Ideally? 1500 cartridges per high-use self-defense gun, one for each capable member of the family, and move on. Ideally, you should one day work until you reach between 5,000 and 10,000 cartridges per high-use weapon. It takes time and money to make that happen, so please be patient. Buy an extra box or box of ammo when you can.
A good starting point is to have 500 cartridges, 200 of which should be defensive ammunition, for each weapon in regular use. This is not the ultimate goal, it is the starting point, which means that you must plan to increase your ammunition reserves by thousands. If you have multiple pistols, you should ask yourself which weapon or weapons actually need a ready supply of ammunition. Date your ammunition and store it correctly, and if you need bulk supply, always look for ammunition offers to get the most out of your investment.
You'll see a lot of suggestions out there that you only need 250 rounds of ammunition for pistols at home, 500 at most. This defense rifle uses around 2000 rounds of ammunition minimum, so you need to store a large amount of ammunition for this product. You don't need a lot of ammo (hopefully) to get from point A to point B, and if you're traveling on foot, your ammo count will be dictated by how much you can physically carry. Basically, it is more beneficial to store more ammunition with less caliber than less ammunition with more calibers.
For defense, you must store a minimum of 500 rounds of defensive ammunition for your shotgun, approximately 2000 rounds for your rifle, and finally 1000 rounds for your gun.