Direct answer
Holding 0.1 BTC at an average of 60,000 USDT and planning to add at 54,000 USDT: reaching an average of 57,000 USDT takes 0.1000 BTC; 56,000 USDT takes 0.2000 BTC; 55,000 USDT takes 0.5000 BTC (27,000.00 USDT of notional); 54,500 USDT takes 1.1000 BTC. The closer the target to the add price, the faster the quantity grows, and margin at 10x climbs from 600.00 to 6,540.00 USDT.
The result first
Assume a holding of 0.1 BTC at an average of 60,000 USDT at 10x, with an add planned at 54,000 USDT. Enter the current fill, the add price and the target average in the average entry calculator and it shows the quantity to add.
A 57,000 USDT target needs 0.1000 BTC, leaving 11,400.00 USDT of notional and 1,140.00 USDT of margin; a 56,000 USDT target needs 0.2000 BTC, with 16,800.00 USDT of notional and 1,680.00 USDT of margin.
A 55,000 USDT target needs 0.5000 BTC, for 33,000.00 USDT of notional and 3,300.00 USDT of margin; a 54,500 USDT target needs 1.1000 BTC, for 65,400.00 USDT of notional and 6,540.00 USDT of margin.
The formula
Adding q at price P moves the average to (current notional + P × q) ÷ (current quantity + q). Setting that equal to a target T and solving gives q = current quantity × (current average − T) ÷ (T − P).
For a 55,000 target: q = 0.1 × (60,000 − 55,000) ÷ (55,000 − 54,000) = 0.1 × 5,000 ÷ 1,000 = 0.5 BTC. The denominator is the gap between target and add price: the smaller the gap, the larger q, and a target equal to the add price needs an infinite position.
A short works the same way in reverse: a 2 ETH short averaging 3,000 USDT that adds at 2,700 USDT to pull its average to 2,850 USDT needs another 2.0000 ETH.
Target average against quantity to add
Currently 0.1 BTC at an average of 60,000 USDT, adding at a fixed 54,000 USDT. Every row reproduces by entering the target average in the average entry calculator.
| Target average (USDT) | Add (BTC) | Add notional (USDT) | Notional after (USDT) | Margin at 10x (USDT) |
|---|---|---|---|---|
| 57,000 | 0.1000 | 5,400.00 | 11,400.00 | 1,140.00 |
| 56,000 | 0.2000 | 10,800.00 | 16,800.00 | 1,680.00 |
| 55,000 | 0.5000 | 27,000.00 | 33,000.00 | 3,300.00 |
| 54,500 | 1.1000 | 59,400.00 | 65,400.00 | 6,540.00 |
Reading the curve
Quantity to add q = 0.1 × (60,000 − T) ÷ (T − 54,000). Each step of T toward 54,000 shrinks the denominator and multiplies q: moving the target from 56,000 to 55,000 raises the quantity from 0.2 to 0.5; moving it to 54,500 makes it 1.1.
The curve exposes a common illusion: an average that looks only a few hundred USDT away can sit behind a position several times larger.
Working back a short
A 2 ETH short averaging 3,000 USDT, adding at 2,700 USDT to pull the average to 2,850 USDT: q = 2 × (3,000 − 2,850) ÷ (2,850 − 2,700) = 2.0000 ETH. The short is then 4 ETH, with 1,140.00 USDT of margin at 10x.
A short's target average must sit between the add price and the current average; the calculator says so when a target is out of reach rather than returning a negative quantity.
Put the risk budget before the target
A better order: decide the most this trade may lose, convert it into the most you can hold, then see how low the average can go. In this example, a budget that allows only 0.3 BTC can pull the average down to 56,000 USDT and no further.
The add need not be one price either: split it across levels, working out each level's quantity and the margin when fully built, so the position fits the budget even if every order fills.
Why the last stretch is so expensive
Moving the average from 60,000 to 57,000 (3,000 of distance) takes 0.1 BTC; moving it from 55,000 to 54,500 (500 of distance) takes another 0.6 BTC. The average can only approach the add price, never reach it, so each further point of average costs more.
A larger position moves the liquidation price and the risk together. With the position grown from 0.1 to 1.2 BTC and margin from 600.00 to 6,540.00 USDT, the same fall now loses twelve times as much. That the numbers can be worked out does not mean the account can bear them.
Before choosing how much to add
Decide the most this trade may lose, and work back the most you can add — rather than picking an attractive average first. If the target average needs a position beyond the risk budget, give up the target.
After adding, recalculate the liquidation price in the liquidation calculator with the new average and total quantity, and check margin mode, available balance and the estimated liquidation price in the exchange's order preview.
Official sources and calculation boundary
The quantity-weighted average after an add follows OKX's futures PnL rules; margin as notional divided by leverage follows Binance's leverage and margin documentation. The positions you can actually open are limited by maintenance tiers and account balance.
Open the matching calculatorNext checks in this series
Frequently asked questions
Can the average reach the add price?
No. It can only approach it; the closer the target to the add price, the larger the quantity, and equality would need an infinite position.
Does the derived quantity include fees?
No. The quantity only moves the average to the target; the add's own fee is charged on its notional separately, and the calculator's break-even includes fees.
Can the target average be below the add price?
Not for a long. The add price is the limit the average can approach; the target must sit between the add price and the current average, or the calculator says it cannot be reached.
How is margin after the add calculated?
Total notional after the add divided by leverage. For the 55,000 USDT target here, 33,000.00 USDT of notional needs 3,300.00 USDT of margin at 10x.