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OpenAPI Specification

openapi: 3.2.0
info:
  title: emission-factors.com Calculate API
  version: 2.1.0
  description: 'US electricity and fuel emission data by ZIP code: EPA eGRID Scope 2 factors (location-based) with the Green-e residual mix (market-based), Scope 1 fuel factors, EIA retail rates and hourly grid intensity, EPA CAMD plant emissions and OpenEI utility tariffs. Free, no key. Query parameters and JSON body fields not listed here are rejected with 400.'
  contact:
    url: https://emission-factors.com
  license:
    name: 'Data licenses vary by source: US government works (public domain); eGRID2024, GHG Hub 2026, OpenEI URDB and ZIP-to-utility data, and GeoNames are CC-BY-4.0; the Green-e residual mix is published by the Center for Resource Solutions. See /methodology.'
    url: https://emission-factors.com/methodology
servers:
- url: https://emission-factors.com
  description: Production
tags:
- name: Calculate
paths:
  /api/calculate:
    post:
      summary: Calculate Scope 2 CO₂e for a ZIP + kWh, location-based and market-based
      description: candidates[].co2e_kg is location-based (eGRID). candidates[].market_based.co2e_kg applies the Green-e residual mix to kWh not covered by contractual instruments (renewable_kwh).
      operationId: calculate
      x-unknown-field-hint: 'kwh is always in kWh: convert MWh x 1000 before sending.'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
              - zip
              - kwh
              properties:
                zip:
                  type: string
                  example: '94105'
                kwh:
                  type: number
                  example: 500
                year:
                  type: string
                  enum:
                  - '2023'
                  - '2024'
                  description: eGRID edition (default 2023); market-based needs 2023
                renewable_kwh:
                  type: number
                  example: 100
                  description: kWh covered by RECs, PPAs or green tariffs (market-based method). Default 0, max kwh.
      responses:
        '200':
          description: CO₂e calculation result (location- and market-based)
        '400':
          description: Missing or invalid fields, malformed ZIP, invalid year, or unknown fields (e.g. "unit"; kwh is always kWh)
        '404':
          description: Well-formed ZIP with no eGRID subregion (PO box, unique ZIP)
      tags:
      - Calculate