All Fruit & produce

A ripe peach has a warm cream or yellow background colour, a sweet aroma and a little give near the shoulders. Red blush is not the deciding factor. A peach can be bright red on the sunny side and still be hard or immature.

SignalRipe or nearly ripeNot ready or past it
Background colourCream, gold or warm yellow under the blushGreen around the stem and shoulders
FeelSlight give under gentle palm pressureRock-hard, deeply soft, wrinkled or bruised
AromaClearly fragrant at the stem endOdourless or fermented
Two Buttons meme about squeezing a peach versus checking its colour and allowing time to ripen

Ignore the blush first

Red blush is driven mostly by sun exposure. Turn the peach over and look for its underlying colour, especially near the stem cavity. A warm yellow or cream background is a better sign than redness. A strong green cast means the fruit may be immature, not merely firm.

Use your whole hand, not one finger

Pressing with one fingertip makes a bruise efficiently. Cradle the peach in your palm and apply gentle pressure near the shoulders. A peach for today should yield slightly. One for tomorrow can be firmer if its colour and aroma are promising.

Ripen on the counter, then refrigerate

Leave firm peaches at room temperature in a single layer until they smell fragrant and give slightly. Once ripe, refrigeration buys a little time. Peaches are climacteric fruit, so they can soften and develop aroma after harvest, but an immature peach cannot recover quality it missed on the tree.

Compare the snack nutrition in peaches vs. apples, or read the counter-ripening guide for the broader ethylene rule.

Sources

University of Florida IFAS explains climacteric stone-fruit ripening and why color, aroma and careful handling matter.