Calcs.com for

A structural calculation API your users can defend

Add verified calculations to your software through the Calcs.com API. Results come from the same standards-aligned engine engineers already sign off on, so you ship the feature without building the engine.

Talk to us about connecting See how it works

Request

POST/v1/projects

curl --request POST \
  --url https://api.calcs.com/v1/projects \
  --header 'Authorization: Bearer $CALCS_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "name": "Smith residence"
  }'

Replay of a real run. Nothing is sent from this page.

Response

Not sent

Send the request to see the response

What your user sees

Floor joist J1

2x10 D.Fir-L No. 1 · 16 in o.c. · 14 ft span · 10 psf dead, 40 psf live

Create a project, then run the calculation.

The problem software vendors face

A code edition changes. Somewhere in your codebase, a hard-coded reading of the old one keeps running. Meanwhile your users expect calculations, standards checks, and AI assistance inside your product.

Years to build, never finished

Standards-checked calculation logic takes years to write. Every code update then pulls your team off the roadmap and back onto maintenance.

Quietly out of date

A hard-coded interpretation goes stale when the standard changes. Your users find out on a live project, not in a release note.

Hard to defend

Logic copied from PDFs has no path back to the source clause and carries licensing risk. When an engineer asks why a check passed, you have nothing to point to.

Connect once, stay current

Calcs.com is a standards-aligned calculation platform for structural engineers in the US, Canada, Australia, and New Zealand. CalcsConnect is the structural calculation API from Calcs.com. It gives your software the same verified calculators engineers use today, built to AISC, AISI, ASCE, CSA, NBCC, and AS/NZS standards. When a standard changes, the connected logic updates and your integration does not drift.

How the calculation API works

Your product keeps its interface and its users. Calcs.com runs the calculation underneath.

Your product sends the inputs

A user draws a member, generates a layout, or runs a check. Your software passes the inputs to the API.

Floor framing

Example product, not a real app

Floor joist J1

2x8 D.Fir-L No. 1 joist, 16 in o.c.

Joist section

Fails at 122%

Live load deflection governs: L/295 against L/360.

12 x 14 ft floor bay. Joists at 16 in o.c. on two 12 ft girders. 10 psf dead, 40 psf live. Girders: 2x12.

A verified calculator applies the standard

The same calculators behind the sheets engineers sign off on in Calcs.com run the check.

Choose the calculator

Calcs.com

The library holds 147 calculators. Your request names the one it wants by code.

Wood Beam (ASD)timberBeamASDNDS-2024
Wood Beam (LRFD)timberBeamLRFDNDS-2024
Wood BeamtimberBeamCA
Timber BeamtimberBeamNZS3603-1993

Replay of real runs. Rows are from the live catalogue.

The result comes back traceable

Formulas, assumptions, and standards references are visible in Calcs.com for every calculator your product calls.

Check the result

Your product

Floor joist J1

2x8 D.Fir-L No. 1 joist, 16 in o.c.

passed: false
summaryCheck: 1.220How close the governing check is to its limit (122%)
summaryCheckReferenceId: delta_ST_summaryWhich check governed: live load deflection

Re-check it by hand

Live load deflection

limit L/360 ÷ achieved L/295 = 360 ÷ 295

= 1.22againstsummaryCheck 1.220Matches

What went in

Member: 2x8 D.Fir-L No. 1 joist, 16 in o.c.
Span: 14 ft
Loads: 10 psf dead, 40 psf live
Deflection limits: L/360 live load, L/240 long-term

Open the sheet in Calcs.com to read the formulas, assumptions and references behind the live load deflection check.

Replay of a real run, trimmed for display. Nothing is sent from this page.

Connect the calculation layer

Call calculators from your own product, pipelines, or AI features. Your AI sends inputs to a verified calculator, so the engine never estimates a result.

What calls it

What Calcs.com does

Calcs.com engine

Run calculations from your product
Trigger a calc and return the result backed by the standard it was checked against, without opening Calcs.com.
Get site design data from coordinates
Drop a pin and return design values for wind, snow, seismic, and other environmental loads supported by Calcs.com.
Manage projects programmatically
Create, organize, list, and link projects so calculation work stays connected to your users' workflows.

