Source: https://guthlabs.ai/docs/instruments/compression-ratio-calculator/implementation/

instrument implementation / implementation-contract

# Compression Ratio Calculator implementation

A source-bound implementation contract for Compression Ratio Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-160

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero compressed size makes the compression ratio undefined and must be rejected or explicitly reported. The pasted-text mode also has an unresolved character-count versus encoded-byte convention, which can change the reported ratio, saving percentage, and bits per byte.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "original_size": 1000000,
    "compressed_size": 250000,
    "unit": "bytes"
  },
  "expected_outputs": {
    "ratio": 4,
    "saving_percent": 75,
    "effective_bits_per_original_byte": 2,
    "entropy_limit_lower_bound": null
  },
  "working": "ratio = 1,000,000 / 250,000 = 4. saving% = (1 - 250,000 / 1,000,000) × 100 = (1 - 0.25) × 100 = 0.75 × 100 = 75%. effective bits/byte = 8 × 250,000 / 1,000,000 = 8 × 0.25 = 2 bits per original byte. Entropy-limit lower bound = unavailable from sizes alone."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/compression-ratio-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/compression-ratio-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/compression-ratio-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`