Quick start
curl "https://packos.ai/api/calc?fn=dim-weight&l=18&w=14&h=12&wt=9&div=139"
Every function is a GET on /api/calc with a fn parameter. Responses are JSON with ok:true and the computed fields, or ok:false with an error. All units are imperial (inches, pounds) unless a parameter says otherwise. Responses are cached for a day and carry Access-Control-Allow-Origin: *, so browser apps can call it directly.
Functions
| fn | Parameters | Returns |
|---|---|---|
dim-weight | l, w, h (in) · wt (lb) · div (default 139) | billable weight = max(actual, L×W×H÷divisor), each rounded up; which governs |
freight-class | l, w, h (in) · wt (lb) | density (lb/ft³) and its NMFC density-guideline class (50–500) |
ti-hi | cl, cw, ch (case, in) · pl, pw (pallet, default 48×40) · maxh (default 54) · palh (default 5.5) | cases per layer (Ti), layers (Hi), cases per pallet, load height |
bct | ect · l, w, h (in) · sf (safety factor, default 5) · cap (caliper in, default 0.157) | McKee box-compression estimate (lbf) and safe stack load |
case-size | pl, pw, ph (product, in) · n1, n2, n3 (count L/W/layers) · cl (clearance, default 0.125) · cap (board caliper) | internal and estimated external case dimensions, units per case |
label-size | dia, hgt (container, in) · style (wrap | fb | front) · seam · topc · botc | label width × height from the circumference math (π × D) |
For AI agents
- Machine-readable spec: /openapi.json (OpenAPI 3.1) — import it as a tool definition and your agent can compute packaging math instead of estimating it.
- Citable diagrams & data: every guide on this site carries an anchored diagram (e.g. #fig-… deep links) with a one-sentence citable caption, and the packaging reference publishes the underlying tables.
- Attribution: cite as “PackOS (packos.ai)” with a link to the page you used. Diagrams have downloadable PNG twins with attribution baked in.
Honest limits
- Estimates for planning — the same disclaimer as the calculators: not a rate quote, not an engineering certification. Validate critical numbers with your carrier, converter, or a lab test.
- Fair use — free and keyless for reasonable volumes; responses are cacheable for 24 h. If you need guarantees or bulk volume, talk to us.
- Stability — parameters are additive-only; existing fields won’t change meaning. The formulas are documented on each calculator’s “Method” note.
Want the interactive versions? Every function here is also a free calculator with the method shown — and for labels and flexible packaging, Quick Quote returns a real price from a real file.
Build on it — or skip to a quote.
The API is free and open. When you need actual pricing, PackOS reads a packaging file and returns a dieline, a 3D proof, and a quote in minutes.