Serving guides
CBD dosage by weight: mg per kg, a starting range, and a two-week titration table
How studies dose CBD per kilogram, a conservative starting range by body weight, a two-week titration table, and mg-per-dropper math.
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Published CBD studies dose by body weight, in milligrams per kilogram. Consumer labels dose by dropper. This page connects the two so you can read a study, read a label, and pick a sensible starting point. The calculator on this page is a serving-size helper that does the arithmetic below; it is general information, not personalized guidance.
What does mg per kg mean in CBD studies?
It is the dose scaled to body weight. The prescription CBD product Epidiolex starts at 2.5 mg/kg twice daily (5 mg/kg/day) and tops out at 10 mg/kg twice daily (20 mg/kg/day) (FDA prescribing information). For a 70 kg adult that is 350 to 1,400 mg per day.
To convert, divide pounds by 2.2 to get kilograms, then multiply by the mg/kg figure. A 150 lb person weighs 68 kg; at 2.5 mg/kg that is 170 mg per dose. Those prescription numbers are useful as a ceiling, not a target: they were established with weekly dose increases, prescriber supervision and liver enzyme monitoring, and the label reports dose-related elevations of liver transaminases in 8% and 16% of patients at 10 and 20 mg/kg/day versus 3% on placebo (FDA prescribing information).
Consumer research sits two orders of magnitude lower and is not weight-scaled. The largest trial gave every participant the same 15 mg of CBD daily for 4 weeks, regardless of weight, in 1,793 adults; 12% reported a side effect and none were severe (Saleska et al., 2023). A 2017 safety review notes that chronic use up to 1500 mg per day has repeatedly been reported as well tolerated, with tiredness, diarrhea and appetite or weight changes the most common complaints (Iffland and Grotenhermen, 2017).
What is a sensible starting range by weight?
The calculator on this page uses 1 to 6 mg per 10 lb of body weight as a starting range, which is 0.22 to 1.3 mg/kg. That range is a site convention bracketed by the evidence, not a figure from a single study: its low end matches the 15 mg daily serving used in a 1,793-person trial for a 150 lb adult (Saleska et al., 2023), and its high end is still less than one-fourth of the prescription starting dose of 5 mg/kg/day (FDA prescribing information).
| Body weight | Low end (1 mg per 10 lb) | High end (6 mg per 10 lb) |
|---|---|---|
| 100 lb (45 kg) | 10 mg | 60 mg |
| 125 lb (57 kg) | 12.5 mg | 75 mg |
| 150 lb (68 kg) | 15 mg | 90 mg |
| 175 lb (79 kg) | 17.5 mg | 105 mg |
| 200 lb (91 kg) | 20 mg | 120 mg |
| 250 lb (113 kg) | 25 mg | 150 mg |
Start at the low end. Body weight matters less at these servings than people expect, because the whole range is far below the doses where the prescription trials saw weight-dependent effects. The high end is a ceiling for a two-week titration, not a goal. Published dosing guidance for cannabis preparations says to begin at modest levels and that titration "should be undertaken slowly over a period of as much as two weeks" (MacCallum and Russo, 2018).
How do you titrate over two weeks?
Hold each step for 3 to 4 days, change only the milligrams, and keep food timing constant. CBD's plasma half-life is 56 to 61 hours after a week of twice-daily dosing (FDA prescribing information), so each new serving takes days to reach a steady level.
Example for a 150 lb (68 kg) adult using a 50 mg/mL tincture:
| Days | mg per day | mg per 10 lb | Dropper (50 mg/mL) | Rule |
|---|---|---|---|---|
| 1 to 3 | 15 mg | 1 | 0.3 mL | Baseline serving; log sleepiness and digestion |
| 4 to 7 | 25 mg | 1.7 | 0.5 mL | Step up only if days 1 to 3 were uneventful |
| 8 to 10 | 37.5 mg | 2.5 | 0.75 mL | Same rule |
| 11 to 14 | 50 mg | 3.3 | 1.0 mL | Same rule; then hold or step back |
Stop stepping up when two consecutive steps look the same in your log; the lower one is your serving. Step back one row if you notice daytime sleepiness or loose stool, the two most frequently reported unwanted effects (Iffland and Grotenhermen, 2017). Nothing in this table reaches the 6 mg per 10 lb ceiling; most people never need to.
