Accuracy, testing and limitations

How calculations are presented

Each calculator workspace groups related formulas. For each calculation mode, we describe the method, show a checkable numerical example and disclose important limitations. Display rounding does not change the underlying formula.

What the tools do not cover

Finance tools use simplified, constant-rate models and do not predict returns or replace product terms. Physics tools use the stated SI quantities and simplifying assumptions. Date tools use calendar dates and do not perform business-day or holiday scheduling. Education results depend on your institution’s official grading rules.

Input validation and practical checks

Inputs outside supported ranges may return errors rather than a result. File operations depend on your browser and third-party PDF libraries; complex, password-protected or unusual files may behave differently. Do not use a tool's result as the sole basis for high-stakes financial, health, engineering or legal decisions.

Processing, external services and privacy

Core calculator operations execute in the browser. PDF utilities may fetch code from external content delivery networks; advertisements and other third-party resources may also make network requests. See the privacy policy for current disclosures.

Corrections and feedback

If you find a formula error, send the tool name, mode, inputs, expected value and actual output through the contact page. Do not include confidential documents or personal financial information in reports.

Independent verification

Reference examples provide a starting point but are not proof of correctness for every input. Check consequential outputs using authoritative standards, primary documentation or an appropriate professional.