Blackberries are one of the lowest-calorie fruits you can eat, but the exact numbers depend on how your serving is measured and how the berries were processed. A fresh blackberry weighs roughly 2.5 grams and delivers about 1 calorie, while canned blackberries in heavy syrup can more than double that for the same weight.
This blackberry calories per ounce calculator converts any serving — ounces, grams, cups, or individual berries — into total calories and a full macronutrient breakdown. Choose between fresh raw, frozen unsweetened, or canned in heavy syrup, and the tool adjusts every value using standard USDA nutrition data. You'll also get a calories-per-ounce benchmark so you can compare serving sizes at a glance.
It's built for calorie tracking, meal prep, and anyone curious about the real nutrition in a bowl of berries.
⚖️ Blackberry Calorie Estimator
Calories per ounce, plus full macros, for any blackberry serving.
📊 Estimated nutrition
| Carbohydrates | — |
| Fiber | — |
| Sugar | — |
| Protein | — |
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How to Use This Tool
Blackberry nutrition varies with how the fruit is processed, so start by picking the form you're eating: fresh raw berries, frozen unsweetened berries, or canned blackberries in heavy syrup. Next, enter your serving size in the number box and choose the matching unit from the dropdown — ounces, grams, cups, or individual berries. If you're not sure which unit to use, the preset buttons quickly load a whole cup, one ounce, or ten berries.
The calculator multiplies your serving by the standard USDA nutrient values for blackberries and returns the total calories, plus the breakdown of carbohydrates, fiber, sugar, and protein. It also shows a per-ounce calorie figure so you can compare serving sizes directly. For the most accurate results, weigh your berries on a kitchen scale — cup volumes can vary by about 10–15% depending on how tightly the berries are packed.
Blackberry Nutrition at a Glance
The table below summarizes the values used in this calculator, based on data from the USDA FoodData Central database. "Per ounce" uses 28.35 g per ounce.
| Form | kcal / 100 g | kcal / oz | Carbs / 100 g | Fiber / 100 g | Sugar / 100 g | Protein / 100 g |
|---|---|---|---|---|---|---|
| Fresh raw | 43 | 12.2 | 9.6 g | 5.3 g | 4.9 g | 1.4 g |
| Frozen, unsweetened | 47 | 13.3 | 11.2 g | 5.0 g | 6.0 g | 1.3 g |
| Canned in heavy syrup | 92 | 26.1 | 23.4 g | 3.6 g | 17.5 g | 1.1 g |
Note that canned blackberries packed in water or juice sit in between fresh and heavy-syrup versions. Most published values for fresh blackberries hover between 40 and 45 kcal per 100 g depending on cultivar and growing conditions.
How the Calories Are Calculated
The calculation runs through three simple steps. First, the serving size is converted to grams using fixed conversions: 1 oz = 28.35 g, 1 cup = 144 g, and 1 average blackberry ≈ 2.5 g. Second, the grams are divided by 100 to get a multiplier. Finally, every nutrient value — calories, carbohydrates, fiber, sugar, and protein — is multiplied by that multiplier. For example, a 50 g serving of fresh blackberries has a multiplier of 0.5, giving 43 × 0.5 = 21.5 kcal.
Calories per ounce is computed the same way: 28.35 g of blackberries × (kcal per 100 g ÷ 100). Fresh blackberries therefore work out to about 12.2 kcal per ounce, which makes them one of the lowest-calorie fruits by weight. For comparison, a banana supplies roughly 25 kcal per ounce, and canned blackberries in syrup nearly double again at 26 kcal per ounce.
Worked Examples
Example 1 — A full cup of fresh berries. One cup weighs about 144 g, so the multiplier is 1.44. Calories: 43 × 1.44 ≈ 62 kcal. Carbs: 9.6 × 1.44 ≈ 13.8 g. Fiber: 5.3 × 1.44 ≈ 7.6 g. A single cup supplies roughly 27% of the daily fiber target of 28 g.
Example 2 — One ounce of frozen unsweetened berries. Frozen values are slightly higher (47 kcal per 100 g), so one ounce gives 47 × 0.2835 ≈ 13.3 kcal — about one calorie more than fresh.
Example 3 — A half-cup of canned berries in heavy syrup. At 72 g per half-cup, the multiplier is 0.72, giving 92 × 0.72 ≈ 66 kcal, with about 12.6 g of sugar. The same half-cup of fresh berries would only contain roughly 4.8 g of sugar.
Factors That Affect Accuracy
The numbers here are averages; your actual berries will differ slightly. Berry size is the biggest variable: a huge cultivated blackberry can weigh 4–5 g, while a wild berry may weigh under 1 g, so weighing by grams is always more reliable than counting berries. Ripeness matters too — sweeter, riper berries can contain slightly more sugar per gram, though the effect on calories is modest, usually within 5%.
Processing also shifts the numbers. Freezing adds ice and can dilute nutrient density slightly, while some frozen products are sweetened with sugar syrup, which raises calories well beyond the unsweetened values shown here. Canned blackberries in heavy syrup absorb a sucrose solution that roughly doubles both calories and carbohydrates. It's also worth remembering that the fiber listed in the breakdown is why blackberries are so filling — a 100 g serving delivers over 5 g of fiber, which helps slow digestion and steady blood sugar. If you'd like to compare with the fiber content of another berry, our blueberry fiber calculator follows the same approach.
Frequently Asked Questions
How many calories are in one blackberry? A fresh blackberry weighs about 2.5 g, so it contains roughly 1 kcal. A cup of about 55–60 berries comes in close to 62 kcal.
How many blackberries are in an ounce? Around 10–12 average berries weigh one ounce (28.35 g). Larger cultivated berries can be closer to 7–8 per ounce, which is why counting berries is less precise than weighing them.
Does "calories per ounce" change if the berries are frozen? Unsweetened frozen berries contain about one more calorie per ounce (13.3 vs 12.2) because they are processed slightly differently and can carry a bit more carbohydrate per gram once icy water weight is accounted for. The difference is small, but it can matter for precise tracking.
Are canned blackberries much worse for a diet? Not necessarily — it depends on the pack. Berries canned in water or their own juice stay close to fresh nutrition, while heavy syrup adds about 49 kcal per 100 g, almost entirely as added sugar. If you're tracking added sweeteners, our honey calories per 100 g calculator gives a sense of how quickly syrup-type sweeteners add up.
Why does this tool show a per-ounce figure if I entered grams? Because calories per ounce is the easiest fixed benchmark for comparing foods; it normalizes away serving-size guesswork. You can use it to eyeball portions: a handful of blackberries about the size of a tennis ball is roughly 4 oz, or about 49 kcal fresh.
For the underlying nutrient data, see the USDA FoodData Central entry for raw blackberries, or read more about the fruit's history and varieties on Wikipedia's blackberry article.