🥞 Ratio & scaling
The Recipe Scaler
When twice as many people turn up for pancakes, you need to change the recipe the right way, and adding “a bit more of everything” won’t work.
Say you’re making pancakes for eight people instead of four.
It’s tempting to use a bit more of everything.
That’s exactly how the batter goes wrong.
The puzzle
A recipe is a balance of ingredients
What makes fluffy pancakes is flour, milk and egg in a particular balance, and that balance is the recipe. The amounts written down, like 300 g of flour, are that balance at one size.
Your turn. Drag the servings below and you’ll see every ingredient grow together, while the shape bar underneath stays exactly the same.
Serves 4about 12 pancakes
The recipe’s shape. However far you slide, this bar doesn’t change. You multiply every ingredient by the same amount, so the balance between them stays the same.
The trap
More people, so… more of everything?
It’s Saturday morning, and instead of four there are 8 of you. A shortcut lots of people try is “four more people, so add four more to everything”: four more grams, millilitres, eggs and spoons, so every ingredient gets the same extra. Answer before you look. Which batter would you rather eat?
The add-4 batter
flour 304 g (+4)
milk 504 ml (+4)
eggs 6 (+4)
sugar 6 tbsp (+4)
This one comes out rubbery, more like an omelette than a pancake.
The doubled batter
flour 600 g (×2)
milk 1000 ml (×2)
eggs 4 (×2)
sugar 4 tbsp (×2)
It has the same shape at twice the size, so you get proper pancakes.
When you add, every ingredient gets the same extra amount.
When you multiply, every ingredient gets the same treatment, so each one grows in proportion.
The why
Scaling changes the size but keeps the shape
Adding 4 gives every ingredient the same amount, but 4 ml makes almost no difference to 500 ml of milk, while 4 more eggs is a huge change to 2 eggs. Multiplying by 2 gives every ingredient the same treatment, so each one grows in proportion to what it already was. Your turn: try to ruin the batter. With the ratio unlocked, change one ingredient and watch the quality drop. Then lock the ratio and try again.
Size: about 12 pancakes
This is proper batter. The shape matches the recipe exactly.
Doing the sums
Find one serving first
Doubling and halving are easy. The awkward ones are jumps like 6 servings down to 4, which isn’t doubling or halving. What always works is to work out ONE serving first, then multiply up. That turns every awkward jump into two easy steps: divide, then multiply.
The recipe, as written: serves 6
450 g flour · 750 ml milk · 3 eggs
This works for a lot more than pancakes.
You’ll find the same locked ratio everywhere.
Screens, maps and music all keep one ratio while the size changes.
The same idea in other places
Ratios outside the kitchen
Once you know what to look for, you’ll notice lots of things that change size while their ratio stays the same. Tap one to see how.
Each of these keeps a ratio the same while the size changes, just like the batter. Pick one to see how.
A recipe is a balance of ingredients
that you can make at whatever size you need.
You can change the size as much as you like, as long as you multiply everything by the same number.
One more thing
If someone scales a recipe by adding (“four more people, chuck in a bit extra of everything”), ask them how many eggs that puts in, and see if they end up with six for a four-egg job. Then show them how to do it properly: work out one serving first, then multiply up.