Comparison
Omega-3 vs Fish Oil: What's the Difference?
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Shops use “omega-3” and “fish oil” almost as if they mean the same thing. They don’t quite, and the difference helps you read a label. For the evidence, see our omega-3 guide, and for products see best omega-3 supplements.
Side by side
| Omega-3 A family of fats; EPA and DHA are the two main long-chain types | Fish oil A supplement made from fish; one source of EPA and DHA | |
|---|---|---|
| What it is | Fats your body can't make well itself. The two main long-chain types, EPA and DHA, come mostly from oily fish and from fish oil and algae oil supplements. | A supplement oil made from fish, so it is a source of omega-3, not an alternative to it. Algae oil is another source. |
| What to check on the label | EPA and DHA per serving. | The EPA and DHA amounts per serving, not just the "fish oil" total, because they are smaller. The NIH says a typical 1,000 mg fish oil capsule contains about 180 mg EPA and 120 mg DHA, though this varies widely. |
| Evidence strength | We rate it C: mixed, with benefits limited to particular outcomes. | The same evidence applies to EPA and DHA from any source. See our omega-3 guide. |
| What research shows | A major review found omega-3 supplements make little or no difference to deaths or heart events in most people. The clearest effect is on triglycerides (about 15% lower on average). | Same. Higher doses have been linked to a higher chance of an irregular heartbeat (atrial fibrillation). |
| Typical cost (per 1 g EPA plus DHA) | Algae oil, a fish-free source: £0.740 (WeightWorld) and £1.01 (Healthspan) in the UK, or $1.76 (Nordic Naturals) in the US. Fish oil is in the next column. | Fish oil: from £0.296 (UK, sale price) or $0.719 to $0.883 (US) in our product data, checked Nov 1 to 3, 2026. Algae oil costs more per gram in our data. |
| Who might prefer it | People who get omega-3 from oily fish: the NHS advises at least 2 portions of fish a week, including 1 of oily fish. | People who want a supplement. Algae oil is an option if you avoid fish. |
Our verdict
Omega-3 and fish oil aren't competing choices. Omega-3 is the type of fat, and fish oil is one supplement that supplies it. What matters on a label is the amount of EPA plus DHA per serving. Oily fish is a simpler place to start.
Where to buy
The short version
Omega-3s are fats your body can’t make well itself. The two main long-chain types are EPA and DHA. They come mostly from oily fish such as salmon, mackerel and sardines, and from fish oil and algae oil supplements. So “fish oil” is one way to get omega-3, and algae oil is another.
What to look for on the label
Look for the EPA and DHA amounts per serving, not just the “fish oil” total. The NIH says a typical 1,000 mg fish oil capsule contains about 180 mg EPA and 120 mg DHA, though this varies widely. Our product data shows the range: one product gives 695 mg EPA plus DHA per gelcap, another 1.6 g per two capsules. We have not reviewed krill oil or cod liver oil, so we make no claim about them.
Algae oil products in our data give 510 mg (one Healthspan capsule) to 900 mg (three WeightWorld softgels) of EPA plus DHA per serving, so you may need two or three capsules to reach 1 g. WeightWorld’s serving is inferred from its pack size and the Nordic Naturals amounts come from a search result, so check both labels.
What the evidence says
A major review found that omega-3 supplements make little or no difference to deaths or heart events in most people. The clearest effect is on triglycerides, a type of blood fat. Higher doses have also been linked to a higher chance of an irregular heartbeat called atrial fibrillation. We rate the evidence C. See the omega-3 guide for the details and citations.
Talk to your doctor or pharmacist
Talk to your doctor or pharmacist before you start any supplement, especially if you are pregnant or breastfeeding, take prescription medicine, or have a health condition. Ask first if you take blood thinners such as warfarin, have a bleeding disorder, an irregular heartbeat, or a fish or shellfish allergy.
FAQ
Is omega-3 the same as fish oil?
Not exactly. Omega-3 is a type of fat, and fish oil is a supplement that supplies it. Algae oil is another source.
How much EPA and DHA is in a fish oil capsule?
It varies a lot. The NIH says a typical 1,000 mg fish oil capsule has about 180 mg EPA and 120 mg DHA, so check the label for EPA and DHA per serving.
Are krill oil or cod liver oil different?
We haven’t reviewed them, so we make no claim.
Is there an option if I avoid fish?
Yes. Algae oil supplies EPA and DHA without fish. In our product data it costs more per gram than fish oil: £0.740 to £1.01 in the UK and $1.76 in the US, against £0.296 and $0.719 to $0.883 for fish oil.