Melatonin Dosage Calculator
Select your reason for taking melatonin and the form of supplement you have on hand. The calculator returns the evidence-based dose range for that indication, your recommended starting dose, when to take it, how many units to buy for your therapy duration, and a plain-English explanation of how melatonin works. Results update instantly as you change any input.
What melatonin does and why dose matters
Melatonin is a hormone produced by the pineal gland in response to darkness. It does not sedate you directly; instead it signals to the brain that it is time to sleep, helping to shift and stabilise the body's internal clock (the circadian rhythm). Because it works as a signal rather than a sedative, the relationship between dose and effect is not linear. Taking 10 mg does not make you sleepier than 1 mg in a normal night-sleep context: once melatonin receptors are saturated (at around 0.3-1 mg), additional hormone has diminishing returns for sleep onset but increased risk of side effects such as next-day grogginess, headaches, and hormonal interference. Clinical research consistently finds that physiological doses of 0.3-0.5 mg are as effective as pharmacological doses of 3-10 mg for shifting the circadian clock, and often carry fewer adverse effects.
How to choose the right dose for your situation
The correct starting dose depends primarily on why you are taking melatonin, not on your body weight. Weight-based dosing is not standard practice for melatonin because it acts on receptors that saturate at very low concentrations. The indication matters most: general sleep-onset difficulty responds to 0.3-1 mg taken 30-60 minutes before bed, while jet-lag protocols call for 0.5-5 mg timed to the destination time zone. Shift workers with severely disrupted circadian rhythms may need 2-12 mg under medical guidance. Certain off-label uses such as endometriosis pain management use 10 mg, but these are specialist-supervised. Always begin at the lowest effective dose and increase only if you notice no effect after several consistent nights of use. Adults aged 65 and over should start at 0.3-0.5 mg: their melatonin clearance is slower, and lower doses are often equally effective.
Timing is as important as dose
Melatonin taken at the wrong time of day can shift your circadian rhythm in the wrong direction. For general sleep onset, 30-60 minutes before your desired bedtime is standard. For eastbound jet lag (crossing to a time zone where local time is later than home time), taking melatonin at 7 PM local time starting two days before departure and for four days after arrival helps advance the internal clock to align with the new time zone. Westbound travel (where local time is earlier) responds to melatonin taken at local bedtime for four days after arrival. Blue light exposure in the evening suppresses the body's own melatonin production, so reducing screen use in the hour before bed amplifies whatever dose you take. Melatonin is not a sleeping pill: it works best as part of good sleep hygiene rather than as a standalone fix.
Safety, side effects, and who should avoid melatonin
Melatonin is generally regarded as safe for short-term use in adults. Adverse effects are uncommon at doses below 5 mg but become more frequent above 10 mg and include next-morning drowsiness, headache, dizziness, nausea, and mood changes. There is no established lethal dose in humans, but doses above 30 mg are associated with substantial adverse effects. Melatonin interacts with anticoagulants (it can potentiate warfarin), anticonvulsants, immunosuppressants, and sedatives. People who are pregnant, breastfeeding, or trying to conceive should avoid melatonin supplements: melatonin has hormonal activity and there is insufficient safety data for these groups. People with diabetes, autoimmune conditions, or those taking blood-pressure medications should speak with their doctor first. Melatonin is not recommended for children unless prescribed by a paediatrician: the long-term effects on the developing hormonal system are not yet fully understood.
Melatonin dose ranges by indication
| Indication | Dose range (mg) | Timing | Max duration |
|---|---|---|---|
| Trouble falling asleep | 0.3-5 | 30-60 min before bed | 9 months |
| Shift work / disrupted cycle | 2-12 | 30-60 min before desired sleep | 4 weeks |
| Chronic insomnia | 2-3 | 30-60 min before bed | 29 weeks |
| Jet lag - eastbound | 0.5-5 | 7 PM local time (2 days pre-flight) | 6 days |
| Jet lag - westbound | 0.5-5 | Bedtime after arrival | 4 days |
| Blind individuals | 0.5-5 | 9-10 PM | Ongoing (medical supervision) |
| Beta-blocker insomnia | 2.5 | 30-60 min before bed | 4 weeks |
| Endometriosis | 10 | 30-60 min before bed | 8 weeks |
Evidence-based ranges compiled from published clinical trials and systematic reviews. Always start at the lowest effective dose.
Frequently asked questions
How much melatonin should I take to fall asleep?
For general difficulty falling asleep, 0.5-1 mg taken 30-60 minutes before your target bedtime is a well-supported starting point. Many people take far more than they need: commercial tablets are commonly sold in 5-10 mg doses, but research shows doses as low as 0.3 mg are effective for shifting the circadian signal. Start low and only increase if you see no improvement after a week of consistent use.
Does melatonin dosage depend on body weight?
No. Unlike many drugs, melatonin dosing is not adjusted by body weight in standard clinical guidelines. Melatonin works by binding to receptors that saturate at very low concentrations, so a heavier person does not need a proportionally larger dose. Indication (reason for use) and age are more relevant factors than weight.
Is it safe to take melatonin every night?
Short-term use (up to a few weeks) is considered safe for most healthy adults. Longer-term use for certain indications (such as chronic insomnia) has been studied for up to 29 weeks. However, nightly use for months or years is not well studied. Some researchers are cautious about long-term use suppressing the body's own melatonin production. For persistent insomnia it is better to identify and treat the underlying cause rather than relying on nightly supplementation indefinitely.
What is the best melatonin dose for jet lag?
For eastbound travel, 0.5-5 mg taken at 7 PM local destination time, starting two days before the flight and continuing four days after arrival, is supported by clinical trials. For westbound travel, 0.5-5 mg at local bedtime for four days after arrival is typical. Lower doses (0.5-1 mg) work for most people; higher doses (3-5 mg) may help with severe multi-time-zone crossings but increase the risk of grogginess. The direction of travel matters because eastbound shifts (advancing the clock) are harder for most people than westbound ones.
Can children take melatonin?
Melatonin is sometimes used for children with neurodevelopmental conditions such as autism spectrum disorder or ADHD when sleep difficulties significantly affect quality of life, but this should always be under the supervision of a paediatrician. The general guidance for children is to start at 0.5-1 mg taken 30-60 minutes before bedtime, but children's doses have not been established as rigorously as adult doses, and the long-term effects on hormonal development are not fully known. Good sleep hygiene should always be the first approach for children.
What happens if I take too much melatonin?
Doses above 10 mg commonly cause next-day grogginess, headache, dizziness, irritability, and nausea. Very high doses (above 30 mg) produce more pronounced effects. There is no established lethal dose in humans, but adverse effects scale with dose. If you accidentally take a very large amount and experience concerning symptoms, contact a poison control centre or medical professional. The key principle is that more is not better: the effective dose for most uses is 0.3-3 mg.
Should I take extended-release or fast-release melatonin?
Fast-release (immediate-release) melatonin is better for difficulty falling asleep because it produces a rapid peak that mimics the natural evening rise. Extended-release (prolonged-release) formulations may help if you have difficulty staying asleep or waking early, because they provide a more sustained level through the night. For jet lag and circadian shifting, immediate-release is generally preferred. Blood-pressure management (a less common use) is sometimes studied with prolonged-release forms.
Sources
- Arendt J, Skene DJ. Melatonin as a chronobiotic. Sleep Medicine Reviews. 2005;9(1):25-39. (Clinical review of melatonin dosing for circadian disorders)
- National Institutes of Health, Office of Dietary Supplements. Melatonin: Fact Sheet for Health Professionals. Updated 2023.
- Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews. 2002;(2):CD001520.