Fennel is a crisp, mildly anise-flavored vegetable that fits easily into low-calorie meals. Raw fennel bulb contains only about 31 calories per 100 grams, which works out to roughly 0.31 calories per gram. Because it is rich in water and fiber, it adds bulk and crunch without blowing your daily calorie budget.
This calculator lets you convert any amount of fennel — whole bulbs, sliced cups, or even fennel seeds — into calories. Select the form of fennel you are using, enter the weight in grams, ounces, or pounds, and the tool will calculate total calories, calories per gram, and the reference value per 100 g.
It is designed for meal planners, home cooks, and anyone tracking calories or macronutrients. Use it to build accurate portions for salads, soups, roasting trays, or seed-based spice blends.
🥬 1. Choose Fennel Form
⚖️ 2. Enter Amount
Step-by-Step Guide
Start by choosing the fennel form that matches what you are about to eat. Raw fennel bulb is the most common choice for salads, crudités, and roasting; cooked bulb works when you are weighing leftovers after boiling or steaming; fennel seeds are best selected for recipes where whole or ground seeds are the main ingredient.
Next, enter the amount. You can type a weight in grams, ounces, or pounds, or click one of the preset chips. The calculator converts ounces and pounds to grams automatically using 1 oz = 28.3495 g and 1 lb = 453.592 g.
Press Calculate Calories to see total kcal, the selected form, calorie density per gram, and the calculation step. The result panel also shows the reference value per 100 g so you can compare fennel with other vegetables on a per-weight basis.
How the Calculation Works
Calories scale linearly with weight, so the formula is simple: total kcal = (weight in grams ÷ 100) × kcal per 100 g. For raw fennel bulb, the reference value is about 31 kcal per 100 g, which equals about 0.31 kcal per gram. A 150 g serving therefore supplies (150 ÷ 100) × 31 = 46.5 kcal.
Reference values in this calculator are based on the USDA FoodData Central database (available at fdc.nal.usda.gov). As with any whole food, small variations in variety, maturity, and water content can cause slight differences between one fennel bulb and another. If you are tracking macros, the same weight proportion applies to protein, carbohydrates, and fiber, but this tool focuses on energy in kilocalories.
Worked Examples
- 150 g raw fennel bulb: (150 ÷ 100) × 31 = 46.5 kcal → about 0.31 kcal/g.
- 100 g cooked fennel bulb: (100 ÷ 100) × 27 = 27 kcal → about 0.27 kcal/g.
- 6 g fennel seeds (about 1 tbsp): (6 ÷ 100) × 345 = 20.7 kcal → about 3.45 kcal/g.
Tips & Best Practices
For the most accurate tracking, weigh fennel before cooking. Cooking drives off water, so if you weigh after cooking and use the raw value, you will undercount the calories. Use the raw bulb setting for raw weight and the cooked bulb setting only when the portion is already cooked and no oil, butter, or sauce has been added.
Remember that roasted or sautéed fennel absorbs oil. A tablespoon of olive oil adds about 120 kcal, which can quickly exceed the calories in the fennel itself. If you prepare fennel with oil, log the oil separately.
Use a digital kitchen scale rather than volume cups when you can. Chopping method changes how tightly fennel fits into a measuring cup, so 1 cup of finely sliced fennel can weigh noticeably more or less than 1 cup of coarsely chopped fennel.
Fennel seeds are much more calorie-dense because they are dry and concentrated. Weigh seeds in grams or small spoonfuls rather than estimating by eye.
Fennel Nutrition Reference Table
| Form | kcal / 100 g | kcal / gram | Notes |
|---|---|---|---|
| Raw fennel bulb | 31 | 0.31 | High water content, low calorie density |
| Cooked fennel bulb | 27 | 0.27 | Values vary slightly with cooking method |
| Fennel seeds | 345 | 3.45 | Dry, concentrated, high in fiber and oils |
Frequently Asked Questions
Is fennel a good choice for a low-calorie diet? Yes. A 100 g portion of raw fennel bulb supplies only about 31 kcal while providing a satisfying crunch and about 3 g of fiber. It can replace higher-calorie snacks or add volume to meals without changing the calorie budget much.
Should I weigh fennel raw or cooked? Weigh raw before cooking when possible and select the raw bulb option, because the calories in the raw fennel do not change when it cooks — only the water content changes. If you are logging a portion that has already been cooked, use the cooked bulb option and be sure no fat or sauce was added.
Why do fennel seeds have so many more calories than the bulb? Seeds are nearly dry, so water is a much smaller proportion of their weight. Fennel seeds also contain natural oils and a dense mix of macronutrients. A small sprinkle adds very few calories, but a handful can add meaningful calories.
Can I use this for fennel tea? Plain fennel tea made by steeping seeds in hot water is effectively zero calories if no sweetener, milk, or cream is added, because the seeds themselves are not consumed in significant amounts.
How does fennel compare with other low-calorie vegetables? Raw fennel is in a similar range to cabbage, spinach, and celery when measured per gram. If you log several green vegetables, you can use the same per-gram approach with the spinach calories per gram calculator or the cabbage calories per gram calculator to keep your daily totals consistent.