Binance API返回最小下单数量与UI不符问题咨询

调用Binance的fapi.binance.com/fapi/v1/exchangeInfo接口获取ETHUSDT永续合约信息时，出现了接口返回数据与UI显示不一致的情况：

• Binance UI显示ETH最小下单量为0.004ETH
• 接口返回的ETHUSDT数据中，filters数组里的LOT_SIZE和MARKET_LOT_SIZE过滤器的minQty字段值均为0.001

接口返回的完整数据如下：

{
  "symbol": "ETHUSDT",
  "pair": "ETHUSDT",
  "contractType": "PERPETUAL",
  "deliveryDate": 4133404800000,
  "onboardDate": 1569398400000,
  "status": "TRADING",
  "maintMarginPercent": "2.5000",
  "requiredMarginPercent": "5.0000",
  "baseAsset": "ETH",
  "quoteAsset": "USDT",
  "marginAsset": "USDT",
  "pricePrecision": 2,
  "quantityPrecision": 3,
  "baseAssetPrecision": 8,
  "quotePrecision": 8,
  "underlyingType": "COIN",
  "underlyingSubType": [
    "Layer-1"
  ],
  "settlePlan": 0,
  "triggerProtect": "0.0500",
  "liquidationFee": "0.015000",
  "marketTakeBound": "0.05",
  "filters": [
    {
      "minPrice": "39.86",
      "maxPrice": "306177",
      "filterType": "PRICE_FILTER",
      "tickSize": "0.01"
    },
    {
      "stepSize": "0.001",
      "filterType": "LOT_SIZE",
      "maxQty": "10000",
      "minQty": "0.001"
    },
    {
      "stepSize": "0.001",
      "filterType": "MARKET_LOT_SIZE",
      "maxQty": "2000",
      "minQty": "0.001"
    },
    {
      "limit": 200,
      "filterType": "MAX_NUM_ORDERS"
    },
    {
      "limit": 10,
      "filterType": "MAX_NUM_ALGO_ORDERS"
    },
    {
      "notional": "5",
      "filterType": "MIN_NOTIONAL"
    },
    {
      "multiplierDown": "0.9500",
      "multiplierUp": "1.0500",
      "multiplierDecimal": "4",
      "filterType": "PERCENT_PRICE"
    }
  ],
  "orderTypes": [
    "LIMIT",
    "MARKET",
    "STOP",
    "STOP_MARKET",
    "TAKE_PROFIT",
    "TAKE_PROFIT_MARKET",
    "TRAILING_STOP_MARKET"
  ],
  "timeInForce": [
    "GTC",
    "IOC",
    "FOK",
    "GTX"
  ]
}

这并非API Bug，而是你忽略了MIN_NOTIONAL过滤器的限制：

• 该过滤器要求下单的**名义价值（数量 × 当前价格）**至少为5USDT
• 假设当前ETH价格为1250USDT，0.001ETH的名义价值仅为1.25USDT，不满足5USDT的要求
• 实际最小下单量需满足：数量 ≥ 5 / 当前ETH价格，当价格为1250USDT时，计算结果为0.004ETH，这正是UI显示的数值

总结：API返回的minQty是下单数量的最小单位/精度，但实际下单需同时满足MIN_NOTIONAL的名义价值要求，UI显示的是两者中更严格的限制条件。

内容的提问来源于stack exchange，提问作者koto