Walk down a supplement aisle and melatonin bottles typically top out at 5mg or 10mg per pill. Sleep research points somewhere very different: a meta-analysis of 17 studies (284 subjects) found the sleep-onset effect plateaus around 0.3mg, with higher doses adding side effects rather than benefit. Our free melatonin dosage calculator is built around that gap — here's the research behind it.
How much melatonin should I take, according to the actual research
Brzezinski et al. (2005), published in Sleep Medicine Reviews, remains one of the most-cited melatonin dose-response analyses. Its conclusion: the sleep-promoting effect plateaus at a low dose — around 0.3mg — and pushing the dose higher doesn't add more benefit, just more side-effect risk (like next-day grogginess). Harvard Health Publishing's more recent summary lines up with this: going above 2-3mg likely doesn't work any better than 1mg or less.
Melatonin dose too high: what's actually on store shelves
If the effective dose tops out around 1mg for most people, why are 5mg and 10mg pills the norm? Melatonin is regulated as a dietary supplement in the US, not a drug — so manufacturers aren't required to dose it at the research-backed minimum. Harvard Health also notes that the share of people taking more than 5mg per day has risen sharply in recent years, even though the evidence for extra benefit at that level is thin.
Melatonin 0.5mg vs 5mg vs 10mg: does more actually help you sleep better?
For typical sleep-onset or jet-lag use, no — the research doesn't support it. Our calculator shows the 0.3-1mg research-backed range next to common commercial doses (3mg, 5mg, 10mg) as a visual bar comparison, so the gap is obvious at a glance rather than buried in a paragraph.
Why this calculator isn't weight-based
Several melatonin calculators online use a weight-proportional formula — multiply your body weight in kilograms by some constant. We looked for a study supporting that approach and didn't find one. Melatonin is a signaling hormone whose receptors saturate at a low, roughly fixed dose, unlike a drug that's metabolized proportionally to body mass — so we didn't build a weight input into this calculator, and we explain why in the tool itself rather than just leaving it out silently.
Try the Melatonin Dosage Calculator → · Dosing another supplement too? See the Vitamin D Dosage Calculator.
Sources: Brzezinski A, Vangel MG, et al., "Effects of exogenous melatonin on sleep: a meta-analysis," Sleep Medicine Reviews (2005); Harvard Health Publishing, "Take melatonin supplements for sleep? Check your dosage"; Sleep Foundation, "Melatonin Dosage: How Much Melatonin Should I Take?" This is general health information, not medical advice — talk to your doctor about chronic insomnia or before starting any new supplement.
