Potions trade at different prices depending on how many doses are in the vial — and those prices are rarely perfectly proportional. That gap is the entire opportunity behind decanting.

The idea in one line

Buy the dose that is cheapest per dose, decant it to the dose that sells highest per dose, and pocket the difference. Decanting at Bob Barter in the Grand Exchange is free and conserves total doses, so it is close to pure arbitrage.

Always compare price per dose, not the sticker price. A 4-dose potion at four times the price of a 1-dose is break-even; you want the ones that are out of line.

Watch out for

  • The 2% sell tax on the side you sell — factor it in before celebrating a margin.
  • Volume: some dose tiers barely trade, so your offers may sit unfilled.

Which potions are worth decanting

Not every potion family is equally worth the effort. The best candidates are ones with steady, ongoing demand — combat and skilling potions people burn through constantly, like prayer or stat-boosting potions — since consistent demand means both sides of the trade actually fill. Niche potions used by a small fraction of players might show an appealing price gap between doses, but if barely anyone is buying the 4-dose or selling the 1-dose, that gap is theoretical; your offers can sit for a long time before either side completes.

The Bob Barter fee and travel time

Decanting itself is free at Bob Barter in the Grand Exchange, but getting there and back, along with banking trips to restock materials, is a real time cost that doesn't show up in the raw profit-per-dose math. A decanting flip that looks excellent per dose can still be a mediocre use of an hour once you account for how much of that hour is spent walking and banking rather than actually decanting. It's worth batching large quantities per trip specifically to spread that fixed travel cost across as many doses as possible.

Buying in bulk before a decanting session

Rather than buying a few potions, decanting them, then going back to buy more, it's generally more efficient to buy your entire planned quantity upfront in one purchasing pass, then run the whole decanting batch in one uninterrupted session. This reduces the number of separate banking trips and keeps your attention focused on one task at a time, rather than constantly switching between buying and decanting, which tends to slow the whole process down more than it might seem.

Why the dose gap exists in the first place

The price gap between dose tiers exists mainly because different players want different things — someone buying for immediate personal use often wants a 4-dose potion for convenience, while someone stocking up in bulk, or another flipper, might prefer the 1-dose form for exactly this kind of arbitrage. That difference in what buyers actually want, rather than any intrinsic difference in the potion itself, is what keeps the per-dose prices from perfectly lining up — and it's also why the gap tends to persist over time rather than fully correcting itself the way a true market inefficiency eventually would.

Keeping a simple mental model

Rather than memorizing exact numbers for every potion family, it helps to keep one simple mental model: multiply the 1-dose price by four and compare it to the actual 4-dose price. Whichever direction that comparison favors tells you which way to decant, in general terms, even before you check the exact numbers. It's not a substitute for checking real prices, but it's a fast sanity check for whether a given potion family is even worth investigating further today.

The tracker's Decanting tab does the per-dose maths for every potion family automatically, net of tax, and ranks them by profit per dose.

One more practical detail: always double-check that the potion family you're decanting still has real buyers on both ends before committing a large batch — a great per-dose margin on paper is worthless if the dose tier you're left holding afterward has almost no demand to sell into.