The amount of sugar in fruits varies, from about a teaspoon in a 3.5-ounce serving of tart berries, to about 2.5 teaspoons for a 3.5-ounce serving of apple, to 4 teaspoons for a 3.5-ounce serving of grapes. Many fruits popular in the United States have a moderate amount of sugar.
Tart berries, such as raspberries, strawberries and blackberries, have less sugar than many other fruits at 4.42, 4.66 and 4.88 grams of sugar per 3.5274-ounce (100-gram) serving respectively. Grapefruit, another tart fruit, typically has about 6.89 grams of sugar per 100 grams.
Melons have small amounts of sugar compared to some fruits. A typical 100-gram serving of watermelon has 6.20 grams of sugar. Honeydew melon registers a bit more with 8.12 grams per 100-gram serving.
Among popular fruits in the United States, apples have 10.39 grams of sugar per 100-gram serving, peaches have 8.39 grams per 100, and pears have 9.80 grams. Plums are close to pears at 9.92 grams of sugar per 100-gram serving. Blueberries have more sugar than tarter berries at 9.96 grams per 100-gram serving.
At the high end are grapes, figs and pomegranates, which have 16.25, 16.26 and 16.57 grams of sugar per 100-gram serving, respectively.
There are 28.3495 grams in 1 ounce. A teaspoon is about 4.2 grams.