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ELI5 Yahaaa

Not everything scales

How Do You Double a Recipe?

Ingredients double neatly. Pans, times and temperatures do not.

Ingredients Double them allTime and heat Leave them nearly alone
Scaling a recipe is two different sums pretending to be one.

  1. Step 1 of 5

    Ingredients scale in proportion.

    1 Every amount2 × 23 The ratios areunchanged

    Every amount is multiplied by the same number. Two hundred grams becomes four hundred, one egg becomes two, and the ratios stay put.

  2. Step 2 of 5

    The ratio is what actually matters.

    Both doubled The same doughOne doubled?A different recipeentirely

    A recipe is really a set of proportions. Doubling both flour and water keeps the dough identical; doubling only one ruins it.

  3. Step 3 of 5

    Volume grows faster than surface.

    Double the volume Nothing like double thesurface

    Twice the mixture in the same tin is twice as deep, but the top and sides are barely bigger. Heat has much further to travel to the middle.

  4. Step 4 of 5

    So the time goes up and the heat goes down.

    Ingredients× 2 exactlyCooking timeup by about halfTemperaturedown a little,if at all

    A doubled cake needs longer at a slightly lower temperature, or the outside burns while the centre is still raw.

  5. Step 5 of 5

    Some things refuse to scale at all.

    Flour and water Scale straight upSalt and spice Scale up, but less thandouble

    Salt, spice and raising agents often need less than double, and a pan can only hold so much before it stops frying and starts stewing.

    Halving is the same problem backwards, which is why half an egg is the most annoying quantity in cooking.

The short version

Doubling a recipe multiplies the ingredients but not the time, heat, or pan, because volume grows faster than surface.

Try it yourself

Measure a cake tin's width and depth. Doubling the mixture in the same tin doubles only the depth.

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