter accessories.

Worsted-spun merino is a large international category with many well-established producers, so there are plenty of close matches across regions when looking for a Knitting for Olive alternative.

Why is good yarn substitution so hard?

There are three main reasons why finding reliable yarn alternatives on your own is difficult:

• Ball bands are often incomplete. Most manufacturers only list gauge and the overall fibre content. You can rarely see whether the yarn is an airy woolen-spun or a compact worsted-spun yarn unless you have significant hands-on experience.
• Large international databases do not help on the user side. You can look up every conceivable specification individually online, but you cannot ask these systems to automatically find the yarns that most closely resemble your starting point without manually clicking through hundreds of candidates.
• Existing calculators lack explanations. The few international substitution tools on the market often give you a raw percentage but omit the reasoning. You cannot tell whether a high score is because the fibres match perfectly, or whether it is simply the gauge that happens to be the same.

Nysta brings it together in one app. You enter the yarn you want to replace, and the app finds the closest matches, giving you a transparent, clear overview of possible yarn substitutions.

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Frequently asked questions

How does Nysta score a yarn match? Nysta evaluates multiple properties of the yarn simultaneously and weighs them into an overall score from 0 to 100. The higher the score, the closer the substitution is to the original.

What do red, yellow and green mean in Nysta’s rating? Green is a very close match. Yellow means minor differences worth knowing about. Red marks significant differences where the result is unlikely to match the original.

Can Nysta find substitutions for discontinued yarn? Yes. Nysta compares the discontinued yarn against known qualities and ranks them by how closely they match.

How does Nysta differ from other substitution tools? Nysta evaluates multiple properties simultaneously and explains why two yarns match or differ. Most other tools give a percentage without any reasoning.

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Add your yarn, and we’ll find patterns you can knit, suggest alternatives that work, or compare two yarns directly.

Sign up for launch, and we’ll let you know when the app goes live in summer 2026.