Fiber Blend Ratio Calculator
Blending percentages for target yarn properties.
About this calculator
This calculator turns rough blend percentages for up to three fibers into exact weights you can measure on a scale, and predicts how soft the resulting yarn will feel. Whatever percentages you enter for fiber 1, 2, and 3 are first normalized so they sum to exactly 100% — so entering 70/30 or 7/3 produces the same blend, and setting fiber 3 to zero collapses it to a clean two-fiber blend. Those normalized percentages are then applied to your total batch weight (in ounces) to get the exact weight of each fiber to pull and combine, whether on hand cards, a drum carder, or by commercial blending.
The predicted softness comes from a weighted average of each fiber's micron count (fiber diameter) — finer fibers like silk (roughly 10-14 microns) pull the blend average down, while coarser fibers like alpaca (20-30 microns) pull it up — and that blended micron is mapped to a 1-10 softness rating, with anything under 15 microns scoring a 10 and anything above 36 microns scoring a 3. This is a linear approximation: real next-to-skin comfort also depends on fiber crimp, scale structure, and how evenly the fibers are actually distributed during carding, not just the average diameter, so two blends with the same blended-micron number can still feel different against skin. Use the weight breakdown to portion fiber accurately, and the softness rating as a directional guide rather than a guarantee.
Inputs
Results
Fiber 1 (normalized %)
70%
How to Use This Calculator
- Enter the percentage and micron count for each fiber in the blend (merino ~21 µm, alpaca ~25 µm, silk ~12 µm).
- Set fiber 3 percentage to 0 if you are blending only two fibers.
- Enter the total batch weight in ounces.
- Read the normalized percentages to see the actual proportions after auto-normalization to 100%.
- Use the weight outputs in ounces for each fiber to measure on a scale before blending.
- Check the blended micron output to predict the softness of the finished yarn.
How the result changes with Fiber 1 (%)
| Fiber 1 (%) | Fiber 1 (normalized %) |
|---|---|
| 35 | 53.8% |
| 53 | 63.9% |
| 100 | 76.9% |
What each input means
- Fiber 1 (%)
- Percentage of fiber 1 (e.g. merino). Ratios auto-normalize to 100%.
- Fiber 1 micron
- Average fiber diameter in microns. Merino 17-22, alpaca 20-30, silk 10-14.
- Fiber 2 (%)
- Percentage of fiber 2 (e.g. silk).
- Fiber 2 micron
- Average fiber diameter in microns for fiber 2.
- Fiber 3 (%)
- Percentage of fiber 3 (set to 0 if not used).
- Fiber 3 micron
- Average fiber diameter in microns for fiber 3.
- Total batch (oz)
- Total weight of the blended batch in ounces.
What each result means
- Fiber 1 (normalized %)
- Normalized percentage of fiber 1.
- Fiber 2 (normalized %)
- Normalized percentage of fiber 2.
- Fiber 3 (normalized %)
- Normalized percentage of fiber 3.
- Fiber 1 weight (oz)
- Weight of fiber 1 needed.
- Fiber 2 weight (oz)
- Weight of fiber 2 needed.
- Fiber 3 weight (oz)
- Weight of fiber 3 needed.
- Blended micron
- Weighted average fiber diameter of the blend.
- Softness rating (1-10)
- Estimated softness: 10 = ultra-fine, 7 = fine, 5 = medium, 3 = coarse.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersFiber 1 (%) = 70, Fiber 1 micron = 21, Fiber 2 (%) = 30, Fiber 2 micron = 12 = 7 input(s) provided
- Calculate Fiber 1Fiber 1 = fiber1Pct * norm70 = 70%
- Calculate Fiber 2Fiber 2 = fiber2Pct * norm30 = 30%
- Calculate Fiber 3Fiber 3 = fiber3Pct * norm0 = 0%
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What happens if my fiber percentages don't add up to 100%?
The calculator normalizes whatever you enter so the three percentages always sum to exactly 100% before computing weights and blended micron. That means entering 7/3 produces the same result as entering 70/30 — only the ratio between the numbers matters, not their raw sum.
Can I use this to blend just two fibers instead of three?
Yes — set fiber 3's percentage to 0. Since it's included in the normalization sum, a zero value for fiber 3 simply drops out and the remaining two percentages are normalized against each other, giving you a clean two-fiber blend.
How exactly is the softness rating calculated from micron counts?
The calculator takes a weighted average of each fiber's micron count using the normalized blend percentages, producing a single "blended micron" figure. That number is then mapped to a 1-10 scale in fixed bands — under 15 microns scores a 10, while anything above 36 microns scores a 3 — so a small amount of a very fine fiber like silk can still meaningfully soften a coarser main fiber.
Why might two blends with the same blended-micron number still feel different against skin?
The blended micron is a simple weighted average of fiber diameter and doesn't account for fiber crimp, scale structure, or how evenly the fibers are actually distributed during carding. Two blends that land on the same average diameter can still have different real-world hand feel depending on these factors.
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