Source: https://guthlabs.ai/docs/instruments/mtbf-mttr-reliability-calculator/implementation/

instrument implementation / implementation-contract

# MTBF / MTTR / Reliability Calculator implementation

A source-bound implementation contract for MTBF / MTTR / Reliability 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**: t5-059

**Effect**: Computation or source lookup only

## Input and validation requirements

The MTBF = 0 and MTTR = 0 input produces the undefined expression 0/0 and must be rejected. The calculator also has an explicit annual-downtime convention sensitivity when the input time unit is days.

## 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": {
    "MTBF_hours": 1000,
    "MTTR_hours": 10,
    "topology": "single",
    "component_count": 1
  },
  "expected_outputs": {
    "component_availability": 0.9900990099,
    "system_availability": 0.9900990099,
    "downtime_per_year_hours": 86.7326732673
  },
  "working": "A=MTBF/(MTBF+MTTR)=1000/(1000+10)=1000/1010=100/101=0.9900990099. Downtime/year=(1-A)*8760=(1-100/101)*8760=(1/101)*8760=8760/101=86.7326732673 hours."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/mtbf-mttr-reliability-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/mtbf-mttr-reliability-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/mtbf-mttr-reliability-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-tranche5/tranche5-results.json`