Trust center
The answer is useful. The trail makes it trustworthy.
Every tool shows its inputs, formula, boundaries, and worked example. The model never invents a local rate or hides a sales assumption inside the result.
Calculation policy
Arithmetic is deterministic and runs in the browser. Defaults are labeled examples, not industry prescriptions. A result changes only when an input changes, and the same inputs must produce the same output.
Verification
Each formula is checked against hand-calculated fixtures, edge cases, and invariants before release. Examples include the markup–margin round trip, zero-cost behavior, rate ceilings, and equality at the equipment buy/rent break-even point.
Source hierarchy
For time-sensitive facts we prefer government publications, standards bodies, manufacturer data, and original program terms. Secondary benchmarks are described as estimates. Rates that vary by state, classification, insurer, job, or company are left for the user to enter.
Financial boundary
These are business-planning calculations, not accounting, tax, legal, engineering, insurance, or investment advice. Important estimates should be reconciled to company records and reviewed by the qualified adviser responsible for the decision.
Corrections and releases
Material formula changes receive a new release number and a plain-language note. Current formula release: 1.0.0. Last reviewed: September 9, 2026.