Estimate Order Fee

Endpoint Information

Endpoint: POST /api/v1/orders/estimate_charge

Description: Estimate order fee with automatic exchange rate conversion. The backend automatically resolves the asset precision on the target chain based on chain_id and target_currency, returning price_target and charge_target in the correct native precision.

Authentication: API Key + Signature. See Authorization

Note: This is a Maker API endpoint. The X-Maker-Addr header is required and must be included in both the request headers and signature string.

Request Parameters

Field	Type	Required	Description
is_buy	bool	Yes	Whether it's a buy order
ticker	string	Yes	Stock symbol
exchange	int	Yes	Exchange code (0=US Stock, 1=HK Stock)
quantity	string	Yes	Quantity (regular precision)
price	string	Yes	Stock's native currency price (regular precision, NOT wei) USD for US stocks, HKD for HK stocks
asset	string	No	Asset contract address. If provided, it must match the address resolved from target_currency on the specified chain — a mismatch returns a 400 error
target_currency	string	No	Target stablecoin (USDT or USDC), defaults to USDT. The backend resolves the corresponding contract address from the chain whitelist
chain_id	int	No	Chain ID used to resolve the asset address and precision. Defaults to the default chain (BSC) if not provided

Response Parameters

Field	Type	Description
base_currency	string	Base currency (USD for US stocks, HKD for HK stocks)
charge_base	string	Fee in base currency (regular precision)
target_currency	string	Target stablecoin (USDT or USDC)
charge_target	string	Fee in target stablecoin (native precision of the asset on the target chain)
price_base	string	Price in base currency (regular precision, same as request price)
price_target	string	Price in target currency (native precision of the asset on the target chain)
exchange_rate	float	Exchange rate from base currency to target currency
chain_id	int	The chain ID used for this estimate
asset_address	string	The resolved asset contract address on the target chain (derived from target_currency and chain_id)

Precision Reference

charge_target and price_target precision is determined by chain_id and asset. The backend queries the on-chain contract dynamically:

Chain	chain_id	USDT Decimals	Example: 260 USD
BSC (default)	56	18	260000000000000000000
HashKey Chain	177	6	260000000

These fields can be used directly as the price and incentive fields when constructing an order — no client-side precision conversion needed.

Request Examples

BSC (omit chain_id, uses default)

curl -X POST "{API_BASE_URL}/api/v1/orders/estimate_charge" \
     -H "X-API-Key: YOUR_API_KEY" \
     -H "X-Maker-Addr: YOUR_MAKER_ADDRESS" \
     -H "X-API-Timestamp: 1715100000000" \
     -H "X-API-Signature: GENERATED_SIGNATURE" \
     -H "Content-Type: application/json" \
     -d '{
       "is_buy": true,
       "ticker": "AAPLs",
       "exchange": 0,
       "quantity": "100",
       "price": "260",
       "target_currency": "USDT",
       "chain_id": 56
     }'

HashKey Chain

curl -X POST "{API_BASE_URL}/api/v1/orders/estimate_charge" \
     -H "X-API-Key: YOUR_API_KEY" \
     -H "X-Maker-Addr: YOUR_MAKER_ADDRESS" \
     -H "X-API-Timestamp: 1715100000000" \
     -H "X-API-Signature: GENERATED_SIGNATURE" \
     -H "Content-Type: application/json" \
     -d '{
       "is_buy": true,
       "ticker": "AAPLs",
       "exchange": 0,
       "quantity": "100",
       "price": "260",
       "target_currency": "USDT",
       "chain_id": 177
     }'

Response Examples

BSC (USDT 18 decimals)

{
    "code": 0,
    "data": {
        "base_currency": "USD",
        "charge_base": "3.36",
        "target_currency": "USDT",
        "charge_target": "3377745527638190000",
        "price_base": "260",
        "price_target": "261373165829145650000",
        "exchange_rate": 0.994746339683381,
        "chain_id": 56,
        "asset_address": "0x55d398326f99059fF775485246999027B3197955"
    }
}

HashKey Chain (USDT 6 decimals)

{
    "code": 0,
    "data": {
        "base_currency": "USD",
        "charge_base": "3.36",
        "target_currency": "USDT",
        "charge_target": "3377745",
        "price_base": "260",
        "price_target": "261373165",
        "exchange_rate": 0.994746339683381,
        "chain_id": 177,
        "asset_address": "0xTokenAddressOnHashKey"
    }
}

Notes

• Input precision: quantity and price use regular human-readable precision — do not pass wei values
• Output precision: charge_target and price_target use the native precision of the asset on the target chain, and can be used directly as order fields
• Asset address resolution: asset_address in the response is resolved from target_currency + chain_id via the server-side whitelist. Clients can use this value directly as the asset field when constructing an order
• Asset validation: If asset is provided in the request, it must exactly match the address resolved from target_currency on the specified chain. A mismatch returns a 400 error
• Different chains use different precisions for the same stablecoin (BSC USDT=18, HashKey USDT=6) — always pass the correct chain_id to get the right precision
• Fee estimate is for reference only; actual fee is determined at transaction time