Start with people, but never assign drinks to them
Record three planning counts:
- All guests: the basis for water, glassware and a complete alcohol-free offer.
- Adults who may choose alcohol: a maximum selector count, not a list of expected drinkers.
- Guests known to need alcohol-free service: including under-18s, designated drivers and anyone who has asked for it—without recording private reasons.
Do not attach a number of alcoholic drinks to an individual guest. The party drinks calculator asks the host to choose a capped stock assumption from zero to six available serves per adult who may choose alcohol. Event length does not increase that alcohol number.
Every guest must be able to choose water and appealing alcohol-free drinks without explanation, delay or inferior glassware. Build that route first.
Build water and alcohol-free stock as independent rows
The calculator uses two disclosed shopping assumptions:
- 500 ml of soft or alcohol-free drink per guest.
- 250 ml of water per guest per event hour.
These are Unflustered Host stock assumptions, not NHS hydration instructions or claims about what a person needs. Weather, food, venue, refillable tap water, travel and the actual guests can change the shopping decision.
Split the totals into exact products only after checking preferences, ingredients, allergens, pack size, fridge capacity and serving route. Keep tap water visible even when bottled water is included. Do not count spirit mixer as the complete alcohol-free offer unless guests have actually accepted those products for that purpose.
Cap optional alcohol stock before choosing the mix
Choose the maximum alcoholic serves the event will make available, including any existing stock. This is a procurement control. It must not be used to encourage finishing bottles, topping up without agreement or matching another guest.
The calculator multiplies:
Planned alcohol stock serves = ceiling(adults who may choose alcohol × host-selected available serves)
It then allocates that integer across still wine, beer or cider, sparkling wine and spirits using the shares you enter. If the shares do not total 100%, it normalises their relative proportions visibly. If all four are zero while a positive alcohol stock is selected, it uses the displayed 40/40/10/10 starting mix rather than silently losing serves.
Zero is a valid input. Alcohol-free hosting is complete hosting.
Convert serves to exact containers and show surplus
The calculator currently uses these container assumptions:
- Six 125 ml serves from one 750 ml still-wine bottle.
- One exact 330 ml beer or cider container per serve.
- Six 125 ml serves from one 750 ml sparkling-wine bottle.
- Twenty-eight 25 ml serves from one 700 ml spirit bottle.
Check the exact label, package and intended measure. A 175 ml glass, 440 ml can or 35 ml spirit measure changes the yield. Calculate:
Containers = ceiling(planned category serves ÷ exact full serves per container)
Container surplus = containers × exact full serves − planned category serves
Surplus is unopened or unallocated capacity—not a reason to serve more. A spirit category with only two planned measures may require no purchase when a suitable labelled bottle already exists; if a bottle is bought, almost all of it should remain controlled reserve.
Worked example: a fictional 24-person stock ceiling
This example proves the arithmetic. It does not recommend alcohol consumption.
- 24 total guests; 14 adults may choose alcohol.
- The host selects 1.5 alcoholic serves available per possible selector.
- ceiling(14 × 1.5) = 21 planned alcohol-stock serves.
- A 40/40/10/10 mix becomes 9 still-wine, 8 beer/cider, 2 sparkling and 2 spirit serves after whole-serve allocation.
- Still wine: ceiling(9 ÷ 6) = 2 bottles, capacity 12, surplus 3 serves.
- Beer/cider: 8 exact 330 ml containers.
- Sparkling: ceiling(2 ÷ 6) = 1 bottle, capacity 6, surplus 4 serves.
- Spirits: ceiling(2 ÷ 28) = 1 bottle only if no suitable existing stock, capacity 28, surplus 26 measures.
The model also starts at 12 litres of soft drinks and 24 litres of water for a four-hour event. Those are separate shopping prompts to revise against the venue and actual offer—not amounts assigned to guests. The large container surpluses show why counting bottles without retaining reserve can turn a capped stock plan into an uncapped service.
