Think of what the army uses.
7 mags 30 rounds a mag is the standard combat load, 6 mags in your pouches one in your gun, that could be easily shot in one engagement. If you are worried about your house being under seige then roughly 6500 round a month for daily action. I keep about 100 per rifle of various bullet types, about one box of each load for small game and bird. I keep two boxes of double ought and 200 for skeet. Then at least 500 at any give time of 22 and pellets.
"To be prepared for war is one of the most effectual means of preserving peace." - General George Washington