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Soap Lye Calculator (NaOH / KOH)

Build a multi-oil soap recipe and get the exact NaOH, KOH or dual-lye and water, with superfat, editable SAP values and the full safety brief.

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Soap Lye Calculator (NaOH / KOH) works straight from this page — free, instant, nothing to install. You will find it under Crafts & making, with Beading Pattern Calculator and Candle Wax Calculator for the neighbouring cases.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Soap Lye Calculator (NaOH / KOH) do?

Build a multi-oil soap recipe and get the exact NaOH, KOH or dual-lye and water, with superfat, editable SAP values and the full safety brief.

When would I actually use this?

Buying the right amount before starting: how many skeins a jumper needs, how much wax fills the moulds you own, how much resin a bezel takes, how much fabric a quilt binding eats.

What is the most common mistake?

Sizing from the pattern's yarn rather than your own. Two yarns sold as the same weight can differ by a fifth in metres per hundred grams, and a hook or needle size converted between systems is a nominal diameter, not a promise about gauge — knit a swatch.

Is there a tool for the next step?

Candle Wax Calculator is the closest one after this: Turn a container's volume into the wax weight and fragrance oil you actually need, for soy, paraffin, coconut, beeswax, palm or a blend — in oz, grams and pounds.

What else is worth having open alongside it?

Crochet Hook Size Converter and Cross-Stitch Floss Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Hook and needle equivalences follow the Craft Yarn Council's metric table; the soap calculator uses published saponification values, which vary by oil batch, so the lye figure is a starting point that a superfat margin is meant to absorb.

Further reading

All guides →
How-toEstimating Embroidery Thread From a Stitch CountThirty thousand stitches at 3.5 mm with fifteen per cent waste is 120.7 metres. The stitch count comes from the file; the average length is an assumption, and doubling it doubles the answer.How-toCast On From Your Gauge, Not From the PatternTwo stitches per 10 cm is the difference between a 50 cm scarf and a 55 cm one. The pattern's cast-on number is only correct for the person who wrote it.ComparisonUS 8, UK 6, 5 mm: Three Needle Scales That Never AgreeThe American numbers count up as the needle gets fatter and the British ones count down. They cross exactly once, at 4.5 mm, where both read 7 — and that single coincidence is the trap.ExplainerThe Aida Count Sets the Size, Not the ChartThe same 100 × 120 chart finishes 23 cm wide on 11-count and 11.5 cm wide on 22-count — twice the width, four times the area, from one number on the fabric label.ExplainerYarn in Metres, Yarn in Grams, and the Ball Band Between ThemA pattern asks for length and a shop sells weight. 400 yards of DK is 182 g and two balls; 400 yards of fingering is 100 g and one. The bridge is a single number on the label, and reading it wrong is the reason projects run out.ExplainerThe Flat Pattern of a Cone Is a Sector, Not a CircleRoll a 50 mm cone 80 mm tall and its pattern is a 190.8° slice of a 94 mm circle. Flatten a nearly cylindrical lampshade and the pattern radius runs to 839 mm — the shallower the taper, the further away the apex.