Mayonnaise is one of the world's most popular condiments, but it brings almost no dietary fiber to your plate. The classic recipe — oil, egg yolk, vinegar, and seasonings — contains no plant cell walls, so a 100 g portion of standard mayo provides roughly 0 g of fiber. That fact is easy to overlook when you're tracking daily fiber, planning a low-carb or keto menu, or deciding whether your sandwich dressing helps your nutrition goals.
This calculator makes the picture clear. Choose a common mayo variety, or enter the values from your brand's nutrition label, then type in your portion to see the fiber per 100 g, the fiber in your actual serving, and its contribution to the Daily Value. It's a quick way to check whether a vegan, olive-oil, or high-fiber mayo is meaningfully different from the classic version — usually, it isn't.
How to Use This Calculator
Start by choosing the mayonnaise type that matches what's in your fridge. The preset options — regular, light, vegan, olive-oil blend, Kewpie-style, and homemade — all default to 0 g of fiber per 100 g, because that is what standard recipes deliver. If you are using a specialty product with fiber added (look for inulin, pea fiber, or citrus fiber in the ingredients), select Custom from nutrition label instead and enter the fiber grams and the serving size printed on the package. A typical label serving is 15 g — roughly one tablespoon.
Next, tell us how much mayo you actually used. You can type the portion in grams, tablespoons, or cups. If you prefer not to weigh anything, use the quick-fill buttons for 1 tbsp, 2 tbsp, ¼ cup, and the full 100 g baseline. Press Calculate fiber and you will get four numbers: fiber per 100 g, fiber in your portion, portion weight, and the percentage of the Daily Value that portion provides, based on the common 28 g fiber target.
Why Mayonnaise Is Essentially Fiber-Free
Dietary fiber comes from plant cell walls and related carbohydrates that the human gut cannot digest. Classic mayonnaise is an emulsion of oil, egg yolk, vinegar, salt, and sometimes lemon juice or mustard. None of those ingredients contains cell-wall material, so the fiber content rounds to 0 g per 100 g in nearly every commercial and homemade version. Reduced-fat mayos are no different: they generally replace oil with water and thickeners such as modified food starch or xanthan gum, which are not counted as fiber in standard nutrient databases.
The few exceptions are products that deliberately add functional fibers. Some vegan mayos use pea protein and inulin to improve texture, and a handful of high-fiber condiment brands add citrus pulp or oat fiber. That is exactly why the custom mode exists: it turns a small, rounded label number into a comparable per-100 g figure.
The math is a simple proportion: fiber per 100 g = (fiber per serving ÷ serving size in g) × 100. Portion fiber then follows from your chosen amount: portion fiber = (portion grams ÷ 100) × fiber per 100 g, and the Daily Value percent is (portion fiber ÷ 28) × 100.
Worked Examples
Example 1 — Standard store-bought mayo. You spread 21 g (about 1½ tbsp) on a sandwich. Regular mayo provides 0 g per 100 g, so your portion delivers 0 g of fiber. The 21 g portion counts toward your plate, but it contributes nothing to your fiber target.
Example 2 — Vegan mayo with added fiber. The label says 0.5 g fiber per 15 g serving. Fiber per 100 g = (0.5 ÷ 15) × 100 = 3.33 g. A 40 g portion (about 3 tbsp) contains (40 ÷ 100) × 3.33 = 1.33 g of fiber, which is 4.8% of a 28 g Daily Value. For context, that is still less than a slice of whole-wheat bread (about 2 g) and far less than a cup of raspberries (about 8 g).
Example 3 — Reading a rounded label. A light mayo label lists 0 g fiber with a 15 g serving. Because U.S. labeling rules allow fiber values below 0.5 g to be rounded down to zero, the true value could be anywhere from 0 to about 0.49 g per 15 g — which converts to up to about 3.3 g per 100 g. In practice, lab data from USDA FoodData Central shows light mayos near 0–0.3 g per 100 g.
Label Reading Tips
Serving size is the trap. A product that shows 0 g fiber per 15 g serving can contain up to about 0.3 g per 100 g before rounding rules force a nonzero listing. If you track fiber seriously, check the ingredient list first: with no plant-derived fiber source (inulin, chicory root, pea fiber, oat fiber, vegetable pulp), assume 0 g. If a fiber source is present, use the custom mode and prefer unrounded manufacturer data when you can find it.
Also remember that fiber is not the only reason to choose a mayo. Calorie density, fat type, and sodium matter too. Olive-oil mayos are still zero-fiber but swap some omega-6-heavy soybean oil for monounsaturated fat — a nutrition trade-off that has nothing to do with fiber. Official nutrient data for many generic entries is available at USDA FoodData Central.
Reference Data
| Mayo type | Typical fiber per 100 g |
|---|---|
| Regular mayonnaise (soybean/canola oil) | 0 g |
| Light / reduced-fat mayonnaise | 0 – 0.3 g |
| Vegan / plant-based mayonnaise | 0 – 2.5 g |
| Olive-oil blend mayonnaise | 0 g |
| Kewpie-style (Japanese) mayonnaise | 0 g |
| Homemade (egg yolk + oil + vinegar) | 0 g |
| High-fiber specialty mayonnaise | 1 – 5 g |
The table reflects rounded label values and typical food-database entries. Actual values depend on the brand's formula, so treat the numbers as a starting point rather than a guarantee.
Frequently Asked Questions
Can mayonnaise help me reach my daily fiber goal? No. Classic, light, olive-oil, and Kewpie-style mayos are effectively fiber-free. Only specialty products with added fiber sources move the needle — and even then, a typical sandwich portion delivers well under 1 g.
Should I count the fiber shown on a mayo label? Only if the number is nonzero. If it says 0 g, log zero; rounding means the truth is close to zero anyway. If it lists, say, 1 g per 15 g, convert to per-100 g before comparing brands.
Does homemade mayo have fiber? No. Egg yolk and oil are the base, and vinegar carries no fiber. If you blend in herbs, roasted garlic, or vegetable pulp, you add a small amount — usually under 1 g per 100 g.
Why does the calculator use 28 g as the Daily Value? That is the FDA's Daily Value for dietary fiber based on a 2,000-calorie diet, the target used on U.S. Nutrition Facts labels since the 2021 labeling update.