Omega-3 Units Explained: mg EPA, DHA, Total Omega-3, Grams of Fish and Conversions
What mg, g, "fish oil 1000 mg", EPA plus DHA and total omega-3 mean on a label, how to convert them with made-up examples, and which official figures use which unit.
Content last updated . This page has not been medically reviewed.
The terms
| Term on a label or in a study | What it means | Careful point |
|---|---|---|
| Fish oil (mg) | Weight of the oil | Not the omega-3 amount |
| EPA, DHA (mg) | Weight of each long-chain omega-3 fat | Add them to get "EPA plus DHA" |
| EPA plus DHA | The two marine omega-3 fats together | The figure most official bodies and trials use |
| Total omega-3 | Every omega-3 fat counted | Can include other omega-3s, so it may be larger than EPA plus DHA |
| ALA (g) | The plant omega-3 | A different fat, not interchangeable with EPA and DHA |
NCCIH, part of the US National Institutes of Health, describes fish oil supplements as containing EPA and DHA, and ALA as a different omega-3 found in plant oils such as flaxseed, soybean and canola. [1] How well the body turns ALA into EPA and DHA is covered on ALA, EPA and DHA: differences and the limits of conversion; we do not repeat it here.
Per serving, not per capsule
On a US Supplement Facts panel, the label must list the names and quantities of the dietary ingredients and the serving size. [2] One serving equals the maximum amount the label recommends per eating occasion. [2] So "per serving" can be two, three or more capsules. Rules in other countries differ and we did not review them here.Worked examples (hypothetical numbers, not real products)
| Made-up label | Serving | Fish oil | EPA | DHA | EPA plus DHA per serving | Per capsule |
|---|---|---|---|---|---|---|
| A | 2 softgels | 2,000 mg | 360 mg | 240 mg | 600 mg | 300 mg |
| B (concentrated) | 1 softgel | 1,000 mg | 500 mg | 250 mg | 750 mg | 750 mg |
| C | 3 softgels | 3,600 mg | 540 mg | 360 mg | 900 mg | 300 mg |
Steps: add the EPA and DHA lines for a serving, then divide by the number of capsules if you want to compare capsules. A and B could both say "1000 mg" on the front, yet one capsule holds 300 mg of EPA plus DHA and the other 750 mg. In example C the front might read "fish oil 1200 mg", but the EPA plus DHA is 900 mg per serving, not 3,600 mg. Liquids and gummies list a different serving unit (for example millilitres or pieces), so check the unit before comparing.
What real products list
One US analysis used the NIH Dietary Supplement Label Database and reviewed labels of 231 fish oil products. [3] Total EPA plus DHA per serving ranged from 60.2 mg to 2,684 mg, with an average of 697 mg. [3] The number of servings needed to reach 2,000 mg of EPA plus DHA, a target the authors chose for cholesterol lowering, ranged from 1 to 34. [3] That 2,000 mg figure is the study's benchmark, not advice. The spread shows why two bottles with similar front labels can differ a lot.Label versus laboratory
| Study | What it found | Note |
|---|---|---|
| 32 New Zealand products, 2015 | Only 3 of 32 contained EPA and DHA at or above the labelled amount [4] | Used gas chromatography |
| 47 New Zealand products, 2017 | 91% complied with EPA and DHA content claims [5] | Contradicts the 2015 result; the authors discuss possible reasons |
| 10 New Zealand products, 2020 | EPA and DHA in 90% were within 10% of the label [6] | Small sample |
Results differ by market, year and method, so none of these says how any one bottle behaves. Third-party testing programs are described on Quality testing and certifications.
Official figures and their units
| Group | Figure and unit | Body, year |
|---|---|---|
| Healthy adults and children, general heart health | 250 mg a day of EPA plus DHA described as an adequate intake | EFSA (EU), 2012 [7] |
| Adults, supplemental EPA plus DHA | Up to 5 g a day did not raise safety concerns | EFSA (EU), 2012 [7] |
| Adult men, 19 to over 70 years, ALA | 1.6 g a day adequate intake | Health Canada DRI table, page dated 2025 [8] |
| Adult women, 19 to over 70 years, ALA | 1.1 g a day adequate intake | Health Canada DRI table, page dated 2025 [8] |
Notice that the EPA plus DHA figures are in milligrams and the ALA figures in grams. Do not mix them. Full tables by age and life stage are on Omega-3 intake reference tables. We could not read the NIH Office of Dietary Supplements page (access blocked), so no ODS figure is given and we could not verify it.
Grams of fish to milligrams
Converting a portion of fish into milligrams of EPA plus DHA needs a food-composition table, and species, farming and cooking all change the answer. We did not use one on this page, so we give no conversion. NHS describes a portion of fish as around 140 g. [9] See fish and seafood omega-3 content tables for figures by species.Frequently asked questions
How many mg is 1 gram?
One gram is 1,000 mg. A label that lists 0.6 g of EPA plus DHA and one that lists 600 mg are the same amount.
Is "fish oil 1000 mg" the same as 1000 mg of EPA and DHA?
No. It is the weight of the oil. The EPA and DHA are listed separately and are only part of it, as the made-up examples above show. [2]
Is total omega-3 the same as EPA plus DHA?
Not necessarily. Total omega-3 counts every omega-3 fat on the label, so it can be higher than EPA plus DHA. Read the EPA and DHA lines.
Can I add ALA grams to EPA and DHA milligrams?
They are different fats and official figures use different units for them. EFSA and Health Canada give separate figures, so they should not be added together. [7] [8]
Is a higher number better?
Not as a rule. Trials of different amounts, products and groups gave different results, and some safety signals, such as atrial fibrillation, appeared more at higher amounts. [10] A clinician or pharmacist can say what suits a person.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.