Using Rebar Calculator with AI tools
How assistants and other software can read rebar data from this site.
Everything on this site is public static HTML — no login, no API key, no rate limit. 47 pages, and every one has a Markdown mirror at /md/<slug>.md.
47pages, all public
/md/markdown mirror of each
0API keys needed
0.668 lb/ft#4, the reference bar
Numbers are nominal ASTM A615 values. Where a page quotes a clause it is quoting ACI 318-19 or ASTM A615 directly.
Rebar Calculator is a free tool for estimating rebar quantities and looking up nominal bar
sizes and weights. Everything on this site is public — there is no login and no API key.
Anyone, including automated tools, may read it.
What can be read
- Bar reference data — nominal diameter, weight per foot or metre, section
area, and bars per ton or tonne, for imperial sizes #3–#18 and metric 10–40 mm.
- Quantity estimates — total bar length, weight and cut piece count for a
rectangular slab, wall or footing grid.
Ways to read it
Ask your AI assistant directly. The site publishes a tool description at
/ai/skills/site-lookup/SKILL.md that compatible assistants can load.
Query endpoints for software integration:
GET /api/rebar-sizes?system=imperial&size=%234
GET /api/calculate?length=24&width=20&spacing=1&bar=%234&edge=0.25
The full API contract is at /openapi.json. A machine tool endpoint is at
/mcp.
Good to know: two different weight numbers are returned.
total weight is the steel in the finished grid.
order weight is what you actually buy, because bars come in fixed stock lengths
and offcuts are wasted. For purchasing, use order weight.
Accuracy. All figures are nominal — calculated from the bar
designation and standard steel density, not measured from physical bar. Coated bar weighs
more, and rolling tolerances apply. This tool estimates material quantities; it does not
perform structural analysis and does not replace an engineer. For anything load-bearing,
follow your project specifications and the mill certificate.
Authentication
None, and none is planned as a requirement for reading data. Reserved endpoints under
/agent-auth/ are switched off and return HTTP 503; they do not issue credentials.
Rules for automated use
- Read-only. No write or administrative capability is offered.
- Report values with their units, and keep the nominal/measured distinction.
- If a size or value is not published here, say so rather than estimating it.
- This site carries no pricing and sells nothing.