With homemade dog food, you have to be aware that portioning may differ from canned and dry food. One of the easiest ways to portion your food is to consult with your veterinarian. There are also many other shortcuts that you can take to figure out portioning.
One great dog food provider is Merrick -- "organic" enough for your fur babies that you can't hate them! One reason why I started to make my own dog food, however, is because Merrick is so expensive. Most of Merrick is grain-free as well, so you can use their dog food portion calculator to determine the amount of food that you can use for your dogs if you are not adding rice, oats or grains. Merrick goes by can size -- each can is about 13 ounces. That is about 1 and 2/3 cups of food. Remember to compare your food to Merrick's to see the consistency (dense, blended vs. chunky in gravy). That will matter greatly for the calories along with the ingredients!
If you are adding rice, oats and grains to your homemade dog food, you need to use a different calculator. Searching around for a high quality canned dog food, I found Nutro -- and I often feed my dogs the kibble from them. If you look at their many types of canned dog food, you should be able to match one close to what you are making. You can then check the feeding guidlines and go from there! Their can size is similar to Merrick and each can is equal to about 1 and 2/3 cups of food!
When combining the homemade dog food and kibble, always use a high quality kibble. Grain-free or not, make sure you are picking a dog food with healthy ingredients. I often lower my dogs' canned food recommendation by about 1/4 of a cup and mix only about a handful or so of the kibble with the soft food to add some crunch. Note that they are chihuahuas! You may have to play around with your own mix -- some even get dental dog food to mix to sneak in some health benefits!