Our goal is to make each calculator understandable as well as useful. This page explains how formulas, assumptions, sources, testing and corrections are handled.
Calculator pages show the formula or calculation method whenever practical. Some tools use direct arithmetic or unit-conversion factors; others use standard financial, statistical or geometric formulas. When a calculator includes assumptions—such as a monthly compounding convention, a material waste allowance or a simplified overtime model—we try to state those assumptions near the calculator or in the supporting explanation.
A mathematically correct result can still be misleading if the inputs do not match the real situation. Rates, dimensions, dates, payroll rules, material densities and other inputs should be checked before relying on a result. For purchases, contracts, payroll, taxes, medical decisions or other high-stakes uses, verify the result with an appropriate authoritative source or qualified professional.
Not every calculator requires an external source: many rely on elementary arithmetic or standard mathematical identities. For calculators tied to health guidance, lending terminology, payroll law or other standards, we add references when they materially help visitors understand the basis or limitation of the calculation.
The current calculators run in JavaScript in the visitor's browser. The values entered into calculator fields are not intentionally sent to a server by the calculator engine. Hosting infrastructure may still create ordinary server logs when pages are requested; see the Privacy Policy for more detail.
We validate calculator configuration, input handling and calculation logic as the site is updated. We also compare important formulas with published references when a source is relevant. Because mistakes are still possible, we encourage visitors to report anything that appears incorrect.
Found an issue? Send the calculator URL, the inputs you used, the result you received and what you expected to info@erichcalculators.com or use the contact page.
The current calculator library does not require an account or payment to use the tools. If the site later adds optional products, advertising or other monetization, the calculators themselves can remain clearly separated from those additions.