How we check the math

A useful comparison shows its assumptions and leaves enough detail for you to check the answer.

Examples are labeled

The prices in our launch guides and calculator presets are illustrative. They do not establish availability, a retailer’s price, or a tested product’s performance. We do not invent shopping trips, hands-on tests, customer testimonials, or store relationships.

Arithmetic has a test

The calculators use shared arithmetic functions with automated tests for worked examples, zero values, unit mismatches, invalid inputs, and break-even cases. They carry unrounded values through calculations and round for display. We also check the forms in a browser. Tests establish the behavior we check; they do not guarantee that every possible input or retailer promotion is covered.

Sources and original work

Our worked scenarios and explanatory examples are created for this site. Where an article discusses outside guidance, it links to the relevant primary source, such as NIST’s unit-pricing material or the Federal Trade Commission’s shopping guidance. A source link is not an endorsement of this publication.

AI assistance

AI tools assist with drafting, editing, and implementation. We do not present AI-generated prose as a report of firsthand product testing. The launch material is focused on transparent calculations and cited consumer guidance. The publisher is responsible for reviewing what is released and addressing corrections.

Commercial independence

Just Bargains is an Amazon Associate: deal pages carry affiliate links, and we may earn a commission on qualifying purchases. The qualification rule is arithmetic, not commercial — a deal appears when its current price beats its own tracked price history by our thresholds, and leaves when it does not. No retailer paid for a recommendation in these guides. Any paid placement, if introduced, will be disclosed next to the relevant material. Advertisers do not change the numbers returned by a calculator.

Corrections

Use the contact page to report a factual or mathematical issue. Include the exact page, input values, and expected answer where possible. Material corrections will be recorded on the affected page with an updated date. We update dates for substantive revisions, not to make unchanged material appear new.