Why does my price come out at two and a half times cost with 30% fees and a 30% margin?

Where 125 comes from

Picture the price as a hundred parts. The platform takes 30, and you want 30 as profit. Only 40 parts remain, and they have to pay for the whole product. If the cost is 50, each part is worth 1.25 and the full price is 125.

That is exactly what the Selling-price calculator shows: price 125, fees at that price 37.50, profit 37.50, which is 30% of the price as asked.

The shortcut that misleads you

The common method: 30% fees plus 30% profit, so add 60% to cost. That gives 50 × 1.6 = 80. But at 80 the platform takes 30% of it, which is 24, leaving you just 6 after cost. That is a 7.5% margin, not 30%. The mistake is that both percentages are taken from the price, while the 60% was added to the cost.

Why the numbers explode near 100%

Hold fees at 30% and raise the margin step by step, cost staying at 50:

• 20% margin: price 100.
• 30% margin: price 125.
• 35% margin: price 142.86.
• 40% margin: price 166.67.
• 50% margin: price 250.
• 70% margin: the tool refuses, because the total is 100% and nothing of the price is left.

Each extra ten points does not add a fixed amount; it adds more than the step before, because you are dividing by a shrinking number. Close to 100% the required price becomes absurd, and then impossible.

What to do with this

If the solved price is higher than the market will pay, the fix is not to change the maths but one of the inputs: negotiate a lower cost, sell through a channel with a lower fee, or accept a smaller margin on this channel. Try each option in the calculator and watch the effect. You will usually find that shaving a few points off the fee saves more than you expect, for the same reason explained above. After selling, check the real margin on an order with the Profit margin calculator.