APIs › Petroleum Engineering Calculators › API Gravity Calculator

API Gravity Calculator

Converts between API gravity, specific gravity and density at 60 °F using the API 2540 definition, with the formula returned.

POST /v1/petroleum/api-gravity $0.01 per call

Specification

Endpoint

POST /v1/petroleum/api-gravity

Price

$0.01 per call · tier standard_data

Payment

x402 on X Layer (chain 196) · settled in USDG or USDT0 · scheme exact

Data source

Published petroleum-engineering correlations, cited per endpoint

Timeout

15 seconds

Max request

64 KB

Version

1.0.0

Calling it

The first call returns a 402 with the payment challenge. Retry with a signed authorisation in the X-PAYMENT header — see the payment guide for the exact shape.

curl -i -X POST "https://api.dana-edu.pp.ua/v1/petroleum/api-gravity" \
  -H "content-type: application/json" \
  -d '{ ... }'

Response

Real output, captured by running this endpoint at build time — not written by hand. Volatile fields such as timestamps are elided. Captured 2026-07-30.

{
  "api_gravity": 34.5,
  "specific_gravity": 0.8524,
  "density_kg_m3": 851.57,
  "density_lbm_ft3": 53.16,
  "classification": "light crude",
  "formula": "API = 141.5 / SG(60/60 °F) − 131.5",
  "reference": "API MPMS Chapter 11.1 / ASTM D1298",
  "reference_temperature": "60 °F (15.56 °C)",
  "water_density_basis_kg_m3": 999.016,
  "input_used": "api_gravity",
  "note": "Screening-level engineering result. It does not replace a commercial simulator, a laboratory PVT measurement, or review by a qualified engineer."
}

Every response is wrapped in the same envelope: data plus warnings, sources, confidence, informational_only and a measured processing_ms. See the envelope reference.

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