I am often amazed that many shooters only have the one or two magazines that came with their guns. Not realizing that they will not have time to reload outside of practice at the firing range. Spare magazines are what you need to carry spare ammunition at the ready. This applies to self-defense, competition or the zombie apocalypse.
The big question is how many spare magazines do you need. The generic answer is enough spares to cover loss and/or damage with enough rounds to cover your needs. This doesn’t tell you much.
I want to introduce what I call the 3/5 Rule for magazines. You need a minimum of 3 magazines, and 5 magazines is highly recommended.
Three magazines will allow you to have one in your gun, and two spares. This is enough to allow for lost or broken magazines and enough ammunition capacity to handle most situations.
The only situation you may have problems with is competition. Three magazines may not have enough capacity for some competitions, especially if you have single stack magazines with a capacity less then 10 rounds.
I personally recommend five magazines. This will definitely give you enough spares to cover loss or damage and enough capacity for any need. Even a zombie apocalypse. I also see 5 magazines being a lifetime supply for the average shooter.
This same rule can also be applied to rifles as well, especially with military pattern rifles such as the AR-15. The purpose of these rifles is defeated without spare magazines. A good lever gun is more useful if you don’t have spare magazines.
I would even buy a few more for rifles. Three to five magazines minimum of 20-30 round capacity for self defense, competition and a zombie apocalypse, 2 to 4 ten round magazines for range work and 1 or 2 five round magazines if you hunt with your semi-auto rifle. This gives you six to eleven magazines for your rifle.
Spare magazines may be expensive, but a needed accessory for your firearm to work properly. They should be considered a semi-disposable item. Do take care of them. They will give you years of good service. But be aware they wear out, break or can be lost. Definitely buy spares. One or two is not enough.
Three to Five magazines should be enough for the average shooter.
One last comment, a quality magazine carrier is worth the money. It is easier to carry your spare magazines and will keep dirt and pocket lint out them, which may cause malfunctions.
Many manufacturers are now including a cheap plastic magazine carrier. They are cheap in both contexts of the term. Buy something better as soon as you can.
Hope this information is useful to you and clears up any questions on how many magazines you need.