How to double a recipe
Not everything doubles, and that is the whole trick.
Multiply the main ingredients by two, but salt and spices by 1.5, yeast by a little less than two, and leave the baking time alone: that follows the tin, not the quantity.
What doubles and what does not
Swipe to see the whole table
| Ingredient | Factor | Why |
|---|---|---|
| Flour, sugar, liquids, fat | x2 | Scale linearly without trouble |
| Meat, vegetables, fruit | x2 | Same |
| Eggs | x2 | If it lands odd, beat one and weigh (50 g per large egg) |
| Salt | x1.5 then taste | Perceived saltiness is not linear |
| Strong spices | x1.5 then taste | Chilli, garlic and clove concentrate |
| Yeast (bread) | x1.5-1.8 | More dough ferments fine on proportionally less |
| Baking powder | x2 | This one is proportional to the batter |
| Alcohol and vinegar | x1.7 | They concentrate more in larger reductions |
| Baking time | unchanged | Follows the depth of the batter, not the amount |
The tin is the real problem
Doubling the ingredients is easy. The hard part is where to put them. Double a cake and bake it in the same tin and the batter rises twice as high, takes far longer to set in the middle and burns on the outside.
There are two fixes: two identical tins (safest, same baking time) or one tin with twice the area. An 8 in round tin has 50.3 sq in; to double it you need about 100 sq in, which is an 11 in round tin.
In the pan and the pot
Doubling a fried base in the same pan does not work the same: the layer is deeper, less water evaporates, and the vegetables end up stewed rather than browned. Use a larger pan, or cook in two batches.
Stews and braises, on the other hand, double well, because the liquid spreads the heat. They just take a little longer to come to the boil.
When not to double
Above about 2.5x, many recipes stop behaving: doughs that a domestic mixer cannot handle, pans that cannot cope, ovens that cannot spread the heat evenly. Two equal batches usually beat one giant one.
Sources and methodology
The non-linear factors (salt, spices, yeast) are widely shared kitchen judgement rather than physical constants: taste and adjust. The tin area calculation is geometry, and it is implemented in the pan size converter.
Frequently asked questions
Do you multiply everything by two when doubling a recipe?
No. Main ingredients yes, but salt and spices are better raised 1.5x and tasted, and bread yeast slightly less than double.
Should I double the baking time?
No. Time follows the depth of the batter and the tin. With two identical tins the time is the same; with one bigger tin, slightly longer.
What tin do I need if I double a cake?
One with twice the area. An 8 in round becomes an 11 in round, or use two 8 in tins and bake them together.
Can I double a recipe with one egg?
Yes: it becomes two eggs. The awkward case is multiplying by 1.5, where you need half an egg: beat one and weigh 25 g.
Can I triple it the same way?
With care. Above 2.5x, check the vessel, the mixer capacity and the timings. Two batches often turn out better.