What comes back

Your code calls the REST API

Create a project, then run a calculation with the inputs your user already has. These are the two calls from the demo above.

curl --request POST \
  --url https://api.calcs.com/v1/templates/timberBeamASDNDS-2024/calculate \
  --header 'Authorization: Bearer $CALCS_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "projectId": "00000000-0000-4000-8000-000000000001",
    "preset": "floorJoist",
    "name": "Floor joist J1",
    "attributes": {
      "member": "2x10 D.Fir-L No. 1",
      "L_X": 14,
      "spacing": 16
    }
  }'

Out

A solved sheet, as data

The response says whether the member passes, which check governs and by how much. Trimmed here; the full response carries every result field.

{
  "sheetId": "00000000-0000-4000-8000-000000000002",
  "templateCode": "timberBeamASDNDS-2024",
  "passed": true,
  "summaryCheck": 0.759,
  "summaryCheckReferenceId": "M_check",
  "summaryCheckError": false,
  "results": {
    "member": "2x10 D.Fir-L No. 1",
    "M_check": "1712 lb*ft / 2255 lb*ft",
    "V_check": "489 lb / 1665 lb",
    "R_check": "489 lb / 2812 lb",
    "delta_ST_summary": "-0.274 in (L/613)",
    "delta_LT_summary": "-0.317 in (L/531)",
    "...": "124 more fields"
  }
}

Validate against jobs you already ran

Run the API on projects already completed in Calcs.com and compare the results line by line. You see where the numbers match before you commit to anything.

Real projects, not demo data

Your team tests the engine on work engineers have already signed off.

Differences you can trace

Any gap points to a formula or an assumption, not a black box.

No change to your product

Your interface, users, and existing logic stay as they are while you compare.

Proven in live integrations

An AI-native structural design company is piloting the API today. Every load, rafter, and joist in a generated house plan runs through Calcs.com as the validation layer.

The engine behind the API

13.5M

Calculations run on Calcs.com.

81,000

Projects run on the platform each year.

228

Calculators in the library.

Trust & quality

Why results hold up

Engineers sign off on what they can inspect. The API runs the same calculators, so your users inherit that trust instead of relying on logic you wrote and have to defend.

An allowable area check in Calcs.com beside its references panel, citing IBC 2018, 2021 and 2024 clause 506.2.1

Transparent by design

Engineers can inspect formulas, variables, and standards references before relying on a result.

A bolted plate connection in Calcs.com with its description, its AISC Steel Construction Manual reference and its checks

Maintained when standards change

Calculators are updated when codes are, so your users stay current without a release from you.

The in-app support form in Calcs.com, with the footing calculation the question is about open beside it

Built and supported by engineers

Qualified engineers build the calculators and answer questions engineer to engineer.

Frequently asked questions

Do we have to give up our own interface?

No. Your product keeps its interface, branding, and users. Calcs.com provides the verified calculation underneath through the API.

What if we already built our own calculation logic?

That shows the need is real. The question is whether keeping standards-aligned logic current as codes change is where you want your team's time. You can validate the API against your own results on completed jobs before changing anything.

How is this different from copying standards into our code?

Copied logic has no link to the source clause and goes stale at the next edition. Calcs.com keeps calculators aligned to the standard and updates them when it changes, through controlled, licensed channels.

Can our AI features use it?

Yes. Your AI identifies which calculation applies and sends the inputs to a verified calculator. The calculator does the math, so results are repeatable and checkable. Engineers still verify outputs before relying on them.

Which standards does the API cover?

Calcs.com calculators cover AISC, AISI, ASCE, CSA, NBCC, and AS/NZS standards. Tell us which calculation your product needs and we will confirm coverage and edition before you build.

Talk to our team

Start with one moment in your product where a result must hold up under review. We map it to calculators already in Calcs.com and run them against jobs you have completed.

Talk to us about connecting

See how it works

Identify where your product needs a defensible result
Match it to calculators already in Calcs.com
Validate the results against completed projects