Target Sell Price Calculator (with fees & tax)

Understanding the target sell price calculator — concept and principle

This calculator answers a simple trading question: at what price do I have to sell so that, after paying the commission on the purchase, the commission on the sale and any tax on the gain, I keep exactly the return I am aiming for? Investors use it to set limit orders and take-profit levels.

How it is calculated

First the true cost is found: cost = B × (1 + fb), where B is the buy price and fb the buy fee. The money you want to end with is goal = cost × (1 + t), where t is the target net return. Selling at S leaves S × (1 − fs) after the sell fee, and tax at rate tx is charged on the gain over cost. Setting the after-tax proceeds equal to the goal and solving for S gives:

S = (goal − tx × cost) ÷ ((1 − fs) × (1 − tx))

The break-even price (zero profit, so no tax) is cost ÷ (1 − fs). The required price rise is S ÷ B − 1, and the net profit per share is goal − cost.

The principle

Fees and tax are taken from the money that passes through them, so they cannot simply be added to the target percentage. A sell fee of 0.1% is charged on the sale price, which is already larger than the cost, and tax is charged only on the part above cost. Working backwards from the amount you want to keep, and dividing by the fractions that survive each deduction, gives the exact price. All percentages are treated as flat rates; fixed per-trade fees and minimum commissions are not modelled.

Worked example

1. Defaults: buy price $100, target 20%, buy fee 0.1%, sell fee 0.1%, tax 0%.
2. Cost incl. buy fee = 100 × 1.001 = $100.10.
3. Goal = 100.10 × 1.20 = $120.12, so the net profit is $20.02.
4. Sell price S = 120.12 ÷ 0.999 = $120.24 (no tax term because tx = 0).
5. Break-even = 100.10 ÷ 0.999 = $100.20; required rise = 120.24 ÷ 100 − 1 = 20.24%.

How to read the result

The gap between your target (20%) and the required rise (20.24%) is the cost of trading. With low online-broker fees it is small; with 1% fees on each side or a 20–25% tax on gains it becomes several percentage points. The break-even price is a useful reference for a stop: selling below it means a real loss even if the quote is above your buy price.

Common mistakes

• Adding fees to the target (20% + 0.2%) instead of solving for the price; the error grows with higher tax.
• Forgetting that the "net return" here is measured on cost including the buy fee, not on the raw buy price.
• Ignoring fixed fees, spreads, FX conversion or transaction taxes on the sale itself.

Frequently asked questions

Why is the required price rise bigger than my target?

Because the sell fee and tax are taken out of the sale proceeds before you receive them, the price has to overshoot the target to compensate.

How do I include a securities transaction tax charged on the sale?

A tax charged on the whole sale amount works like a sell fee, so add its rate to the sell fee field.

Can I use it for crypto with maker and taker fees?

Yes. Enter the fee you expect to pay on each side; the formula is the same.

Sources: Standard financial mathematics (percentage fees and taxation of gains)