The short answer (prices checked 6 November 2026)
- Lowest cost per day: the 365-tablet 14 mg ferrous fumarate pack at £4.99 works out at 1.4p a day, or 9.8p per 100 mg of iron.
- Highest cost per day on our shortlist: Solgar Gentle Iron 20 mg at £10.00 for 90 capsules, 11.1p a day. That is eight times the cheapest for 43 per cent more iron.
- The NHS says taking 17 mg a day or less of iron from supplements is unlikely to cause any harm. 8 of the 20 listings we read headline a dose above that figure.
- None of the 20 listings states any daily limit. One mentions the NHS, and gets the figure wrong.
Iron tablets are having their usual November. One listing, a 120-tablet pouch of iron with vitamin C, B12 and folic acid, sat at number 23 in Amazon UK's Health & Personal Care chart when we read it on 6 November 2026, and the top of that chart is thick with supplements people buy when the evenings get dark and they start feeling flat.
Iron is also the supplement where the labelling is hardest to read against the health advice. The number on the front of the pack, the number the law uses to work out what a label may claim, and the number the NHS talks about are three different numbers. Almost nobody selling iron explains which is which, so that is what this page does first.
One thing before the picks. Feeling tired is not a reason to start taking iron. Iron deficiency is diagnosed with a blood test, and the NHS route for persistent tiredness is a GP appointment rather than a supplement. Taking iron you do not need can cause real problems, and very high doses can be fatal for children. Keep the pack out of their reach.
Prices in this table come from Amazon and are refreshed at least once a day, with the date of the last update under the table. The cost-per-use and running-cost figures on this page use prices Look Into read on 6 November 2026, so they can differ from today's price.
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Prices and specs last checked by Look Into on 6 November 2026 · next check 1 January 2027 · how we picked
The three iron numbers, and why they disagree
14 mg is a labelling number. It is the Nutrient Reference Value for iron, set out in Annex XIII of Regulation (EU) No 1169/2011, which is the figure a label uses when it tells you a tablet gives "100% NRV". It is a labelling reference for the whole adult population. It is not a dose anyone has recommended to you.
8.7 mg and 14.8 mg are the intake numbers. The NHS puts the recommended daily amount of iron at 8.7 mg for men aged 19 and over, 14.8 mg for women aged 19 to 49, and 8.7 mg for women aged 50 and over. Those are totals from everything you eat, so most of it comes from food.
17 mg is the supplement number. The same NHS page says taking 17 mg or less a day of iron supplements is unlikely to cause any harm, and lists constipation, feeling sick, being sick and stomach pain among the side effects of doses over 20 mg. That 17 mg figure is the one worth holding in your head in the shopping aisle, and it is the one nothing on Amazon prints.
Why a 2.1 mg tablet can make the same promise as a 28 mg one
Nineteen of the twenty listings we read lean on tiredness or fatigue wording. That phrasing is not loose marketing. "Iron contributes to the reduction of tiredness and fatigue" is one of seven authorised iron health claims in the Annex to Regulation (EU) No 432/2012, alongside claims about cognitive function, energy-yielding metabolism, red blood cells and haemoglobin, oxygen transport, the immune system and cell division.
Here is the part the listings leave out. All seven claims carry one condition, and it is the same condition: the food has to be "at least a source of iron" as defined in the Annex to Regulation (EC) No 1924/2006. A "source of" a mineral means a significant amount, and Annex XIII of Regulation (EU) No 1169/2011 sets that at 15 per cent of the NRV. Fifteen per cent of 14 mg is 2.1 mg.
So the legal threshold for printing "helps reduce tiredness and fatigue" on an iron product is 2.1 mg a serving. The NHS comfort figure for supplements is 17 mg a day. Everything inside that eight-fold range carries exactly the same wording on the front of the box, and plenty of what is on sale sits above the top of it. The claim on the pack tells you nothing at all about the dose inside it.
How we picked these
We read the first 20 unsponsored results for "iron tablets" on amazon.co.uk on 6 November 2026 and recorded what each listing states about dose, iron compound and any daily limit. From that field we shortlisted six that cover distinct jobs, from the cheapest workable daily dose up to the high-strength end, and verified each one on its own product page for title, price and availability on the same day.
We then costed every pick two ways: pence per day at the dose the maker states, and pence per 100 mg of iron across the whole pack. The second figure is the one that survives a change of dose, and it is the one that moves most. Look Into has not handled these products: every figure comes from the maker, the listing or a named source, read on the date shown.
