Metadata-Version: 2.4
Name: chargeable-weight
Version: 0.1.0
Summary: Calculate volumetric (dimensional) and chargeable weight for air, courier, sea, road, and rail freight
Author: krishnanz550i-cmyk
License: MIT
Project-URL: Homepage, https://github.com/krishnanz550i-cmyk/chargeable-weight
Project-URL: Issues, https://github.com/krishnanz550i-cmyk/chargeable-weight/issues
Keywords: logistics,freight,shipping,volumetric weight,dimensional weight,supply chain
Classifier: Development Status :: 3 - Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python :: 3
Classifier: Topic :: Office/Business
Classifier: Topic :: Scientific/Engineering
Requires-Python: >=3.8
Description-Content-Type: text/markdown
License-File: LICENSE
Provides-Extra: dev
Requires-Dist: pytest; extra == "dev"
Dynamic: license-file

# chargeable-weight

Calculate volumetric (dimensional) weight and chargeable weight for air,
courier, sea, road, and rail freight shipments.

Carriers bill shipments based on whichever is greater: the **actual
weight** or the **volumetric weight** (calculated from package
dimensions). This library implements that calculation cleanly, with
support for multiple units, transport modes, named divisor presets, and
multi-package consignments.

## Install

```bash
pip install chargeable-weight
```

## Quick start

```python
from chargeable_weight import calculate

result = calculate(
    length=60, width=40, height=40, unit="cm",
    actual_weight=18, weight_unit="kg",
    mode="air",
)

print(result.volumetric_weight_kg)   # 19.2
print(result.chargeable_weight_kg)   # 19.2
print(result.basis)                  # "volumetric"
```

## Supported modes and default divisors

| Mode      | Default divisor (cm³/kg) |
|-----------|---------------------------|
| `air`     | 6000 |
| `courier` | 5000 |
| `road`    | 3000 |
| `rail`    | 3000 |
| `sea`     | N/A (uses CBM × 1000, see below) |

These are sensible starting defaults based on common conventions seen
across the freight and parcel industry. They are **not** tied to any
specific carrier - always confirm the applicable divisor with your own
carrier or contract for billing-critical calculations.

## Divisor presets

Two divisor values - 5000 and 6000 - are both widely used across the
industry, often for different services, regions, or contracts (sometimes
even by the same carrier depending on the product). Rather than guessing
which one applies to your situation, you can refer to them by generic
preset labels and swap between them easily:

| Preset | Divisor |
|--------|---------|
| `"a"`  | 5000 |
| `"b"`  | 6000 |

```python
# Same package, two different divisor conventions
pkg = dict(length=60, width=40, height=40, actual_weight=10, mode="air")

result_a = calculate(**pkg, divisor_preset="a")  # divisor 5000
result_b = calculate(**pkg, divisor_preset="b")  # divisor 6000

print(result_a.volumetric_weight_kg)  # 19.2
print(result_b.volumetric_weight_kg)  # 16.0
```

This makes it easy to compare "what would this shipment cost under each
convention" without hardcoding either value, and to plug in your own
carrier's documented divisor (whether that happens to be 5000, 6000, or
something else entirely) via `divisor_preset` or a raw `divisor=` value.

You can also pass an explicit divisor directly, which overrides any preset:

```python
result = calculate(**pkg, divisor=4500)
```

## Units

### Input units

Dimensions accept `cm`, `m`, `mm`, `in`, `ft` (default `cm`).
Weights accept `kg`, `g`, `lb`, `oz` (default `kg`).

```python
result = calculate(
    length=20, width=15, height=10, unit="in",
    actual_weight=5, weight_unit="lb",
    mode="courier",
)
```

### Output units (always normalized)

Regardless of the input units you choose, **all results are returned in
a single fixed unit system**:

| Field | Unit |
|-------|------|
| `actual_weight_kg`, `volumetric_weight_kg`, `chargeable_weight_kg` | kilograms (kg) |
| `volume_m3` | cubic meters (m³) |

The input units (`unit`, `weight_unit`) are only used to *interpret* the
numbers you pass in - they are converted to centimeters and kilograms
internally before any calculation happens. The output is never expressed
back in the input units.

For example, these two calls describe the same physical package and
return (effectively) the same result, in kg/m³, even though one is given
in inches/pounds and the other in cm/kg:

```python
calculate(length=50, width=40, height=40, unit="cm",
          actual_weight=10, weight_unit="kg", mode="air")

calculate(length=19.685, width=15.748, height=15.748, unit="in",
          actual_weight=22.0462, weight_unit="lb", mode="air")

# Both return approximately:
# volumetric_weight_kg: 13.333
# volume_m3: 0.08
```

If you need the result in a different unit (e.g. pounds), convert the
returned kg value yourself - the library does not provide unit conversion
on outputs.


## Sea freight (CBM)

Sea freight chargeable weight is derived from volume in cubic meters
(CBM), using the common 1 CBM ≈ 1000 kg convention:

```python
result = calculate(
    length=1, width=1, height=1, unit="m",
    actual_weight=500, mode="sea",
)
print(result.volumetric_weight_kg)  # 1000.0
```

Divisor presets are ignored for sea mode, since it uses a CBM-based
calculation rather than a divisor.

## Multi-package consignments

```python
from chargeable_weight import calculate_consignment

packages = [
    {"length": 50, "width": 40, "height": 40, "actual_weight": 10},
    {"length": 60, "width": 40, "height": 40, "actual_weight": 25, "quantity": 2},
]

result = calculate_consignment(packages, mode="air")

print(result.total_actual_weight_kg)
print(result.total_volumetric_weight_kg)
print(result.total_chargeable_weight_kg)
```

By default, totals are compared (`sum(actual)` vs `sum(volumetric)`).
Some couriers calculate chargeable weight per package and sum those - use
`per_piece=True` for that behavior:

```python
result = calculate_consignment(packages, mode="air", per_piece=True)
```

## Disclaimer

This library implements widely-used industry conventions for
illustrative and estimation purposes. Divisors and CBM ratios vary by
carrier, service level, region, and contract terms. Always confirm exact
billing methodology with your carrier or freight forwarder for
invoicing-critical calculations.

## License

MIT
