Omega-3 Dosing Calculator
Get a dose range for your goal, then predict where your Omega-3 Index lands after 13 weeks on a given dose and supplement form.
Each goal has a different evidence-backed dose range and EPA:DHA balance.
Salmon, sardines, mackerel, herring, trout. Used to estimate your baseline Omega-3 Index.
If you have a blood test result (%), enter it; it overrides the fish estimate.
Raises the baseline estimate by about 1 point. The dose you enter below is treated as replacing, not adding to, your current supplement.
Check the label or supplement facts panel; "fish oil concentrate" without a form claim is usually ethyl ester.
Sum of EPA + DHA per serving, not total fish oil. A "1,000 mg fish oil" softgel often has only ~300 mg EPA+DHA.
How this works
The Omega-3 Index (O3I) is EPA + DHA as a percentage of total fatty acids in red blood cell membranes. Values of 8-12% are associated with the lowest cardiovascular risk; the typical American sits at 4-5%. Because red cell membranes turn over slowly, the O3I reflects roughly the last 3-4 months of intake, much as HbA1c summarizes months of blood glucose.
The prediction curve implements the regression published by Walker and colleagues from 1,422 subjects across 14 randomized trials: change in O3I = 2.60 + 0.921 (if triglyceride form) − 0.842 × baseline + 0.050 × baseline² + 0.0027 × dose − 0.00000041 × dose², with dose in mg/d of EPA + DHA. The model explains 62% of the variance in response; dose alone carries about 80% of that explanatory power. The response it predicts is what trials observed at roughly 13 weeks, which is when most of the change has occurred. The quadratic dose term flattens and peaks near 3,300 mg/d, so this calculator caps the model there; higher intakes are extrapolation. The equation also shows why starting point matters: the higher your baseline, the smaller the gain from the same dose.
If you have not measured your O3I, the calculator estimates it from fish intake using survey data on about 3,500 people: adults eating no fish and taking no supplements average 4.1%, each step up in fish frequency adds roughly 0.5-0.65 points, and current supplement users run about 1 point higher.
Chemical form matters. In ethyl ester (EE) oils the fatty acids are bound to ethanol rather than a glycerol backbone; pancreatic lipase hydrolyzes the ethyl ester bond slowly, and absorption depends heavily on dietary fat in the same meal. Triglyceride and re-esterified triglyceride (rTG) oils absorb well regardless. In the Walker model, the TG form adds 0.921 O3I points over EE at the same dose (95% CI 0.63-1.15). If you use an EE product, take it with the fattiest meal of the day.
Goal-based dose ranges come from separate literatures: the 2019 AHA science advisory found 4 g/d of prescription omega-3 lowers triglycerides 20-30%; meta-analyses of depression trials find benefit specifically for EPA-predominant formulas (60%+ EPA) at 1-2 g EPA/d; pregnancy guidance targets at least 200 mg DHA/d.
References
Walker RE, et al. Predicting the effects of supplemental EPA and DHA on the omega-3 index. Am J Clin Nutr. 2019;110(4):1034-1040.
Skulas-Ray AC, et al. Omega-3 Fatty Acids for the Management of Hypertriglyceridemia: A Science Advisory From the American Heart Association. Circulation. 2019;140(12):e673-e691.
Kelaiditis CF, et al. Effects of long-chain omega-3 polyunsaturated fatty acids on reducing anxiety and/or depression in adults; a systematic review and meta-analysis of randomised controlled trials. Prostaglandins Leukot Essent Fatty Acids. 2023;192:102572.
Jackson KH, et al. Association of reported fish intake and supplementation status with the omega-3 index. Prostaglandins Leukot Essent Fatty Acids. 2019;142:4-10.