How do you know if a peach is perfect? It's not too difficult to determine if you use your senses. There are three things to notice when looking for a peach that's as ripe as you want it to be: color, texture and smell. Checking to see if a peach is perfect should take only five seconds, a scant few moments that will be worth it when you bite into a delicious, ripe, juicy peach.
Although there are hundreds of varieties of peaches, most of the ones you'll find in the grocery store will be yellow or white peaches. The farmers market may have many other varieties, and you can talk to the farmers about them and their ripeness. But, when you're in the store, looking at the color is the first step.
For both a yellow and a white peach, the stripes under the darker color of the peach should be fully yellow or white (which is actually more cream than white). If those stripes are still green, the peach was picked before it was fully mature. Don't choose that peach. If the color is right, move on to the next step.
Give the peach a gentle — very gentle — full-handed squeeze to test how firm it is. If it's very hard, it won't be ready to eat for several days. It will however continue to ripen after it's been picked so if you want to buy peaches to eat in a few days, you'll want them to be on the firm side.
If the peach has some give, like a tennis ball, it's ripe and ready to eat immediately or in the next day or two. If it's mushy, it's past its prime. That doesn't mean it isn't useful. Mushy peaches can be used for making peach jam, and you can often find them at a discount at the farmers market.
The last thing to check for is smell. A ripe peach should be aromatic. The firmer peaches will be less aromatic but will still smell like a peach. In a few days, their aroma will increase. If the peach doesn't smell at all, or if it smells funky or off, move on to a different peach.