At a glance
| Product | Best for | Iron stated | Pack | Price 6 Nov 2026 | Cost per day | Per 100 mg iron |
|---|---|---|---|---|---|---|
| Iron Tablets High Strength 14 mg, 365 | Lowest cost per day | 14 mg ferrous fumarate | 365 tablets | £4.99 | 1.4p | 9.8p |
| Zipvit Iron Tablets 14 mg as Bisglycinate | Gentler form, same dose | 14 mg bisglycinate | 365 tablets | £9.99 | 2.7p | 19.6p |
| VitaBright Gentle Iron 28 mg | High strength | 28 mg bisglycinate | 180 tablets | £7.99 | 4.4p | 15.9p |
| Nutrition Geeks Iron Energy+ with vitamin C | Vitamin C in the same tablet | 14 mg | 120 tablets | £6.99 | 5.8p | 41.6p |
| Feroglobin Original Capsules | Best known UK name | Not stated on the listing | 30 capsules | £2.75 | 9.2p | Cannot be worked out |
| Solgar Gentle Iron 20 mg | Premium capsule | 20 mg bisglycinate | 90 capsules | £10.00 | 11.1p | 55.6p |
The six, in cost-per-day order
Iron Tablets High Strength 14 mg, 365 tablets
£4.99 on 6 November 2026 · 1.4p a day · 9.8p per 100 mg of iron
A year's tablets for the price of a sandwich. One tablet gives 14 mg of iron as ferrous fumarate, which is 100 per cent of the labelling NRV and sits under the NHS's 17 mg supplement figure. On cost per 100 mg of iron it beats the dearest pick here by a factor of nearly six, and nothing in the top 20 undercut it.
The catch: ferrous fumarate is the form people most often report constipation and stomach upset on, and if that happens the cheap pack stops being cheap. The listing's claim of "95% bioavailability relative to ferrous sulfate" is the seller's own figure with no study cited.
Zipvit Iron Tablets 14 mg as Bisglycinate, 365 tablets
£9.99 on 6 November 2026 · 2.7p a day · 19.6p per 100 mg of iron
The same 14 mg daily dose and the same year's supply, in iron bisglycinate, the chelated form usually reached for when ferrous salts upset the stomach. At 2.7p a day the premium over the cheapest pack is about £5 across a year, which is a sensible price for finding out whether the form is the thing that was bothering you.
The catch: this is the one listing in our 20 that cites the NHS, and it cites it wrongly. It calls 14 mg "the safe daily limit recommended by the NHS for both men and women". The NHS figure for supplements is 17 mg, and its recommended intakes are 8.7 mg for men and 14.8 mg for women aged 19 to 49. The 14 mg on the pack is the labelling NRV. The tablet is fine. The sentence is wrong.
VitaBright Gentle Iron 28 mg, 180 tablets
£7.99 on 6 November 2026 · 4.4p a day · 15.9p per 100 mg of iron
Double the labelling NRV in bisglycinate form, and the cheapest way on this list to buy a large amount of iron, at 15.9p per 100 mg. If a GP has told you to take more than the standard dose, this is the pack where the arithmetic works hardest.
The catch: 28 mg is well above the NHS's 17 mg supplement figure and above the 20 mg at which that page starts listing side effects, so this is a dose to take on advice rather than on a hunch. The listing's "patented Iron Bisglycinate Core Chelate" wording is the maker's own and gives no patent or certificate number to check.
Nutrition Geeks Iron Energy+ with vitamin C, B12 and folic acid, 120 tablets
£6.99 on 6 November 2026 · 5.8p a day · 41.6p per 100 mg of iron
This is the listing that put iron on the chart: number 23 in Amazon UK's Health & Personal Care best sellers on 6 November 2026. Each tablet carries 14 mg of iron plus vitamin C, B12 and folic acid, so the vitamin C that helps non-haem iron absorb is already in the dose rather than in a glass of orange juice you have to remember.
The catch: 120 tablets at £6.99 is four times the daily cost of the identical 14 mg dose in a 365-tablet pack, and a glass of orange juice is cheaper than the difference. You are paying for the convenience of one tablet, not for more iron.
Feroglobin Original Capsules, 30 capsules
£2.75 on 6 November 2026 · 9.2p a day · cost per 100 mg cannot be worked out
Vitabiotics is a British company and Feroglobin has been on UK pharmacy shelves for decades, which is worth something if you would rather buy a name your pharmacist recognises than a pouch from a marketplace seller. The capsules pair iron with folic acid and B12 and are formulated to be gentle on the stomach.
The catch: the Amazon listing states no iron figure anywhere. Not in the title, not in the bullets, not in the specification table. That makes it the only pick here you cannot put on a cost-per-milligram footing, and at £2.75 for 30 capsules it is the most expensive of the cheap options per day. Check the pack or Vitabiotics' own page before you compare it with anything else.
