Free tool
Fibre calculator
Add up the fibre in a normal day of everyday UK foods and see how close you come to the 30 g a day the UK recommends for adults. Figures come from the UK's official food composition data, per typical portion.
Figures checked See sources
- Your age
- What you eat in a day
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How much fibre do you need a day?
The UK recommends 30 g of fibre a day for adults, set by the Scientific Advisory Committee on Nutrition (SACN) in 2015. Children need less:
| Age | Fibre a day |
|---|---|
| 2 to 5 | about 15 g |
| 5 to 11 | about 20 g |
| 11 to 16 | about 25 g |
| 16 and over | about 30 g |
Most people fall well short. In the latest National Diet and Nutrition Survey (2019 to 2023), adults aged 19 to 64 averaged 16.4 g a day, and only 4% of adults reached 30 g.
What 30 g looks like
Here is one day from the figures in the calculator: porridge (3.5 g), two slices of wholemeal bread (5.6 g), half a can of baked beans (9.8 g), a baked potato with its skin (5.7 g), a pear (2.2 g) and a portion of raspberries (3.0 g). That comes to about 30 g.
The same day with white bread, peeled potatoes and no beans lands nearer 15 g, which is roughly where the average adult sits.
Easy ways to add fibre
- Swap white bread, rice and pasta for wholemeal or wholewheat. Two slices of wholemeal bread have 5.6 g of fibre against 2.3 g for white, and a portion of wholewheat spaghetti 7.6 g against 3.1 g.
- Add a portion of beans, lentils or chickpeas to stews, curries, soups and salads. Half a can of baked beans has 9.8 g.
- Keep the skins on potatoes.
- Have fruit or a small handful of nuts or seeds as a snack.
Go up gradually. The British Dietetic Association says to increase fibre slowly so your gut can adjust, and to drink plenty of fluid, because fibre draws water into the bowel.
How the calculator works
Pick the age, then tap + for each portion you eat in a normal day. It adds up the fibre and compares the total with the UK recommendation for that age. On a larger screen it also suggests the highest-fibre portions you haven't picked yet.
The figures are AOAC fibre, the measure the 30 g target is based on, taken from McCance and Widdowson's Composition of Foods Integrated Dataset (CoFID), the UK's official food tables. A few foods with no AOAC value in CoFID (chia seeds, linseed and dark chocolate) use US Department of Agriculture data measured the same way; their rows say so. Portion sizes come from the British Nutrition Foundation's portion guide and NHS 5 A Day portions. Brands and recipes vary, so treat the total as an estimate. Packaged foods list their own fibre on the label, per 100 g.
If you are thinking about a fibre supplement, our guide to psyllium husk explains how it works and how to take it safely.
Common questions
How much fibre should I eat a day?
Adults in the UK are advised to eat 30 g of fibre a day. Children need about 15 g at 2 to 5 years, 20 g at 5 to 11 and 25 g at 11 to 16.
How much fibre is in porridge?
A 45 g portion of dry porridge oats has about 3.5 g of fibre, using the UK's CoFID food data. Topping it with raspberries (3.0 g per 80 g) or a spoonful of seeds adds more.
Which foods are highest in fibre?
Per typical portion in the calculator, half a can of baked beans (9.8 g), wholewheat spaghetti (7.6 g), chia seeds (6.9 g per 20 g), chickpeas (5.7 g), a baked potato with its skin (5.7 g) and two slices of wholemeal bread (5.6 g) are near the top.
Is it bad to eat too much fibre?
There is no UK upper limit, but raising fibre quickly can cause wind and bloating. The British Dietetic Association advises increasing it gradually and drinking plenty of fluid. If you have a bowel condition, follow the advice of your GP or dietitian.
Sources
These tools give general information, not medical advice. If you have a medical condition, take prescription medicines, or are pregnant or breastfeeding, speak to your GP, pharmacist or a dietitian.
Further reading
Gut and fibre
Psyllium husk: what it is and how to take it
Psyllium husk is the seed coat of the Plantago ovata plant, a soluble fibre that soaks up water and turns to gel, sold in the UK both as a licensed laxative called ispaghula husk (Fybogel is one widely sold brand) and as a food supplement powder. Take it stirred into plenty of water, away from medicines and bedtime, and build up slowly.
11 min read
Vitamins and minerals
Foods high in magnesium: a UK list
Seeds, nuts, wholegrains, beans and some leafy greens are the richest everyday sources: a 30 g handful of Brazil nuts or sunflower seeds gives more than 100 mg, over a third of what an adult needs in a day. Most people can get enough from a varied diet, and low magnesium is something a GP diagnoses with a blood test, not something to guess from symptoms.
8 min read
Vitamins and minerals
Signs of low iron: symptoms and tests
The commonest signs of low iron are tiredness, shortness of breath, palpitations, paler skin and headaches. Less common ones include tinnitus, craving ice, hair loss, restless legs and spoon-shaped nails. None of them is specific to iron, so the way to find out is a blood test from your GP.
12 min read
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