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API · /rebar-api

Rebar Calculator API

healthy 3,879 Subscribers

Reinforcement-steel (rebar) maths as an API, computed locally and deterministically. The area endpoint computes the cross-sectional area of a reinforcing bar, a = π/4·d², its mass per metre (a·7850/1e6, steel ρ = 7850 kg/m³), the total area and mass for a number of bars, and — given a required steel area — the number of bars needed and the area provided. The spacing endpoint lays out bars across a section: from the width, the cover, the bar diameter and either a centre-to-centre spacing or a bar count it returns the other, n = floor((width − 2·cover − d)/spacing) + 1, the total steel area and the area per metre of width. The ratio endpoint computes the reinforcement ratio ρ = As/(b·d) of a section from the steel area (or the bars) and the section width and effective depth, as a fraction and a percentage, the single number that governs whether a beam is under- or over-reinforced. Everything is computed locally and deterministically, so it is instant and private. Ideal for structural and site-engineering tools, reinforced-concrete detailing, bar-bending schedules and steel take-off, and civil-engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is rebar geometry and quantities; for concrete mix proportions use a concrete API.

#rebar #reinforcement #concrete #structural #civil-engineering #developer-tools
api.oanor.com/rebar-api
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Machine-readable spec so AI agents can integrate this API.

/api/rebar-api/openapi.json
/api/rebar-api/llms.txt

Discovery: GET /api/index.json lists every API.

Rebar Calculator API — live data on the oanor API marketplace

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
74 ms
Server probes · 24h
Subscribers
3,879
active
Total calls
76
last 7 days
status Full status page → · 12 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,000 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • Single-bar cross-sectional area endpoint
  • Metric and imperial bar designations
  • Deterministic instant results
  • 2000 calls/month for evaluation
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Starter

€9.00 /month

  • 20,000 calls / month
  • 5 requests / second
  • Hard cap (429 above quota, no overage)
  • All area + bar-weight endpoints
  • Development & lap-splice length calc
  • Bar-spacing and quantity helpers
  • 20k calls/month for small CAD tools
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Pro

€24.00 /month

  • 120,000 calls / month
  • 15 requests / second
  • Hard cap (429 above quota, no overage)
  • Full reinforcement-steel calc suite
  • Batch multi-bar area requests
  • Code-table bar sizes (ASTM + Euro)
  • 120k calls/month for design platforms
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Mega

€74.00 /month

  • 638,000 calls / month
  • 40 requests / second
  • Hard cap (429 above quota, no overage)
  • Unrestricted rebar engineering endpoints
  • High-throughput batch reinforcement maths
  • Priority support and 40 rps burst
  • 600k calls/month for production estimators
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Related APIs

Other APIs with overlapping tags.

Concrete Mix API — oanor API marketplace

Concrete Mix API

Concrete mix-design maths as an API, computed locally and deterministically. The mix endpoint breaks down a volume of concrete into its materials from a nominal mix ratio (cement:sand:aggregate, for example 1:2:4): it applies the 1.54 dry-volume allowance, then returns the cement in cubic metres, kilograms and 50 kg bags, the sand and aggregate volumes and masses, and the water from the water-cement ratio — the complete batch for the pour. The quantity endpoint computes the concrete volume of a slab, footing, or round or square column from its dimensions, adds a wastage allowance and gives the dry material volume. The watercement endpoint solves the water-cement ratio, the water or the cement from the other two — the single most important number for concrete strength and durability. Densities used are cement 1440, sand 1600 and aggregate 1450 kg/m³, with a 50 kg cement bag. Everything is computed locally and deterministically, so it is instant and private. Ideal for construction, estimating and site-engineering tools, material take-off and ordering, DIY and builder apps, and civil-engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is nominal volume-batch concrete estimating; for retaining-wall earth pressure use an earth-pressure API.

