You would do that by using appropriate symbol
for the trading pair: COMBOBTC
or BTCCOMBO
.
However, at the moment Binance does not offer this trading pair. You cannot buy or sell BTC for COMBO directly. You will have to go through an intermediate, for example: sell COMBO for USDT (using symbol=COMBOUSDT
), buy BTC with USDT (symbol=BTCUSDT
).
symbol=BTCEUR
is available though. Use that to buy or sell BTC for EUR.
In general, you need to look at the order book. For example:
curl 'https://api.binance.com/api/v3/depth?symbol=BTCEUR&limit=10'
Response
{
"lastUpdateId": 7212812426,
"bids": [
[
"52300.27000000",
"0.00345000"
],
[
"52300.26000000",
"0.00433000"
],
[
"52294.76000000",
"0.01435000"
],
[
"52294.75000000",
"0.02361000"
],
[
"52294.23000000",
"0.00015000"
],
[
"52292.28000000",
"0.01039000"
],
[
"52290.30000000",
"0.03697000"
],
[
"52290.29000000",
"0.02000000"
],
[
"52290.07000000",
"0.06411000"
],
[
"52288.98000000",
"0.03909000"
]
],
"asks": [
[
"52302.05000000",
"0.02000000"
],
[
"52302.06000000",
"0.02361000"
],
[
"52302.24000000",
"0.00021000"
],
[
"52303.33000000",
"0.00172000"
],
[
"52304.07000000",
"0.02297000"
],
[
"52304.11000000",
"0.03824000"
],
[
"52305.23000000",
"0.01300000"
],
[
"52305.68000000",
"0.01300000"
],
[
"52307.80000000",
"0.01204000"
],
[
"52308.76000000",
"0.00015000"
]
]
}
See asks
for offers to sell BTC for EUR. With the order book in that state, the best price is 52302.05 EUR for 1 BTC, so with 100 EUR you will be able to buy 0.00191 BTC (considering the minimum lot size 0.00001). If the offered quantity is less than what you need, you’d get the next best price, and so on.
For type=MARKET
orders you can use quoteOrderQty
parameter: for example quoteOrderQty=100
to buy as much BTC as possible at the current market price spending no more than 100 EUR.