Guest Post!! Holiday Favorites from Robin of Bird on a Cake

If there’s one thing I’ve learned over years of hosting everything from kids’ birthdays to backyard 50ths, it’s this: running out of drinks will haunt you forever, and overbuying means staring at a fridge full of lukewarm mixers for the next six months. Neither is fun. So I finally sat down—cup of tea in hand, Aloo asleep at my feet—and pulled together the no-nonsense drinks calculator I wish I’d had years ago.

This guide is written for the woman who does it all: planning, prepping, pouring, smiling through the chaos… while trying to make the whole thing feel effortless. Whether you’re throwing a birthday bash, retirement party, holiday get-together, or the classic “just because we need a night with the girls,” this calculator will take the guesswork out.

Let’s keep it simple, doable, and totally stress-free.

The 3-Rule Party Drink Calculator
(You can literally plan your whole bar with this.)

1. Assume 2 drinks per guest in the first hour
   People arrive thirsty. They mingle. They top up.
2. Then 1 drink per guest per hour after that
   This is where the pace naturally slows.
3. Multiply by your party length
   Done. No apps, no math headaches, no complicated charts.

Quick Cheat Sheet: What to Buy for 10, 20, 30, or 50 Guests

For a 3-hour party:

10 Guests
– Wine: 3–4 bottles
– Beer/Cider: 12–18 bottles
– Spirits: 1 bottle vodka or gin + 2 mixers
– Soft drinks: 4–6 litres
– Water: 4–6 litres

20 Guests
– Wine: 6–8 bottles
– Beer/Cider: 24–36 bottles
– Spirits: 2 bottles + 4–5 mixers
– Soft drinks: 8–10 litres
– Water: 10 litres

30 Guests
– Wine: 10–12 bottles
– Beer/Cider: 36–48 bottles
– Spirits: 3 bottles + 6–8 mixers
– Soft drinks: 12–14 litres
– Water: 12–16 litres

50 Guests
– Wine: 15–20 bottles
– Beer/Cider: 60–80 bottles
– Spirits: 4–5 bottles + 10 mixers
– Soft drinks: 20 litres
– Water: 20–25 litres

If You’re Serving Mostly Wine
Go 60% white, 40% red unless it’s winter, then flip it.

For afternoon parties, rosé counts as a white—buy a couple bottles because someone always wants it.

If You’re Serving Cocktails
Stick to one signature cocktail plus a basic spirit (vodka or gin) with soda or tonic. Trust me, nobody needs a full bar unless you’re running a hotel.

For a 20-guest gathering:
– 2–3 bottles liquor for the signature cocktail
– Enough mixer to match (lemonade, juice, ginger beer, etc.)
– Garnishes: limes, lemons, mint, berries
– 2kg ice for shaking and topping

If You’re Serving Beer Drinkers
Plan for 1.5 bottles per person per hour if beer is the star of the show.
Beer-focused gatherings are thirstier gatherings. It’s science.

Don’t Forget Ice — Seriously
Ice is the one thing everyone underbuys. You need more than you think.

Ice Guide:
– Small gathering (10 guests): 3–4 kg
– Medium (20–30): 6–8 kg
– Large (50): 10–12 kg

If it’s summer, add another 20%.

Essential Mixers That Always Get Used
– Soda water
– Tonic
– Lemonade
– Cola
– Cranberry juice
– Orange juice
– Ginger beer
– Fresh citrus (honestly the unsung hero of any bar)

Keep it simple; nobody needs lychee cordial at a 60th birthday unless you really love lychee.

Water, Water, Water
Your future self will thank you. Hydrated guests dance more, complain less, and recover beautifully.

Plan for 1 litre per person minimum.
More if it’s hot, outdoors, or includes dancing (my favourite cardio).

When in Doubt, Buy a Little Extra
You can always send guests home with leftover cans and bottles. It doubles as a quiet nudge to clean your fridge.

The only time I truly regret buying extra is when Aloo gets into the recycling bin the next day and has the time of his life spreading cans around the backyard.

Hosting Made Easier
Once you’ve used this drinks calculator once or twice, it becomes instinctive. And honestly, when you’ve got the drinks sorted, the rest of the party feels lighter. No frantic runs to the bottle shop, no panic when the rosé runs out. You get to relax, enjoy, and actually be present at your own gathering—what a concept.