The vanMelzen Sum
What the Pythagorean theorem is to the triangle, the vanMelzen Sum is to the party. One formula, infallible and written in the stars, that tells you how many crates of beer to buy. For a birthday, a party or simply a good night together.
Or compact, with n = number of beer drinkers:
Calculate, and always round up to an even number of crates. You can't walk on one leg.
Exception: for up to two beer drinkers, simply buy one crate per beer drinker.
— vanMelzen. Written in the stars.
Why the Sum works
No two beer drinkers are the same. One sticks to three or four bottles, another will happily knock back eighteen to twenty in an evening. There is always a last sip left in a bottle somewhere, and one is bound to get knocked over or dropped.
On top of that, an average party lasts four to six hours. During that time people slowly build up, reach a peak, and after that the drinking often tails off again.
The vanMelzen Sum takes all of that into account, in one simple formula distilled from years of experience. Alcohol mathematician Van Melzen has already answered countless parties with it.
Could the Sum be more complex? Certainly. Does it need to be? No.
And above all: you never want to be the host who has to announce that the beer has run out.
Did you apply the Sum?
The Sum is never wrong, but we'd love to hear how the party went.
Frequently asked questions
What is the vanMelzen Sum?
The ultimate formula for how many crates of beer to buy: crates = 2 · ⌈(beer drinkers / 2 + 2) / 2⌉. Divide the number of beer drinkers by two, add two, and round up to an even number of crates. For up to two beer drinkers, simply buy one crate per beer drinker. As Pythagoras closed the triangle, the Sum closes the party.
Does the Sum account for heavy drinkers?
Yes. One beer drinker has three or four bottles, another eighteen to twenty; bottles get left half-finished and one gets knocked over now and then. The vanMelzen Sum covers all of that in one simple formula, distilled from years of experience, so the beer never runs out.
How long a party is the Sum meant for?
For an average party of four to six hours. During that time people slowly build up, reach a peak and then drink less again; the vanMelzen Sum takes that whole course of the evening into account.
Is the Sum always right?
Yes. The vanMelzen Sum is written in the stars: follow it and you'll never run dry. If there's some left over, you've simply stocked up for the next party.
Why always an even number of crates?
Because you can't walk on one leg. And when beer is on offer in the Netherlands, it's often "second crate half price" or "second crate 25% off": with an even number you always get the full discount. Mathematically it's the 2 · at the front: from three beer drinkers the answer is always 4, 6, 8 and so on. Only for up to two beer drinkers do you simply buy one per drinker.
How many crates of beer do I need for 20 people?
According to the vanMelzen Sum, 12 crates for 20 beer drinkers: (20 / 2 + 2) / 2 = 6, and 2 · 6 = 12.
How many crates of beer do I need for 50 people?
According to the vanMelzen Sum, 28 crates for 50 beer drinkers: (50 / 2 + 2) / 2 = 13.5, rounded up to 14, and 2 · 14 = 28.
And will those crates fit in my car?
Find out on hoeveelkratten.nl: enter your Dutch licence plate and see how many crates fit in your boot, and whether you'll need more than one trip.