A lot of conversions can be found in the back of a popular cook books, like The Joy of Cooking. I have a small notecard tucked into my own recipe book with the most common conversions & substitutions I use while cooking, so I don't have to memorize them all.
Helpful Hints:
When baking cupcakes or muffins, bake at 325 F for 18 minutes.
Lower the oven 25 degrees when baking in a glass dish.
For baking in a convection oven, lower the oven 25 degrees and decrease the baking time.
Let the butter & eggs sit out at room temperature for cookies & cakes. Butter should be cold for pastry.
Always sift dry ingredients. Whenever possible, use the appropriate flour (pastry/cake, bread, or all-purpose).
Converting from US Standard to Metric:
1 stick of butter, 8 T, 1/2 c = 113 g
5 1/3 T butter, 1/3 c = 75 g
450 F ~ 230 C
425 F ~ 220 C
400 F ~ 205 C
375 F ~ 190 C
350 F ~ 175 C
Many times I make recipes when I don't have all the ingredients by simple substituting something I do have for the missing ingredient. You usually can't tell the difference.
Substitutions:
I experimented with vegan cooking for a bit, so I tried out some egg substitutes. Everyone always suggests to just buy the vegan egg replacer that comes in a box, but I'd rather use standard ingredients. There are many more egg substitutes out there, these are just the ones that worked for me. This is also great to know if you want to bake something & don't have any eggs left! I guarantee there is something in your kitchen to substitute for the egg.
Eggs have two functions in recipes: leavening & binding. They are used in dense foods, like cookies & brownies, and lighter foods, like breads, cakes, & muffins.
For cookies & brownies:
If you're replacing an egg for binding then 1 egg = 1/2 banana (or other fruit), 1/4 c apple sauce, 1/4 c silken tofu
If you're replacing an egg for leavening then 1 egg = 2 T water + 1 T oil + 2 t baking powder, or any of the above + 2 t baking powder
For breads & cakes:
1 egg = 2 t baking powder & 1/2 c soy yogurt (the yogurt will add moisture & denseness)
1 egg = 1 t yeast in 1/4 c water
For cakes & muffins:
1 egg = 1 T vinegar + 1 t baking soda
*do not replace more than 3 eggs. For angel food cakes or others that call for many eggs, I suggest buying the vegan egg replacer.
1 c cow's milk = 1 c almond milk, soy milk, etc.
1 c buttermilk/sour milk = 1 c milk + 1 T lemon juice or vinegar/2 t cream of tartar (let stand 10 mins) = 2/3 c plain yogurt + 1/3 c milk = 1 c plain low-fat yogurt = 1 c sour cream
1 c banana = 1 c applesauce
1 c all-purpose flour = 1 c whole wheat, or 1 c oat flour, or 1 c gluten free flour.
1 c cake flour = 1 short cup white flour
1 square unsweetened baking chocolate = 3 T cocoa powder + 1 T butter
1 c butter = 1 c vegetable/canola oil
