Perfect use is correct and ideal use with contraception. It is only achieved when someone follows all instructions, at all times.
Perfect use is usually expressed as a percentage. This percentage is usually higher than the one which shows typical use. Typical use is ordinary use, accounting for human error.
More About Perfect Use
Most contraceptive pills have a perfect use of 99.7%. That means one out of 330 women will become pregnant each year using these pills exactly as directed.
As humans are flawed, achieving perfect use is difficult. It requires understanding how to take medications and contraceptives, then following these instructions each and every time. Taking too little or too much, missing a dose, or taking a dose too late all impact effectiveness. That’s why typical use is usually much lower than perfect use.
The gaps between perfect use and typical use are largest between contraceptives requiring regular use. For example, condoms must be put on correctly before sex every time. People can easily forget the condom in the heat of the moment or put it on incorrectly in their haste. Similarly, people can easily forget a dose of the daily contraceptive pill, especially if their pill must be taken at the same time each day. The perfect use is much closer to typical use for more long-term contraceptive solutions, such as the IUD and implant.
Typical use success rates may seem low in some cases, but for most people the effectiveness of any contraception sits somewhere between perfect and typical use. Most people have a few slip-ups, but use their contraceptives fairly reliably.