Our calculation principles
- Separate meaningful guest groups. Adults and children receive different default portions where that distinction materially affects the result.
- Expose the portions. A default such as three pizza slices per adult is an editable starting point, not an invisible rule.
- Apply the buffer once. The visitor chooses a percentage buffer for seconds, uncertainty, and occasional extra guests.
- Round purchase units up. You cannot buy a fraction of a pizza or bottle, so the final shopping quantities round upward.
- Explain package assumptions. When a result uses 24 beers per case, five glasses per wine bottle, or 16 standard pours per spirits bottle, the page says so.
Testing and updates
Calculator logic is separated from the visual interface and covered by automated tests for representative scenarios and boundary cases. When assumptions or package conventions change, we update both the calculation and the explanation.
Alcohol estimates
Alcohol calculations are quantity-planning tools for adults of legal drinking age. They do not recommend consumption. Hosts remain responsible for local laws, responsible service, transportation planning, and nonalcoholic options.
Corrections
If an assumption is unclear or a result appears wrong, send the inputs and expected result through our contact page. We would rather correct the tool than defend a bad number.