How Much Fibre in Sweet Potato? Amounts by Size and Prep
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A medium sweet potato, roughly 130g cooked with the skin on, contains about 3.8 to 4g of fibre. If you are asking how much fibre in sweet potato you actually get, the short answer is around 3g per 100g, which works out to roughly 13% of the 30g daily fibre reference intake used in the UK from a single medium spud.
That number moves depending on size, whether the skin stays on, and how the sweet potato is cooked. Below is the breakdown, plus how sweet potato stacks up against other everyday fibre sources.
Fibre in sweet potato by size
Supermarket sweet potatoes vary wildly in size, which is why one label says 3g and another says 6g. Weight is the honest unit. Here is roughly what you get from baked sweet potato with the skin left on.
| Size | Approx. weight (cooked) | Fibre | % of 30g daily reference intake |
|---|---|---|---|
| Small | 60g | ~2g | ~7% |
| Medium | 130g | ~3.8g | ~13% |
| Large | 180g | ~5.3g | ~18% |
| Per 100g | 100g | ~3g | ~10% |
Figures are averages across common orange-fleshed varieties. Purple and Japanese types land in a similar range, with small differences by cultivar and growing conditions. Our complete sweet potato guide covers how varieties differ across nutrition, flavour, and texture.
Does the skin change the fibre count?
Yes, though less dramatically than people expect. Peeling a medium sweet potato removes roughly 0.5 to 1g of fibre, which is about 15 to 20% of the total. The skin is mostly insoluble fibre, while a good share of the soluble fibre sits in the flesh itself.
So peeling does not gut the fibre content, but leaving the skin on is free extra. If texture is the reason you peel, scrubbing well and roasting rather than boiling tends to make the skin far more pleasant to eat. There is more on this in our piece on whether you can eat sweet potato skin.
How cooking and prep change the fibre you get
Fibre is structural. It does not evaporate in the oven the way some vitamins degrade. What changes is the water content and therefore the weight you are measuring against.
Baking and roasting
Moisture cooks off, so the sweet potato gets lighter and the fibre concentrates slightly per 100g. A baked sweet potato reads a touch higher per gram than a raw one.
Boiling
The flesh absorbs water, so fibre per 100g looks lower. The total fibre in the whole potato has not really changed, it is just diluted across more weight.
Mashing and pureeing
Breaking down the cell walls does not destroy fibre, but it does change how quickly the food moves through you. Whole or chunky pieces generally feel more filling than a smooth mash.
Drying
Dehydrating removes water and leaves the fibre behind, so dried sweet potato is dense in fibre per gram. That is the principle behind a chewy dried sweet potato stick.
How sweet potato fibre compares with other everyday foods
Context helps. Sweet potato is a solid fibre contributor, though it is not a record breaker. Beans and lentils outrank it easily. What sweet potato does well is deliver fibre in a form people actually enjoy eating regularly.
| Food | Serving | Approx. fibre |
|---|---|---|
| Sweet potato, baked with skin | 130g | ~3.8g |
| White potato, baked with skin | 130g | ~2.8g |
| Cooked lentils | 100g | ~8g |
| Banana | 1 medium | ~3g |
| Wholemeal bread | 2 slices | ~4g |
| Yammy sweet potato sticks | 1 serving | 4g |
Most people in the UK eat closer to 18 to 20g of fibre a day against a 30g target, so a medium sweet potato closes a meaningful chunk of that gap. If you are adjusting fibre intake for a specific health or digestive reason, talk it through with your doctor or a registered dietitian first. For a deeper look at the numbers, see our breakdown of fibre in a sweet potato.
Frequently Asked Questions
Is sweet potato high in fibre?
It is a good source rather than a high-fibre food by strict labelling standards. A medium one with skin lands around 3.8g, which is respectable for a vegetable side but below pulses like lentils, beans, and chickpeas.
Do sweet potatoes have more fibre than white potatoes?
Slightly, yes. Gram for gram, sweet potato usually comes out about 1g ahead per medium serving with skins on. The bigger differences between the two sit in vitamin A content and sugar profile rather than fibre.
Does the colour of the sweet potato affect fibre?
Not much. Orange, white, and purple fleshed varieties all sit in a similar fibre range. Colour mostly signals different pigment compounds and a different flavour and texture, not a dramatically different fibre count.
Is dried sweet potato higher in fibre than fresh?
Per gram, yes, because the water has been removed and the fibre stays put. A small handful of dried sweet potato can match the fibre of a much larger fresh portion, which is what makes it a practical snack format.
How much fibre should I eat in a day?
UK guidance sets the reference intake at 30g a day for adults, with lower targets for children. Individual needs vary, so check with your doctor or a registered dietitian before making a large change to your intake.
A snack-sized way to hit your fibre target
Roasting a sweet potato is great at home and useless at 3pm on a train. That is the gap Yammy fills. Our chewy sweet potato sticks are made from real sweet potato and nothing complicated, with 4g of fibre and 3g of protein per serving.
They are naturally vegan and gluten-free, never deep-fried, and chewy in the way a good fruit leather is chewy. The Original, Salt & Pepper, and Sriracha flavours have no added sugar, so the sweetness is whatever the sweet potato brought with it. Keep a pack in your bag and the fibre maths gets a lot easier.