7 August 2026

EPA and DHA: How to Read a Fish Oil Label

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Stand in front of two jars of fish oil and the first thing you see is a big number. 1000 mg. 1450 mg. It looks like the thing to compare, so most people compare it — and it’s the wrong number.

That figure is the weight of the whole capsule — the shell, the fish oil and everything else the formula adds — not the amount of omega-3 inside it. Only part of that weight is fish oil, and only part of the fish oil is the omega-3 you’re buying. The two jars can carry the same big number on the front and hold completely different amounts of what you came for.

The part that matters is two abbreviations, printed smaller, usually on the back.

EPA and DHA, and why only these two

Omega-3 is a family, not a single substance. Three members turn up in food and supplements:

• ALA — the plant one. Walnuts, flax, rapeseed, camelina.
• EPA — from marine sources.
• DHA — also marine.

They are not interchangeable. The body can convert a little ALA into EPA and DHA, but the conversion is inefficient, which is why plant sources and fish sources are talked about separately even though the family name is the same.

The approved health wordings in the EU are attached to EPA and DHA specifically — not to “omega-3” as a category. That’s the practical reason those two letters pairs are worth learning once:

EPA and DHA contribute to the normal function of the heart.

DHA contributes to the maintenance of normal brain function.

DHA contributes to the maintenance of normal vision.

They apply from a daily intake of 250 mg of EPA and DHA (for the brain and vision wordings, 250 mg of DHA). Those are the wordings a manufacturer is allowed to print. Anything more dramatic than that on a package is a claim nobody signed off on.

How to compare two jars in ten seconds

Find the percentages. A concentrated fish oil states them plainly — for example 38% EPA and 25% DHA, which is what’s on the jar I use.

Then check what they are percentages of. They are percentages of the fish oil, not of the whole capsule — the shell and the rest of the formula weigh something too. So the arithmetic the label is hoping you’ll skip is:

percentage × fish oil per capsule = milligrams per capsule

On my jar that’s 800 mg of fish oil in a 1450 mg capsule: 38% of it is about 300 mg of EPA, 25% is 200 mg of DHA. Multiply by the capsule size instead and you get 551 mg of EPA — almost double what’s really there.

Easier still: the nutrition table usually prints the milligrams of EPA and DHA per daily dose. If it’s there, compare that line and skip the arithmetic. Just note the dose it’s printed for. My jar says three softgels a day, swallowed whole with water after meals — which gives 900 mg of EPA and 600 mg of DHA. A jar dosed at one capsule a day and one dosed at three can’t be compared capsule for capsule.

A big capsule with low percentages can easily contain less EPA than a smaller capsule with high ones. Without this step, you’re comparing packaging.

If a label gives no percentages at all and only advertises the capsule size, that’s information in itself — the number they’re proud of is the one that costs them nothing.

What else is worth a look

The word “concentrated.” Plain fish oil sits at roughly a third omega-3 by weight. Anything substantially above that has been concentrated, and the percentages will say so.

Whether it declares fish. Fish oil is an allergen and has to be stated. On the jar I use it says so directly: contains fish.

How long a jar lasts. Divide the number of capsules by the daily dose, not by one. Ninety capsules at three a day is a month, not three months.

Gluten and lactose. Not relevant to most people, printed for those it is.

What no label can tell you

How much you personally need. That depends on how much oily fish you eat, and the answer for someone who has sardines twice a week is different from the answer for someone who never touches fish. A supplement is a supplement: it fills a gap in an otherwise varied diet, and it doesn’t replace one.

If you’re pregnant, breastfeeding, taking anticoagulants or under treatment for anything, this is a conversation for your doctor rather than for an article.

The short version

Ignore the number on the front. Turn the jar over and find the milligrams of EPA and DHA per daily dose — or multiply the percentages by the fish oil in a capsule, never by the capsule size. Compare that. It takes ten seconds and it’s the only comparison that means anything.