Cucumbers are one of the lowest-calorie vegetables you can put on a plate, but a single cucumber slice is not automatically zero calorie. A 100 g serving of raw cucumber with peel supplies roughly 15 kcal, so the energy in each slice really depends on how wide the cucumber is and how thick you cut it. This calculator uses either slice dimensions or an actual slice weight to give you a practical, food-diary-ready estimate.
Use the size method when you do not have a scale: enter the cucumber diameter and slice thickness, and the tool estimates the slice volume and weight using a typical cucumber density of about 0.7 g per cm³. Use the weight method when you want precision from a kitchen scale. Both approaches apply the USDA calorie value of 15 kcal per 100 g of raw cucumber with peel.
This tool is handy for meal prep, low-calorie snacking, salad recipes, and anyone tracking calories or macros. It also calculates totals for multiple slices, so you can log a full garnish, sandwich filling, or snack plate in seconds.
🥒 Cucumber Calories Per Slice
Estimate calories in a single slice or a whole bowl — by cucumber size or actual slice weight.
📊 Results
How to Use This Calculator
Cucumber slices are tiny, irregular, and mostly water, so trying to eyeball their calories is easy to get wrong. This calculator gives you two ways to get a reliable estimate. If you have a kitchen scale, use the measured slice weight method: cut a slice, weigh it, and enter that number along with how many slices you are eating. If you do not have a scale, use the slice size method and enter the cucumber diameter and slice thickness; the tool estimates the weight from the slice volume.
- Choose a calculation method from the dropdown.
- Enter the cucumber diameter (cm) and slice thickness (mm), or enter the weight of one slice (g).
- Enter the number of slices you plan to eat.
- Press Calculate calories to see per-slice calories, total calories, and estimated slice weight.
The Math Behind the Estimate
The calorie base for this calculator is the USDA value for raw cucumber with peel: about 15 kcal per 100 g, which works out to 0.15 kcal per gram. For the size method, the tool treats a slice as a short cylinder and estimates its volume using the formula for the volume of a cylinder:
It then multiplies that volume by a typical cucumber density of about 0.70 g/cm³ to estimate slice weight. Finally, the estimated weight is multiplied by 0.15 kcal/g to get calories per slice, and that value is multiplied by the number of slices to get the total. Because cucumbers are roughly 95% water, the numbers are small, but they still matter when you are logging every item in a salad, sandwich, or snack plate. The density figure is a practical average; a very fresh, water-packed cucumber may be closer to 0.75 g/cm³, while an older, slightly shriveled one may be closer to 0.60 g/cm³. This is why the measured weight method is the best choice when accuracy matters. You can check the official reference values in USDA FoodData Central.
Worked Examples
Example 1: Thin slices, no scale. You cut a cucumber with a diameter of 4 cm into 3 mm slices. The radius is 2 cm and the thickness is 0.3 cm, so the volume of one slice is π × 2² × 0.3 ≈ 3.77 cm³. At 0.70 g/cm³, each slice weighs about 2.64 g. At 0.15 kcal/g, one slice provides about 0.40 kcal. A dozen thin slices would give about 4.7 kcal total.
Example 2: Weighed slices. You weigh one slice and it comes to 8 g. Calories per slice = 8 × 0.15 = 1.2 kcal. If you add five such slices to a wrap, that is about 6 kcal total. Compare that with a tablespoon of ranch dressing at roughly 60 kcal, and you can see why cucumber is a favorite low-calorie filler.
These examples also show why thickness matters: doubling thickness from 3 mm to 6 mm roughly doubles the calories per slice because the slice volume doubles.
Calorie Reference for Common Cucumber Portions
The values below come from USDA portion data and are useful for quick mental estimates before you use the calculator.
| Portion | Approx. weight | Calories |
|---|---|---|
| Raw cucumber with peel, 100 g | 100 g | 15 kcal |
| 1 cup sliced with peel | 104 g | 16 kcal |
| 1 medium cucumber (8 1/4 in) | 301 g | 45 kcal |
| 1 medium 6 mm slice, 4.5 cm diameter | about 7 g | about 1 kcal |
Tips for Accurate Calorie Tracking
- Weigh when possible. A 1 g error on a cucumber slice is only 0.15 kcal, but errors add up across a meal and across the day. The scale method removes density guesswork.
- Include the peel. The calculator assumes raw cucumber with peel, which is how most people slice it. Peeled cucumber is closer to 12 kcal per 100 g, so if you always peel your cucumber, multiply the result by 0.8.
- Be consistent with thickness. If you use a mandoline or a sharp knife, try to keep slices at a regular 3–6 mm so your per-slice estimate stays stable.
- Log the whole vegetable. A whole medium cucumber is about 45 kcal, so even a large sliced cucumber is far less energy-dense than cheese, nuts, or dressings on the same plate.
- Check prepared cucumber products. Flavored cucumber slices, cucumber salads, or pickled cucumbers can contain added sugar, oil, or sodium, so use a nutrition label or a separate recipe calculator in those cases.
Frequently Asked Questions
Are cucumbers really a negative-calorie food? No. Cucumbers contain about 15 kcal per 100 g, which is very low, but still more than zero. The idea of a negative-calorie food is a myth; the energy cost of chewing and digesting cucumber is tiny compared with the calories it provides, though the calories are negligible in the context of a normal meal.
Why does a 6 mm slice from one cucumber weigh more than the same slice from another? Cucumber density and diameter vary by variety, ripeness, and water content. English cucumbers are long and slender, pickling cucumbers are short and narrow, and slicing cucumbers are thicker. That is why the calculator includes a diameter input for the size method.
Should I count cucumber calories in a food diary? It depends on your goal. If you are tracking calories strictly, yes, because small amounts add up across the day. If you are loosely mindful, the ~1 kcal per slice is usually not worth stressing over. What matters is the added oils, dressings, and dips you pair with the cucumber.