ClearRand

Methodology

How we build, document and verify every calculator.

Our process

How we build every calculator

1

Define

Inputs, validation rules and result formats are written as typed definitions.

2

Verify

Every formula is unit-tested against known examples and boundary cases.

3

Document

Sources, assumptions, effective dates and limitations are shown on each page.

Each calculator is built from a typed definition that separates inputs, validation, the calculation itself, and result presentation. This keeps the logic testable, readable and independent of the UI.

Data and sources

  • Tax rates, rebates and thresholds come from official SARS publications.
  • Fuel prices are sourced from the Department of Mineral Resources and Energy.
  • Transfer duty and VAT rates come from SARS.
  • Solar, vehicle and property assumptions are clearly marked as estimates.

Verification

We unit-test every formula and boundary condition. When authoritative rules cannot be represented faithfully, we narrow the calculator's claim and show the limitation instead of guessing.

Updates

Data changes are released as new versions with a clear effective date. Each calculator page shows the last reviewed date and the version of data it is using.