Wondering how many calories are in your serving of choy? This calculator estimates calories and macros for bok choy, choy sum, and napa cabbage. Enter an amount in grams, ounces, or cups, choose your variety, and multiply by servings for a full meal or recipe.
Choy is a nutrient-dense, low-calorie leafy green popular in Asian cooking and everyday meal prep. A full cup of raw bok choy contains fewer than 10 calories, so it adds volume and nutrients without breaking your calorie budget. This tool helps with portion tracking, low-calorie side dishes, and consistent logging.
Use the quick-fill buttons for common serving sizes, or enter a custom amount to match your plate. The results panel breaks down calories per serving and total calories, plus protein, carbs, and fat, making it useful for macro trackers and balanced meal planning.
How to Use This Tool
Start by selecting your choy variety from the dropdown — the calculator supports bok choy (pak choi), choy sum, and napa cabbage, each with its own calorie and macro values per 100 grams. Next, enter the amount you plan to eat and choose the matching unit: grams, ounces, raw shredded cups, or cooked cups. If you're logging a recipe or a full meal, enter how many servings of that amount you're having. Press Calculate to see the calories per serving, the total calories across all servings, and a breakdown of protein, carbohydrates, and fat.
The quick-fill buttons below the inputs let you jump straight to common serving sizes such as 1 cup raw, 1 cup cooked, or 100 g. After a calculation, you can adjust any value and recalculate instantly. Use the Reset button to return to the default 100 g bok choy example.
Calorie Reference Table
The table below shows the nutrition values used by the calculator, expressed per 100 grams of raw vegetable. These figures are adapted from USDA FoodData Central and represent averages across common retail varieties.
| Choy variety | kcal / 100 g | Protein | Carbs | Fat |
|---|---|---|---|---|
| Bok choy (pak choi) | 13 | 1.5 g | 2.18 g | 0.2 g |
| Choy sum | 15 | 1.5 g | 2.7 g | 0.3 g |
| Napa cabbage | 12 | 1.2 g | 2.5 g | 0.2 g |
Values rounded to one decimal place. Cooked choy can contain slightly different calories per gram because water is absorbed during boiling or steaming, but the total calories in the vegetable itself remain nearly unchanged.
Worked Examples
Let's walk through a few typical scenarios so you can see how the math works.
Example 1 — Raw bok choy. You're making a salad and use 150 g of raw bok choy leaves. Divide 150 by 100 to get a factor of 1.5. Multiply by 13 kcal per 100 g: 1.5 × 13 = 19.5 kcal for the whole serving. Protein is 1.5 × 1.5 = 2.3 g, carbs are 1.5 × 2.18 = 3.3 g, and fat is 1.5 × 0.2 = 0.3 g.
Example 2 — Cooked choy sum. One cup of cooked choy sum weighs about 170 g. That gives a factor of 1.7. The calculator multiplies 1.7 by 15 kcal per 100 g: 1.7 × 15 = 25.5 kcal per cup. If you eat two cups as a side dish, the total becomes 51 kcal — still a very light addition to your plate.
Example 3 — Napa cabbage in a stir-fry. You add 200 g of shredded raw napa cabbage to a large stir-fry and then divide the finished dish into four equal servings. Since 200 g ÷ 4 = 50 g per serving, each portion contains 0.5 × 12 = 6 kcal from the napa cabbage. Remember to budget for oil and sauce separately.
Why Estimates Can Vary
Leafy green vegetables naturally contain a lot of water — often 90% or more — so their calorie density is low. However, the exact water content depends on the growing conditions, the season, and how the vegetable is stored. The values in this calculator are based on raw, ready-to-eat vegetable data commonly used in nutrition databases. If you weigh a portion after boiling or steaming, the scale will show a higher number because absorbed water adds weight while contributing no calories, which makes the per-gram calorie figure appear lower. The total calories in the vegetable remain essentially the same.
For the best results, record the weight of raw choy before cooking whenever you're logging a meal. If you only have a cooked weight, don't panic — you can still estimate using the cooked-cup conversion, but treat the result as a rough approximation rather than an exact number.
Tips for Accurate Portion Tracking
When you prep a large batch once and eat it across several days, weigh the raw vegetable before cooking, then divide the finished dish into equal containers. For example, if 300 g of raw bok choy ends up as two dinner portions, each portion contains 150 g of the vegetable, or about 19.5 kcal.
When building a recipe, add each ingredient separately rather than estimating the whole dish by eye. Choy is so low in calories that the biggest errors usually come not from the vegetable itself, but from the cooking oil, soy sauce, sesame oil, or oyster sauce used in the pan — those add 40 to 120 kcal per tablespoon. Use the tips above and keep your choy portion consistent to make your tracking far more reliable.
Frequently Asked Questions
Is choy a low-calorie vegetable? Yes. Bok choy, choy sum, and napa cabbage all come in below 20 kcal per 100 g, which makes them excellent for adding volume, fiber, and micronutrients to meals without a meaningful calorie load.
Should I measure raw or cooked? For meal planning and recipe logging, measure raw. Nutrition databases are usually built around raw weights. If you must use a cooked measurement, choose the cooked-cup option in the calculator and understand that the result is a rough estimate because water absorption varies.
Can I use the same values for frozen choy? Frozen vegetables are usually blanched before freezing, so their calorie content per 100 g is very close to raw. Weigh the frozen portion after thawing and draining excess water for a reasonable estimate, or use the raw option with a little forgiveness.
Additional Resources
The nutrition values in this calculator are adapted from USDA FoodData Central, which provides standardized nutrient data used by dietitians and researchers: fdc.nal.usda.gov. For more about the plants themselves, see the Wikipedia entries for bok choy, choy sum, and napa cabbage.