Brew Thai tea in bulk at 70 g of mix per litre of water for café strength — the same ratio as a single glass, just in a bigger vessel. Published café recipes run from about 50 g to 85 g a litre, so treat 70 g as the place to start and taste from there. A 20 L urn takes 1400 g of loose mix at that strength and yields about 83 glasses, with roughly $17.78 of tea in it.
The ratio is the easy part and it scales cleanly. Everything around it doesn't. What separates cup fifty from cup one is when you pull the leaf, whether the milk went into the batch, and how you strained it — and those are the failures we've counted rather than guessed at.
The batch table
Water, mix at each strength, yield and cost. Glasses assume 240 ml of brewed tea per serve, before milk and ice — which is why a glass leaves the pass considerably bigger than that. Cost is quoted at Standard.
| Water | Light 50 g/L | Standard 70 g/L | Strong 85 g/L | Glasses | Tea cost |
|---|---|---|---|---|---|
| 2 L | 100 g | 140 g | 170 g | 8 | $1.78 |
| 4 L | 200 g | 280 g | 340 g | 16 | $3.56 |
| 6 L | 300 g | 420 g | 510 g | 25 | $5.33 |
| 8 L | 400 g | 560 g | 680 g | 33 | $7.11 |
| 12 L | 600 g | 840 g | 1020 g | 50 | $10.67 |
| 20 L | 1000 g | 1400 g | 1700 g | 83 | $17.78 |
Tea only. Condensed milk, evaporated milk, sugar, ice and the cup are your own line items, and together they cost several times more than the tea does. Cost is at the cheapest published case price on our wholesale page, read 2026-08-30.
Brewing stronger is a legitimate choice and it's cheap. Moving from 70 g to 85 g a litre adds about five cents to a glass. If your drink is fighting a lot of ice or a sweet milk, that is the first dial to turn — not a different brand. Our own home recipe sits below the light end of this band, which is fine at a kitchen table and too weak behind a bar.
The method, and where batch differs from a single glass
- Boil the water properly, then brew. Thai tea is a coarse black blend and it needs genuinely boiling water. Water that's merely hot is one of the counted failure modes, and at batch size it's easy to hit: a big vessel of just-off-the-boil water drops below temperature fast.
- Steep, then get the leaf out. Five minutes or so, then remove it. This is the single biggest difference from home brewing — see below.
- Sweeten while it's hot, if you sweeten the batch at all. Sugar dissolves in hot tea and won't in cold. The trade-off is that you've now fixed the sweetness for every drink out of that urn.
- Cool it before it goes in the fridge, not after. Chilling a hot batch too fast clouds it. Let it come down first, then refrigerate.
- Add milk per glass, never to the batch. The most important line on this page, and the reason is below.
Pull the leaf. This is the batch-specific killer.
At home the tea leaves the pot when you pour it, five minutes after it went in. In a 20-litre urn, leaf left in the vessel keeps extracting for hours, and it doesn't get stronger — it gets astringent and bitter. Over-steeping is one of the most frequently blamed causes in our data, and batch brewing is the setting where it happens by default rather than by mistake.
Which is why service-quality Thai tea is a two-vessel job: brew in one, strain into another, hold in the second. If your batch tastes fine at 9am and harsh by lunch and nothing else changed, this is why.
Straining is an equipment problem at volume
Thai tea mix is cut very fine — far finer than most loose black tea — and a lot of people discover their strainer doesn't hold it. A home sieve that just about copes with a pot will not cope with 20 litres poured at speed, and gritty sediment in the bottom of a glass is a complaint you'll hear about. Use a proper cloth filter or a fine mesh brew basket sized for the vessel, and budget for it as equipment rather than improvising.
Keep the milk out of the batch
It is tempting: pre-mix the whole thing, pour one liquid, serve faster. Don't. Three reasons, and the first is the one that matters.
- A dairy batch is a different food-safety problem from a tea batch. Holding times and temperatures for a milk-containing beverage are stricter, and they're set by your local health code, not by us. Check yours before you consider it.
- You lose the drink. The layered pour — dark tea, then the milk falling through it — is most of why the drink photographs the way it does. Pre-mixed, it arrives as one flat colour.
- You lose every adjustment. Less sweet, extra milk, dairy-free — all of it is impossible once it's in the urn. Those are orders you can otherwise take.
Brew the tea, sweeten it, hold it. Milk goes in the glass.
What people actually blame, counted
We read a corpus of public discussions about Thai tea that came out wrong and coded every complaint to its source. This is the full tally — the same failures a café hits, except a café hits them a batch at a time.
| What went wrong | Times said | Discussions |
|---|---|---|
| not enough sweetened condensed milk (or creamer used instead) | 7 | 4 |
| instant or 3-in-1 powder instead of leaf | 6 | 4 |
| not enough sugar | 6 | 3 |
| over-steeped into bitterness and astringency | 6 | 4 |
| too little leaf for the water | 5 | 4 |
| water not hot enough / not boiled with the leaves | 4 | 3 |
| no way to strain leaf that fine | 3 | 3 |
| tea never pulled/aerated | 1 | 1 |
Read the top of that list as a shop rather than as a cook. The milk and the sugar are portioning problems, which is a training and a jigger problem, not a recipe one. Over-steeping and under-dosing are timer and scale problems. Only one line on the entire list is solved by changing what you buy — using an instant powder instead of leaf — and that one is a decision you already made.
The sourced quotes behind every row are on our consensus dataset, with dates and links.
What this costs you to run
At the cheapest published case price, the tea in a glass runs about 21.3¢ at standard strength (15.2¢–25.9¢ across the band). Against a $5–7 menu price that is roughly 4%, which is worth sitting with: one dumped batch costs more than a week of savings from a cheaper supplier. Buy on consistency and reliability, then on price. Case pricing, minimums and lead times across six sourcing routes are on our Thai tea wholesale page.
Tell us what you're buying and we'll point you at the right route
Free, and there's nothing to sign up for. We'll reply with the routes that fit your volume — and if one of the suppliers above is the obvious answer, we'll introduce you. We don't sell tea, so we've got no reason to steer you anywhere in particular.
Common questions
How much Thai tea mix per litre?
About 70 g per litre of water for café strength, with published recipes running 50 g to 85 g. A batch of 8 L takes 560 g at standard strength and yields around 33 glasses.
How long does batch Thai tea last?
Unsweetened, strained, refrigerated and with no dairy in it, brewed Thai tea holds its quality for a few days — it's typically flavour, not spoilage, that ends it. Once milk is in it, that changes completely, and holding times for a dairy beverage are set by your local health code. That is the single strongest reason to keep milk out of the batch.
Why does my batch taste bitter later in the day?
Almost always because the leaf is still in it. Tea left in the vessel keeps extracting long past the point where it's adding anything good, and bitterness and astringency are what it adds instead. Strain into a second vessel as soon as the steep is done.
Should I add condensed milk to the whole batch?
No. It creates a stricter food-safety category than plain tea, it removes the layered pour customers expect, and it makes every "less sweet" or "dairy-free" order impossible. Sweeten the batch if you like; add the milk in the glass.
Can I use instant Thai tea powder for a shop?
You can, and it's faster. It's also the one item on our counted failure list that's solved purely by what you buy — instant powder is built on non-dairy creamer and tastes flat next to brewed leaf. If your drink is the reason people come, brew it.