Perpetual funding cost calculator API

Compute perpetual-futures funding: cost = notional·fundingRate·intervals (longs pay shorts when the rate is positive), with the annualized funding rate from the interval length. Deterministic funding math. Answers 'how much funding will I pay','perp funding cost over a day','annualized funding rate'.

Price$0.01per request

MethodPOST

Route/v1/calc/cryptocalc-perp-funding-cost

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

calccryptodefiperpsfundingfuturesleveragetrading

API URLhttps://x402.hexl.dev/v1/calc/cryptocalc-perp-funding-cost

Integration docs

Example request

{
  "positionNotional": 50000,
  "fundingRate": 0.0001,
  "intervalsHeld": 3,
  "side": "long"
}

Example response

{
  "formula": "cost = notional·fundingRate·intervals (long pays when rate>0)",
  "side": "long",
  "positionNotional": 50000,
  "fundingRatePct": 0.01,
  "intervalsHeld": 3,
  "intervalHours": 8,
  "costPerInterval": 5,
  "totalFundingCost": 15,
  "annualizedFundingRatePct": 10.95,
  "note": "you pay funding"
}

Input schema

{
  "type": "object",
  "required": [
    "positionNotional",
    "fundingRate"
  ],
  "properties": {
    "positionNotional": {
      "type": "number",
      "description": "position notional (USD)",
      "examples": [
        50000
      ]
    },
    "fundingRate": {
      "type": "number",
      "description": "per-interval rate (decimal, can be negative)",
      "examples": [
        0.0001
      ]
    },
    "intervalsHeld": {
      "type": "number",
      "examples": [
        3
      ]
    },
    "intervalHours": {
      "type": "number",
      "description": "hours per funding interval",
      "examples": [
        8
      ]
    },
    "side": {
      "type": "string",
      "enum": [
        "long",
        "short"
      ],
      "examples": [
        "long"
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}