Take each serving the same way relative to meals. The prescription label reports that a high-fat, high-calorie meal increased peak concentration 5-fold and total exposure 4-fold compared with fasting, and the systematic review of 24 human studies found the same direction wherever food was tested (FDA prescribing information; Millar et al., 2018). Fed versus fasted is a bigger change than one dropper mark.
How do you convert a 1500 mg per 30 mL tincture to mg per dropper and per drop?
Divide total milligrams by milliliters: 1500 mg ÷ 30 mL = 50 mg per mL. A full 1 mL dropper is 50 mg, 0.5 mL is 25 mg, 0.25 mL is 12.5 mg. Only 25.00% of tinctures were accurately labeled in a JAMA analysis of 84 products (Bonn-Miller et al., 2017), so confirm the number on a batch certificate of analysis.
| Dropper mark | Volume | CBD at 50 mg/mL |
|---|---|---|
| Quarter | 0.25 mL | 12.5 mg |
| Half | 0.5 mL | 25 mg |
| Three-quarter | 0.75 mL | 37.5 mg |
| Full | 1.0 mL | 50 mg |
Per-drop figures depend on your dropper. Drop size changes with the tip, the carrier oil and the angle, so count once: squeeze out 1 mL by the mark, count the drops, and divide 50 mg by that count. If your dropper delivers 20 drops per mL, one drop is 2.5 mg; at 25 drops per mL, 2 mg. TODO: verify the drops-per-mL of the supplied dropper with a graduated syringe before publishing a per-drop figure.
Other bottle strengths follow the same arithmetic. 1000 mg in 30 mL is 33.3 mg/mL (a full dropper is 33 mg); 3000 mg in 30 mL is 100 mg/mL (a full dropper is 100 mg); 1500 mg in 15 mL is also 100 mg/mL. Compare bottles by mg per mL, never by the headline number. In the JAMA sample, 42.85% of products contained less CBD than labeled and 26.19% contained more, and THC was detected in 21.43% (Bonn-Miller et al., 2017); the certificate of analysis is the number that counts.
What does the calculator on this page do?
It multiplies your body weight in pounds by the 1 to 6 mg per 10 lb range above, then divides by your product's mg per mL to show a dropper mark. For a 150 lb adult that is 15 to 90 mg, or 0.3 to 1.8 mL of a 50 mg/mL tincture, with the two-week table starting at the low end (Saleska et al., 2023).
The calculator is a serving-size helper. It does not know your prescriptions, your liver history, or how you respond to CBD, and it does not replace the log. It produces general information, not personalized guidance. If you take prescription drugs, especially any with a grapefruit warning, review the serving with a pharmacist before starting, because the prescription label documents interactions through the CYP3A4 and CYP2C19 enzymes (FDA prescribing information).
This page is general information, not personalized guidance. FDA has not evaluated these statements.
General information, not personalized guidance.
Sources
- Epidiolex (cannabidiol) prescribing information, FDA SPL U.S. Food and Drug Administration (accessed 2026-10-13)
- A Systematic Review on the Pharmacokinetics of Cannabidiol in Humans (Millar et al., 2018) Frontiers in Pharmacology via PubMed Central (accessed 2026-10-13)
- An Update on Safety and Side Effects of Cannabidiol (Iffland and Grotenhermen, 2017) Cannabis and Cannabinoid Research via PubMed Central (accessed 2026-10-13)
- The Safety and Comparative Effectiveness of Non-Psychoactive Cannabinoid Formulations for the Improvement of Sleep (Saleska et al., 2023) Journal of the American Nutrition Association via PubMed (accessed 2026-10-13)
- Practical considerations in medical cannabis administration and dosing (MacCallum and Russo, 2018) European Journal of Internal Medicine via PubMed (accessed 2026-10-13)
- Labeling Accuracy of Cannabidiol Extracts Sold Online (Bonn-Miller et al., 2017) JAMA (accessed 2026-10-13)
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