GE profit calculator
Net profit on a Grand Exchange flip, after the 2% sale tax.
Your trade
What you pay per item. Accepts 10k, 2.5m, 1b.
What you sell for, before tax.
Usually your buy limit, or as much as you can afford.
Result
Buying 1,000 at 1,000 and selling at 1,100 leaves 78,000 gp after tax, from 1,000,000 gp of capital.
How the maths works
A flip has three moving parts: what you pay, what you sell for, and what the Grand Exchange takes in between. The last one is the part people forget, and on thin margins it is the difference between a profit and a loss.
The calculation runs in this order:
- Tax per item is 2% of the sale price, rounded down. It is charged per item, not on the total, which is why a large quantity of cheap items is taxed slightly less than 2% overall.
- Net sale price is the sale price minus that tax. This is what actually arrives in your bank.
- Margin is the net sale price minus your buy price. If this is negative, the trade loses money however good the raw spread looked.
- Net profit is the margin multiplied by quantity.
- ROI is net profit divided by the capital committed. This is the number to compare across items, because a 500 GP margin means something very different on a 2,000 GP item than on a 2,000,000 GP one.
Why ROI matters more than margin
Two items can offer the same margin and be completely different trades. A 1,000 GP margin on an item costing 5,000 GP returns 20% on capital. The same 1,000 GP margin on an item costing 500,000 GP returns 0.2%. With a fixed bank and eight offer slots, the first item will out-earn the second many times over.
The exception is when buy limits bite. A high-ROI item with a limit of 100 units caps what you can earn per four-hour cycle regardless of how good the percentage looks. That is why our flipping guide ranks by profit per buy limit rather than by margin or ROI alone.
What this calculator does not account for
It assumes both sides of your trade fill at the prices you entered. In practice, offers placed at the very edge of the spread often sit unfilled while the market moves, and the price you eventually get is worse than the one you planned around. Checking an item’s trading volume before committing is the single best defence against that.
Worth knowing
Prices move. A margin that exists when you place an offer may not exist when it fills.
The tax is capped at 5,000,000 GP per item, so very expensive items are taxed at an effective rate below 2%.
Items sold below 50 GP are not taxed at all.