Just measure real well, door size and what could theoretically fit into your stove. Now mix in with your stacks enough of those size pieces to be night logs. I keep out a good selection of gnarly hard to split big chunks for that purpose. Plus...late night pit stops....when it is cold enough, I'll keep it going one way or the other, this time of year, meh, I just relight it if I need to in the morning, house doesn't have to be warm at night. Takes a lot more wood anyway to do that. Fall is real hit or miss here, few days cool enough to burn, then back to sweat city. This will go on until December. It's goofy, I've picked ripe tomatoes on Christmas day here, and once a few years ago we had six inches of snow on Christmas day. Just learn your stove and stack a variety of species and sizes, then you can adjust for what heat and duration you need.