Where to buy lye for soap making
Lye is a restricted product in a lot of places, which is why finding it is harder than it should be. Here is where to look and what to check.
Buy sodium hydroxide from a dedicated soap supplier wherever you can — they sell 99% beads in a resealable tub, which is what actually matters. Chemical suppliers are cheaper at volume, and food-grade pickling lye is chemically identical. Avoid hardware-store drain cleaner entirely. A 2 lb tub covers roughly 6 one-kilogram batches.
Nobody searches for where to buy flour. Lye gets asked about constantly because it is genuinely awkward to get: in many countries it is a controlled precursor chemical, it cannot travel by air, and a lot of general retailers simply will not carry it. That is not a conspiracy against soapers — it is the same regulation that makes it a nuisance to ship anything caustic.
The practical effect is that the cheapest listing you find is often the worst purchase. Shipping surcharges, quantity limits and a supplier who is out of stock for two months all cost more than the few pounds saved. And the substitute sitting on a hardware shelf — drain cleaner — is the one option that can genuinely ruin a batch, because what else is in the bottle is frequently not on the label.
Before you order, work out what you actually need. A one-kilogram batch of a standard beginner blend takes about 143 g of sodium hydroxide, so a 2 lb tub is roughly 6 batches and a 1 kg tub about 7. Run your own recipe through the lye calculator first — a coconut-heavy blend needs noticeably more.
Where to look
Ranked by how well each actually serves a small-batch soaper. We do not list named shops or prices — stock and shipping terms change constantly, and a stale recommendation is worse than none.
How much to order
The right first order. Enough to learn on, and it will be used before the tub has been open long enough to matter.
The common metric size. Much the same purchase, and the one most European suppliers stock.
Only once you know your batch size. Opened lye pulls water from the air, so buying ahead has a real cost.
Why it is hard to find
Sodium hydroxide has uses well beyond soap, and several jurisdictions restrict its sale, require ID, or cap the quantity an individual can buy. Rules differ by country and change — check your own before assuming a supplier can ship to you.
Caustics are ground-only freight almost everywhere. That means slower delivery, a hazmat or dangerous-goods surcharge on many carriers, and some sellers refusing to ship it at all beyond their own country.
A supermarket carries no lye for the same reason it carries no concentrated acid. Soap suppliers do because their customers need it and they are set up to package and ship it properly.
Lye draws water out of the air. A tub that reseals properly stays accurate for years; a bag with a fold-over top gains weight, and every batch you weigh from it afterwards is quietly short of lye.
Small suppliers run out. A seller who reliably has it beats one that is cheaper twice a year, especially if you are selling and cannot simply skip a month.
Before you order
You want 99% or higher, printed on the product or its data sheet. A calculator assumes pure lye — at 96% you are under-dosing by four per cent and will spend a week wondering why the bars are soft.
Some drain products are largely sodium hydroxide. They also routinely contain aluminium shavings, chelators or surfactants that the label does not disclose, and aluminium reacts with lye. You cannot calculate a recipe against an unknown.
Sealed goggles, chemical-resistant gloves, and a dedicated stainless or HDPE jug. Improvising these on the day the lye arrives is how people get hurt.
A scale reading to 0.1 g matters more than which supplier you chose. Lye measured by volume rather than weight is the single most dangerous shortcut in soap making.
Sealed lye keeps for years; opened lye starts absorbing moisture immediately. Buying five pounds to save on shipping is a false economy if it takes you two years to use it.
Work out how much you need
Enter your oils and superfat to see the lye weight for a batch, so you know what a tub actually buys you.
Open the lye calculator →Print the safety checklist
Lye handling, kit and the order of operations, on one page you can pin up where you work. Free.
Estimates, not advice. Every figure on this page is computed from published reference values and standard measures, so your own inputs, equipment and conditions will move it. Nothing here is professional advice — talk to a qualified professional before acting on it.