Do you ever watch an episode of Bake-Off and boggle when the contestants make jam — in a frying pan? Just because their recipe calls for a small amount of jam for a layer of a cake? How do they do that? Jam must be made in huge quantities, in a gargantuan pot, from flats of berries or massive big baskets of peaches… doesn’t it?

And what happens if you get your fruit home and there’s not enough to make Grandma’s beloved recipe because it calls for 11 pounds of peaches and you’ve only got 7? The recipe will get messed up and jam is already a hot, scary, time-consuming task. Better to just buy a jar and forget about making your own, right?

Hang on, ya’ll, I’m about to rock your world.

See, the quantities in recipes are really just proportions. In recipes with only a few ingredients, you can actually break your quantities down to a ratio, like with cocktails. If a martini recipe calls for 2 parts gin to 1 part vermouth (yes, that’s too much vermouth, I’m using it as an example. And no, martinis are never made with vodka!), you can make any quantity of martini from 1 glass to a pitcher to a bathtub full, just by using the same size of measure for both ingredients.

Well, you can do the same for jam.

By reducing a jam recipe to a ratio of parts fruit to parts sugar, by weight, then you have a fairly infallible jam recipe that can be made in quantities from a single jar to multiple dozens, based totally on the amount of fruit you’re starting with.

This is awesome if you live in a small household that can’t possibly work through dozens of jars each year before it’s time to make jam again. (Or before it all turns brown and scary, even though you’ve stored it somewhere dark and cool.) I typically now only make 2 or 3 jars of any type of jam at a time because I use the ratio method and buy small amounts of fruit.

I came up with these figures by surveying the top 5 or 6 most popular online recipes for each type of jam and breaking the recipes down into a standard unit of weight, then translating those weights into a ratio of fruit to sugar, averaging the ratios to get a working ratio for each fruit.

(I’ve not included marmalade or currant jellies here because they typically include water and the ratios are different, plus there are extra steps that can affect pectin quantities.)

All you need to make a well-balanced jam is a scale. (Well, pots and jars and such, too, but you get the jist…) Imperial and metric are both fine, but keep to one or the other and measure ingredients by weight. Then mix your prepared fruit (stone fruit should be pitted, for instance, strawberries should be hulled) and sugar to the following ratios:

  • Cherry (sour): 1 part fruit to 1 part sugar
  • Strawberry: 2 parts fruit to 1 part sugar
  • Raspberry: 2 parts fruit to 1 part sugar
  • Sweet Plum (ie. Damson): 2 parts fruit to 1 part sugar
  • Peach: 2 parts fruit to 1 part sugar
  • Apricot: 2 parts fruit to 1.5 parts sugar (or 4:3, if that’s easier)
  • Mango: 2 parts fruit to 1 part sugar
  • Blueberry: 4 parts fruit to 1 part sugar (You could go 3:1 here and it would be fine)
  • Quince: 1 part fruit to 1 part sugar
  • Mixed berry/bumbleberry: 2 parts fruit to 1 part sugar
  • Mixed stone fruit (peaches, apricots, yellow plums): 2 parts fruit to 1.5 parts sugar

As a guide, fruit that you can eat out of hand is usually a 2:1 ratio, anything tart or sour (cherries, quince, some apricots) needs 1:1.

If you use those ratios, add a squeeze of lemon proportional to the amount of fruit and sugar (a squeeze for a small batch versus half a lemon for a big pot, for instance) and then any other additional flavourings you like to enhance the jam.

This ratio system does NOT require added pectin. Jams will cook up and set at this ratio without boxed pectin. The lemon and sugar, plus cooking, is what is going to make your jam set. Do not omit the lemon juice.

Note that while you can safely increase the sugar amount if you find these ratios too tart, do not decrease the sugar amount as that will throw off the amount of natural pectin and could leave you with runny jam. As always, cook to the appropriate temperature and do a wrinkle test to assure the jam is cooked enough to set.

So go off and make some jam, in any quantity that suits you.