API

The API runs the same calculator as the website. Each successful POST /api/v1/calculate uses one credit from your account; rejected input costs nothing. Create a key on your account page.

Authentication

Authorization: Bearer pfu_...

Endpoints

  • GET /api/v1/fixtures — fixture list and allowed option values (no key needed)
  • POST /api/v1/calculate — run a calculation (1 credit)
  • GET /api/v1/account — email and credit balance
  • GET /api/v1/usage?limit=50&before=ID — usage list, newest first
  • GET /api/v1/usage/ID — one saved calculation, with request and result

Example

curl -s https://plumbingfixtureunits.com/api/v1/calculate \
  -H "Authorization: Bearer $PFU_KEY" -H "Content-Type: application/json" \
  -d '{
  "fixtures": [
    {"fixture": "bathroom_group", "occupancy": "private", "supply": "flush_tank", "count": 12},
    {"fixture": "kitchen_sink",   "occupancy": "private", "supply": "faucet",     "count": 12}
  ],
  "system": "flush_tank",
  "continuous_gpm": 0,
  "side": "total",
  "tube_type": "L", "service": "cold", "c": 140,
  "pressure": {"street_psi": 55, "rise_ft": 25, "developed_length_ft": 300,
               "fixture_min": "flushmate_504", "meter_size": "2"}
}'

side is what the pipe carries: total (hot + cold, the default), cold or hot. Hot-only and cold-only lines use ¾ of the fixture units. pressure is optional. When present, give either fixture_min (a listed key) or fixture_min_psi, and either meter_size, meter_loss_psi, or neither (no meter).

Drainage example

curl -s https://plumbingfixtureunits.com/api/v1/calculate \
  -H "Authorization: Bearer $PFU_KEY" -H "Content-Type: application/json" \
  -d '{
  "method": "drainage",
  "slope": "1/4",
  "wc_rule": {"wc_on_3in": 3},
  "runs": [
    {"id": "Building drain", "type": "building_drain", "drains_into": null, "fixtures": []},
    {"id": "Branch A", "type": "branch", "drains_into": "Building drain",
     "fixtures": [{"fixture": "bathroom_group", "occupancy": "private", "count": 2},
                  {"fixture": "custom", "name": "Clothes washer", "dfu": 3, "count": 1,
                   "basis": "local code table"}]}
  ],
  "vents": {"planned": ["2", "2"], "method": "diameter_sum"}
}'

Each run lists the fixtures connected directly to it and the run it drains into; loads add up downstream. Size = the larger of the BMS 66 fixture-unit table size and the WC rule (false turns the rule off), and never smaller than a run feeding it. Fixtures not in BMS 66 Table 803 go in as custom with a rating and its basis. 1 credit per drainage calculation, separate from water.

Responses

  • 200 — {"usage_id", "credits_remaining", "result"}. The result carries version, time, sources, low-flow note and disclaimer.
  • 400 — {"error": "plain-English reason", "charged": false}
  • 401 — missing or bad API key
  • 402 — out of credits