81 calculators traced to IRC, IBC, NEC, IECC, and IPC. Federal cost data refreshed monthly. 40,000+ certified product specs. REST + MCP. Every value cited.
api.buildcalcapi.dev
Each formula traces to IRC, IBC, NEC, IECC, IPC, ACI, TMS, DOE, or a US manufacturer spec sheet (GAF, USG, TCNA, Sherwin-Williams, Rust-Oleum). No made-up coefficients, no LLM guesses.
MCP = Model Context Protocol, Anthropic's standard for letting LLMs call
external tools. Streamable HTTP MCP endpoint at /mcp exposes
108 read-only tools to Claude Desktop, Cursor, or any MCP client. OAuth
2.1 + PKCE. Listed on the Anthropic MCP Registry.
RFC 7807 error responses, IETF rate-limit headers, Idempotency-Key support, Stripe metered billing, Customer Portal, GlitchTip error tracking, Better Stack uptime monitoring. No surprises.
Same Bearer token works for REST and MCP. Same calls work from cURL,
Python (buildcalcapi), TypeScript (@buildcalcapi/sdk),
or any MCP-compatible AI client.
# Sign up (60s, no card)
curl -X POST https://api.buildcalcapi.dev/v1/account/signup \
-H "Content-Type: application/json" \
-d '{"email":"[email protected]","payment_method_id":"pm_card_visa"}'
# → { "api_key": "bcapi_...", "tier": "free", "monthly_quota": 1000 }
# Concrete slab — ACI 318 cement coefficients
curl -X POST https://api.buildcalcapi.dev/v1/calc/concrete/yards \
-H "Authorization: Bearer bcapi_..." \
-H "Content-Type: application/json" \
-d '{"length_ft": 10, "width_ft": 10, "depth_in": 4}'
# → { "cubic_yards": 1.358, "bags_60lb": 62, "bags_80lb": 49,
# "source": "ACI 318 §5.2 + cement coverage tables" }
# Carpenter wages in LA County (BLS OEWS, refreshed monthly)
curl "https://api.buildcalcapi.dev/v1/costs/labor?soc=47-2031&geo_type=county&geo_value=06037" \
-H "Authorization: Bearer bcapi_..."
# → { "soc": "47-2031", "occupation": "Carpenters",
# "geo": { "county_fips": "06037", "name": "Los Angeles County, CA" },
# "median_hourly_wage_usd": 31.84, "annual_mean_wage_usd": 67860,
# "as_of": "2024-05",
# "source": "BLS OEWS May 2024 — bls.gov/oes/oes_arch.htm",
# "confidence": "tier_1_authoritative" }
Same 81 calculators + MCP server on every tier. Quota + RPM scale up.