It's annoying to realise you don't have some ingredient needed for your dish after you have started cooking. eReplacementParts made a handy infographic of food substitutes for common ingredients, which you can print out and stick to your refrigerator.
The good part about this infographic is that it not only tells you the item you can substitute, but the amount required too. For example, it's fairly well-known that you can replace lemon juice in many recipes with apple cider vinegar. However, it's not a 1:1 ratio. If the recipe calls for 1tsp for lemon juice, you need to substitute it with 1/4th tsp of apple cider vinegar.
It's not a comprehensive guide and misses out on some of the tricks we have covered in the past, like using butter and milk instead of heavy cream. Still, it's got a lot of common items covered.
Check out the full infographic and if you find it useful, head over to the link below for a larger-sized version to print out.
This for That: A Guide to Cooking And Baking Substitutions | eReplacementParts via WonderHowTo