How Many Calories in Rhubarb? Nutrition Facts & Macros
100 grams of rhubarb has 21 calories
Protein 0.9g · Carbs 4.5g · Fat 0.2g
Rhubarb (Rheum rhabarbarum) is a vegetable botanically, but classified as a fruit culinary. With just 21 calories per 100g, it is one of the lowest-calorie foods available — even lower than celery. Its signature tart flavor comes from oxalic acid. Rhubarb is exceptionally high in calcium (86mg) and vitamin K (29µg). The stalks are edible; the leaves are toxic. Peak season is April through August. One cup of diced rhubarb (122g) has only 26 calories.
88 kJ · per 100g · Water: 93.6 g
Calorie Calculator: Rhubarb
100 g Rhubarb contains 21 kcal
Calories by Portion Size
| Portion | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| 1 cup diced (122g) | 26 kcal | 1.1g | 5.5g | 0.2g |
| 1 stalk (51g) | 11 kcal | 0.5g | 2.3g | 0.1g |
| 100 grams | 21 kcal | 0.9g | 4.5g | 0.2g |
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Rhubarb — Nutrition Facts
| Rhubarb | per 100g |
|---|---|
| Calories | 21 kcal |
| Protein | 0.9 g |
| Fat | 0.2 g |
| Carbs | 4.54 g |
| Fiber | 1.8 g |
| Sugar | 1.1 g |
| Sodium | 4 mg |
| Potassium | 288 mg |
| Magnesium | 12 mg |
| Phosphorus | 14 mg |
| Vitamin C | 8 mg |
| Vitamin B6 | 0.024 mg |
| Folate | 7 mcg |
| Water | 93.6 g |
Source: USDA FoodData Central (FDC ID: 167758) · Data verified April 2026
Variations
Raw rhubarb
Raw rhubarb stalks are very tart and crunchy, with 21 kcal and 8mg vitamin C per 100g. Can be eaten as a snack dipped in a little sugar or salt. Maximum nutrient retention. The base data on this page is for raw rhubarb.
Stewed rhubarb (with sugar)
Stewed rhubarb with sugar has about 116 kcal per 100g (USDA data for frozen cooked with sugar). The calorie increase comes entirely from added sugar — about 29g sugar per 100g. For a lower-calorie option, use erythritol or stevia instead of sugar. The vitamin C drops from 8mg to about 3mg with cooking.
Frozen rhubarb
Frozen rhubarb without added sugar has virtually identical nutrition to raw — 21 kcal per 100g. Freezing is the best preservation method for rhubarb. Simply chop into 2-3cm pieces, spread on a tray to freeze individually, then bag. Keeps up to 12 months. No need to thaw before cooking.
Dietary Perspectives
For Weight Loss
Rhubarb is phenomenal for weight loss — only 21 calories per 100g, one of the lowest-calorie foods. A full cup diced (122g) has just 26 calories. The tart flavor naturally curbs sweet cravings. Cook with erythritol or stevia for a dessert with almost zero calories. The 86mg calcium supports metabolism.
For Athletic Performance
Rhubarb provides 288mg potassium per 100g — excellent for electrolyte balance. The 86mg calcium supports bone density and muscle contraction. Vitamin K (29.3µg) aids calcium metabolism. Low calorie content means it won't significantly impact energy intake. Best cooked into sauces or smoothies alongside higher-calorie protein sources.
For Keto
Rhubarb is one of the best plant foods for keto — only 2.7g net carbs per 100g (4.5g carbs minus 1.8g fiber). A generous 150g serving has just 4.1g net carbs. Its natural tartness makes it perfect for sugar-free desserts — cook with erythritol and cream for a keto-friendly crumble or fool. Much lower in carbs than most fruits.
Frequently Asked Questions
How many calories are in rhubarb?
100g of raw rhubarb has only 21 calories — one of the lowest-calorie foods that exist. One cup diced (122g) has just 26 calories. It is 93.6% water, making it extremely low in energy density.
Is rhubarb good for you?
Rhubarb is highly nutritious for its minimal calorie content. It provides 86mg calcium (7% DV), 29.3µg vitamin K (24% DV), 288mg potassium, and 8mg vitamin C per 100g. The high calcium content is notable — more than most vegetables. It also contains lutein and zeaxanthin for eye health.
Can you eat rhubarb on keto?
Rhubarb is excellent for keto — only 4.5g total carbs per 100g with 1.8g fiber, leaving 2.7g net carbs. One of the lowest-carb plant foods available. The challenge is that it needs sweetener due to extreme tartness — use erythritol or stevia.
Can you eat rhubarb raw?
Yes, rhubarb stalks can be eaten raw — they are very tart and crunchy. Some people dip raw stalks in sugar or salt. Raw rhubarb retains maximum vitamin C (8mg vs 3.3mg when cooked). Never eat rhubarb leaves — they contain high levels of oxalic acid and are toxic.
How does rhubarb compare to other low-calorie foods?
Rhubarb (21 kcal/100g) is lower in calories than celery (16 kcal), cucumber (15 kcal), and lettuce (15 kcal) on a per-serving basis because it is denser. It has far more calcium (86mg) and vitamin K (29µg) than most low-calorie vegetables.
How should you store rhubarb?
Fresh rhubarb keeps 1-2 weeks refrigerated in a plastic bag. For longer storage, chop and freeze — it keeps for up to a year frozen. Remove and discard all leaves before storing. Do not wash until ready to use.
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