api.oanor.com/concrete-api

 Construction Calculator API — oanor API marketplace

Construction Calculator API

Construction and material estimating as an API — the everyday "how much do I need to buy" maths for building and renovation jobs, computed locally and deterministically from standard geometry and trade rules of thumb. The paint endpoint works out the litres and number of cans for a surface, allowing for the number of coats and the paint's coverage and deducting doors and windows. The tile endpoint computes how many tiles (and full boxes) a floor or wall area needs from the tile dimensions and a wastage allowance. The concrete endpoint gives the concrete volume in cubic metres, cubic yards and litres — and the number of pre-mix bags — for a slab, footing, wall or round column, with an optional batch quantity. The bricks endpoint computes how many bricks a wall needs from the brick size and mortar joint (default 215×65 mm brick with a 10 mm joint ≈ 60 bricks per square metre). Everything is computed locally and deterministically, so it is instant and private. Ideal for builders' merchants and trade apps, DIY and home-improvement tools, quoting and estimating software, and project planners. Pure local computation — no key, no third-party service, instant. Live, nothing stored. Estimates are guidance — allow for site conditions and follow the manufacturer's stated figures. 4 endpoints. This is materials estimating; for plain unit conversion use a unit-conversion API and for tyre or drivetrain maths use a tyre API.

api.oanor.com/buildcalc-api

 Riveted Joint API — oanor API marketplace

Riveted Joint API

Riveted-joint strength maths as an API, computed locally and deterministically — the shear, bearing and rivet-count numbers a structural, sheet-metal or aircraft fitter checks a riveted connection by. The shear-capacity endpoint gives the load a rivet group carries across its shanks = the rivet area (π/4·d²) × the shear strength × the number of rivets × the shear planes — a rivet in single shear is cut on one plane, in double shear (the centre plate of a butt joint with cover plates) on two, so it carries twice. The bearing-capacity endpoint gives the load the rivets can press against the sides of their holes before the plate crushes = the projected contact area (diameter × plate thickness) × the bearing strength × the number of rivets; thin plates fail in bearing long before the rivet shears, which is exactly why both must be checked — the joint strength is the lesser of the two. The rivets-required endpoint inverts it: the rivets a design load needs = the load ÷ the allowable load per rivet (area × allowable shear × planes), rounded up to a whole rivet, using the working shear (strength ÷ safety factor) not the raw value. Everything is computed locally and deterministically, so it is instant and private. Ideal for structural and sheet-metal estimating, mechanical-design and fastener tools, and engineering calculators. Pure local computation — no key, no third-party service, instant. Shank-shear and bearing only — also confirm edge tear-out and minimum pitch. 3 compute endpoints. For bolt preload and torque use a bolt-torque API; for thread geometry a thread API; for welded joints a welding API.

api.oanor.com/rivet-api

 Wind Load API — oanor API marketplace

Wind Load API

Structural wind-load maths as an API, computed locally and deterministically. The pressure endpoint computes the velocity (dynamic) pressure of wind, q = ½·ρ·v², from the wind speed and air density — the pressure the wind exerts when it is brought to rest against a surface — and also solves the wind speed back from a given pressure, reporting the speed in m/s, km/h and mph. The force endpoint computes the wind force on a surface, F = q·Cf·A, from the velocity pressure (or wind speed), the exposed area and a force coefficient (≈1.3 for a building wall, ≈1.2 for a flat plate), and — given a height — the overturning moment about the base. The beaufort endpoint converts between a wind speed and the Beaufort scale using v = 0.836·B^1.5, returning the Beaufort number, the standard description from calm to hurricane force and the corresponding pressure. Everything is computed locally and deterministically, so it is instant and private. Ideal for structural and façade-engineering tools, signage, solar-array, scaffold and temporary-structure wind checks, sailing and meteorology apps, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is structural wind pressure and force; for wind-turbine energy output use a wind-power API.

api.oanor.com/windload-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Rebar Calculator API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Rebar Calculator API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Rebar Calculator API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Rebar Calculator API cost?
Rebar Calculator API has a free tier with 100 calls / month. Paid plans start at €9.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Rebar Calculator API GDPR-compliant?
All requests to Rebar Calculator API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/rebar-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/rebar-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/rebar-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/rebar-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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