Use units to describe stock, never to certify safety
The NHS formula is:
UK units = volume in ml × ABV percentage ÷ 1,000
For example, one 125 ml serve at 12.5% ABV contains about 1.56 units. Use the exact product strength. The calculator’s displayed unit total describes the full modelled alcohol stock using illustrative strengths; it is not a proposed intake for one person or the group.
The UK Chief Medical Officers advise that, to keep health risks from alcohol low, it is safest not to drink more than 14 units a week on a regular basis and to spread that over three or more days if drinking that much. That weekly guidance is not a party allocation and does not mean 14 units at one event is low risk. For some people and situations, no alcohol is appropriate.
Never convert the stock calculation into a driving rule. GOV.UK says it is impossible to state exactly how many drinks equal the legal limit, the limits differ in Scotland, and alcohol affects people differently. The Highway Code says the best solution when planning to drive is not to drink at all.
Separate public stock, reserve and returns
Do not place every bottle into public service. Give each product a state:
| State | Meaning | Control |
|---|---|---|
| Public | Currently available at the station | Label visible; water and alcohol-free routes equally clear |
| Controlled reserve | Purchased or existing stock not yet released | Named location and refill owner |
| Opened return | Part-used container removed from service | Exact identity, closure and storage instruction retained |
| Unopened return | Sealed stock not required | Keep for lawful later use or return only where retailer terms allow |
| Blocked | Identity, label, contamination or history unresolved | Do not serve |
Use the drinks-station ledger outside Christmas by renaming the event. It gives water, alcohol-free products, glassware, ice, public stock and reserve their own locations and owners.
Then use the party ice plan to keep clean serving ice separate from bottle-chilling ice and prove the freezer or collection route.
Print the exact drinks stock register
| Product ID | Exact product | Volume and ABV | Planned serves | Container yield | Containers | Public | Reserve | Final state |
|---|---|---|---|---|---|---|---|---|
Run three failures before buying: halve the fridge space, remove the assumed spirit bottle and change one guest group to alcohol-free. The plan should reduce or reassign stock, preserve a complete alcohol-free offer and never pressure a guest to explain or compensate.
Questions people ask
How many drinks should I allow per person for a party?
Do not assign consumption to guests. Choose a capped stock amount to make available, separately calculate water and alcohol-free products, then retain unopened reserve. The drinks calculator makes every assumption visible.
How many glasses are in a 750 ml bottle of wine?
A 750 ml bottle contains six full 125 ml measures, four full 175 ml measures with 50 ml remaining, or three full 250 ml measures. Use the exact pour and label rather than assuming every glass is the same.
How do I calculate alcohol units?
Multiply the exact drink volume in millilitres by its ABV percentage, then divide by 1,000. Units describe alcohol content; they do not certify that drinking or driving is safe.
Should party duration increase the alcohol stock?
No. This model deliberately keeps the host-selected alcohol stock cap independent of event length. Its water shopping prompt does use time, but remains an editable planning assumption rather than medical advice.
What should I do with unopened surplus?
Keep it as controlled reserve during the event. Afterwards, retain it for lawful later use or return it only if the retailer’s terms allow. Do not open or serve more merely because it was purchased.
How many drinks can a driver have?
Do not use an online stock planner to answer that. GOV.UK says it is impossible to translate the legal limit into an exact number of drinks and the limits differ in Scotland. The Highway Code says the best solution when planning to drive is not to drink at all.
Sources and checks
- NHS — calculating alcohol units — unit definition and volume-by-strength calculation
- Department of Health and Social Care — UK Chief Medical Officers’ low-risk drinking guidelines — weekly low-risk guidance and single-occasion context; not used as a party quota
- GOV.UK — the drink-drive limit — different Scottish limits and why drinks cannot be converted reliably to a driving threshold
- GOV.UK — Highway Code rules 95 to 96 — driving impairment and the advice not to drink when planning to drive