How We Verify Our Calculators
A party calculator is only useful if the numbers behind it hold up on the day. Too little wine, too few toilets or an under-ordered buffet is exactly what these tools exist to prevent, so every figure on this site is checked against a real source rather than guessed. This page explains the process we follow.
The process
- ✓Every quantity traces to a named source category: UK catering portion and drinks-planning conventions, standard UK drinks measures (75cl wine bottles, 25ml spirit measures), manufacturer data such as Qualatex helium charts, published supplier rates such as Royal Mail postage, and official guidance including the Purple Guide and FSA allergen guidance.
- ✓Where an event touches on safety or accessibility, we use the authoritative UK source directly: the Purple Guide (Events Industry Forum) for event toilet provision, BS 8300 for accessible parking, and the Equality Act 2010 for accessible facilities.
- ✓Every calculator is tested against hand-worked examples: we work the sums out on paper from the source figures and compare them with what the calculator returns, across an automated test suite run on desktop and mobile browsers before every deployment.
- ✓The site has been through repeated adversarial re-checks in which each figure is re-derived from its source from scratch, rather than assumed correct because it was there before. When a check disagrees with the code, we fix the code.
- ✓Errors reported through the feedback buttons on every calculator are investigated against the source, fixed, and re-verified before the fix goes live.
- ✓Content is reviewed when sources change, for example when supplier rates or official guidance are updated, and every calculator carries a last-updated date.
Verified, not guaranteed
These calculators give planning estimates, not guarantees or professional advice. Guest appetites, weather and event style all vary, so confirm final quantities with your caterer, florist, bar supplier or hire company before ordering, and always allow a sensible margin. For large public events, allergen management or anything licensing-related, take advice from a professional event organiser or your local authority.
Spotted an error?
Every calculator page has feedback buttons. If a figure looks wrong, tell us what you entered and what you expected: we investigate against the original source, fix anything that fails the check, and re-verify before the correction goes live. When a report shows a genuine error, the fix lands on the affected page itself, with a dated correction note where it matters.