Solgar Gentle Iron 20 mg, 90 vegetable capsules
£10.00 on 6 November 2026 · 11.1p a day · 55.6p per 100 mg of iron
Solgar is the brand most often handed over the counter in a health food shop, and this is the one listing of the six whose bullets quote the authorised claim wording properly and give the NRV percentage, 143 per cent, rather than leaving you to work it out. Bisglycinate again, in a vegetable capsule.
The catch: it is the dearest pick here by a distance, 11.1p a day against 1.4p for the cheapest, and the 20 mg dose is above the NHS's 17 mg supplement figure and at the level where that page begins listing side effects. You are paying roughly eight times the cheapest daily cost for 43 per cent more iron.
What the first 20 listings actually say
We read the first 20 unsponsored results for "iron tablets" on amazon.co.uk on 6 November 2026 and counted what each one states, looking only at the product title, the About this item bullets, the technical specification tables and the product description. Here is the count.
| What we looked for | Out of 20 |
|---|---|
| Use tiredness or fatigue wording | 19 |
| State a dose above the NHS's 17 mg supplement figure | 8 |
| Name which iron compound is used | 12 |
| Give no iron figure at all | 3 |
| State any daily limit, upper level or do-not-exceed figure | 0 |
| Mention the NHS | 1, and it states the figure wrongly |
The eight above 17 mg headline 18, 20, 20, 25, 27, 28, 28 and 28 mg. None of them says anything about an upper figure, which is legal, because no law requires it. The three that give no number at all include two premium brands, so this is not only a cheap-seller problem.
Our reading of all that: the dose on an iron pack is a marketing decision inside a range where the label wording never changes. If you are buying iron without a blood test behind you, the 14 mg packs are the ones that keep you below the figure the NHS is comfortable with, and they happen to be the cheapest per day as well.
Frequently asked questions
How much iron should I take a day?
The NHS puts the recommended daily amount at 8.7 mg for men aged 19 and over, 14.8 mg for women aged 19 to 49 and 8.7 mg for women aged 50 and over, and says most people should be able to get all the iron they need from their diet. For supplements specifically it says 17 mg a day or less is unlikely to cause any harm. If you think you are deficient, ask a GP for a blood test rather than guessing a dose.
Is a 28 mg iron tablet too much?
It is above the figure the NHS describes as unlikely to cause harm, which is 17 mg a day from supplements, and above the 20 mg at which that page lists constipation, feeling sick, being sick and stomach pain as side effects. That does not make a 28 mg tablet unsafe for everyone, and doses in that range are routinely prescribed for diagnosed deficiency. It does mean a 28 mg pack is a decision to take with a clinician rather than off a chart position.
Which form of iron is gentlest on the stomach?
Iron bisglycinate is the form marketed as gentle, and it is what the products labelled "gentle iron" on this page use. Ferrous fumarate and ferrous sulphate are the cheaper salts and are the ones people most often report constipation on. Individual tolerance varies enough that the honest advice is to start with the cheap pack and switch form if it disagrees with you, rather than paying the bisglycinate premium up front.
Why does every iron supplement say it reduces tiredness and fatigue?
Because it is an authorised health claim. "Iron contributes to the reduction of tiredness and fatigue" appears in the Annex to Regulation (EU) No 432/2012, and the only condition attached is that the product is at least a source of iron. A source of iron means 15 per cent of the 14 mg Nutrient Reference Value, so 2.1 mg a serving is enough to earn the sentence. The wording is a legal entitlement rather than a comment on the dose.
Does vitamin C help iron absorb?
Vitamin C is widely used alongside non-haem iron for that reason, which is why several of the bestselling packs bundle it in. Whether you need to pay for it in the same tablet is a different question. On our numbers the combined tablet costs 5.8p a day against 1.4p for the same 14 mg of iron on its own, so the convenience costs about £16 a year.
Sources
- NHS, Vitamins and minerals: Iron, read 6 November 2026, for the 8.7 mg and 14.8 mg recommended amounts, the 17 mg supplement figure and the side effects listed above 20 mg.
- Regulation (EU) No 432/2012, Annex: list of permitted health claims, read 6 November 2026, for the seven authorised iron claims and their shared condition of use.
- Regulation (EU) No 1169/2011, Annex XIII, read 6 November 2026, for the 14 mg Nutrient Reference Value for iron and the 15 per cent significant-amount threshold.
- Regulation (EC) No 1924/2006, Annex: nutrition claims, read 6 November 2026, for the conditions attached to "source of" and "high in" a mineral.
- Amazon.co.uk Best Sellers, Health & Personal Care, read 6 November 2026, for the chart position cited.
Look Into is a Whito Ltd publication. We earn a commission if you buy through the Amazon links on this page, at no extra cost to you. Prices in the text and cards are the buy-box price read on 6 November 2026 and change often; the comparison table above the article is a live feed. Nothing here is medical advice. Speak to a GP or pharmacist before starting an iron supplement, and keep iron out of the reach of children.