What this calculator does, and what it deliberately does not do
This is a unit conversion tool. A licensed tincture is sold with a laboratory measured total printed on its label, and that total, spread across the volume of the bottle, gives a concentration. Once the concentration is known, every other quantity is simple division or multiplication: milligrams per millilitre, milligrams per drop, and the volume that contains any chosen number of milligrams. The calculator performs exactly those steps and stops there. It does not suggest a starting amount, it does not adjust for the person using it, and it does not predict how any amount will feel. Those are not arithmetic questions. The strength of a product, a person's tolerance, what else they have eaten or drunk, and the law where they live all sit outside anything a calculator can know. Treating a converted number as a recommendation would be a misuse of the tool, and the page is written throughout on the basis that amounts and advice are different things.
Reading the label before doing any arithmetic
The calculation is only as good as the two numbers fed into it, and both come from the label, so the label deserves a careful read. Licensed products state the total THC content of the whole container in milligrams, and the container volume in millilitres. Some labels also state a per serving figure, and confusing the serving figure with the bottle total is the most common way this arithmetic goes wrong: a bottle described as holding thirty servings of 10 mg contains 300 mg in total, and using 10 mg as the bottle total would understate the concentration thirty fold. Labels may also list THCA alongside THC. THCA is the compound as it occurs in the raw plant; it is converted to THC by heat, in a step called decarboxylation, and tinctures are generally made from material that has already been through it, which is why the labelled THC figure is the one to use for a finished tincture. If a label gives both, a combined potential figure is sometimes printed as total THC, calculated by the producer. Use the figure the label presents as the total for the bottle as sold, and if the label is unclear, the honest position is that the concentration is not known precisely, and no calculator can repair that.
The arithmetic, step by step
Everything follows from one division. Take a bottle labelled 1000 mg of THC in 30 mL. The concentration is 1000 divided by 30, which is 33.3 mg per mL, rounded. A drop is smaller than a millilitre: the conventional standard dropper delivers 20 drops of a water like liquid per millilitre, so one drop of this tincture holds 33.3 divided by 20, about 1.7 mg. Working in the other direction, an amount of 5 mg occupies 5 divided by 33.3, which is 0.15 mL, and 0.15 mL at 20 drops per mL is about 3 drops. The table below shows the same working for a range of bottle totals in a 30 mL bottle, and it is all the chart at the top of this page displays: stronger bottles put more milligrams into every drop, in exact proportion.
| Total THC in a 30 mL bottle | mg per mL | mg per drop (at 20 drops per mL) | Volume holding 5 mg |
|---|---|---|---|
| 100 mg | 3.3 mg | about 0.17 mg | 1.5 mL |
| 250 mg | 8.3 mg | about 0.42 mg | 0.6 mL |
| 500 mg | 16.7 mg | about 0.83 mg | 0.3 mL |
| 750 mg | 25 mg | about 1.25 mg | 0.2 mL |
| 1000 mg | 33.3 mg | about 1.67 mg | 0.15 mL |
These figures are illustrations of the arithmetic worked from round label numbers, not descriptions of particular products and not suggested amounts. The 5 mg column exists because 5 mg is a convenient amount for showing the method; the same division works for any amount a person types in.
Why the drop figure is an approximation, and always will be
The 20 drops per millilitre figure is a convention, not a property of any particular dropper. It comes from the standard medicine dropper, defined so that it delivers 20 drops of water to the millilitre. Real tincture droppers differ from that standard in several ways at once. The size of the opening in the pipette varies between manufacturers. The liquid itself matters: an oil based tincture and an alcohol based tincture form drops of different sizes, and the same liquid forms different drops when cold and viscous than when warm. The angle of the dropper and the speed at which drops are squeezed out matter too. The result is that a counted number of drops can easily deliver a volume noticeably different from the nominal one, in either direction. For that reason many product droppers are printed with millilitre graduations, commonly at 0.25, 0.5, 0.75, and 1.0 mL, and measuring to a printed line is a materially more reliable method than counting drops. This calculator reports the drop figure because people ask for it and because it gives a reasonable sense of scale, and it labels that figure as approximate every time it appears. Where precision matters, the millilitre figure and a graduated dropper are the better tools.
Timing: why swallowed tincture is not comparable to smoking
A tincture can be used in two ways, and they behave differently. Held under the tongue, some of the THC is absorbed through the lining of the mouth directly into the bloodstream. Swallowed, whether immediately or after being held briefly, the rest travels to the stomach and then to the liver, where a portion of it is converted into a related active compound, 11-hydroxy-THC, before it circulates. The practical consequences are about timing, and public health authorities describe them consistently. Health Canada advises that effects from eating or drinking cannabis can take from 30 minutes to 2 hours to begin, and can last up to 12 hours. The United States Centers for Disease Control and Prevention makes the same point about edible products: the effects are delayed compared with smoking, and they last longer, because the product has to be digested and processed first. Inhaled cannabis, by contrast, is absorbed through the lungs within minutes. The slow onset of a swallowed dose is the feature most often misunderstood, because an hour can pass with little felt effect while absorption is still under way, and the full effect arrives later and persists for hours. Anyone comparing amounts across routes should understand that the milligram figure is only one part of the picture, and that onset and duration differ so much between routes that the experiences are not interchangeable.
Safety points that have nothing to do with arithmetic
Some cautions apply to these products whatever the numbers say. Cannabis impairs driving and the operation of machinery, and the impairment lasts well beyond the point where a person may feel it has worn off; Health Canada advises against driving after use. Combining cannabis with alcohol increases impairment, and the same caution applies alongside sedating medicines. The United States Centers for Disease Control and Prevention advises against cannabis use during pregnancy and while breastfeeding. Products should be stored out of the reach of children and pets, for whom even small quantities relative to body weight can be a medical emergency, and in their original labelled containers so that the contents are never mistaken for something else. People vary widely in their response to the same amount, and a person with no tolerance is not comparable to a regular user. None of these points change the arithmetic on this page, and the arithmetic on this page changes none of them.
Legality varies, and arithmetic does not travel
The legal status of a THC tincture depends entirely on where a person is. Some countries, states, and provinces permit adult recreational use, others permit medical use only under prescription or registration, and in many jurisdictions possession is a criminal offence. Age limits, possession limits, and rules about where products may be used differ between these places, and a product that is legal where it was bought does not become legal anywhere else by virtue of that purchase; moving cannabis products across national borders is an offence in most circumstances, including between two jurisdictions that each permit it. This calculator is published for readers in places where such products are lawful, as a label literacy tool. Nothing on the page is a statement about the law anywhere, and anyone unsure of their position should check the rules that apply where they are.
Unlabelled and homemade preparations
Everything on this page rests on knowing the total THC in the bottle, and that figure is reliable only when it comes from laboratory testing of the finished product, which is what licensed labelling represents. A homemade preparation has no such figure: the starting plant material varies in strength, extraction into oil or alcohol is partial and uneven, and the resulting liquid can vary in concentration from the top of the container to the bottom. Typing an estimated total into this calculator produces an exact looking answer built on a guess, and the precision of the output says nothing about the accuracy of the input. For unlabelled preparations the honest statement is that the concentration is unknown, and the arithmetic cannot fix that.
Sources
- United States Centers for Disease Control and Prevention, cannabis health effects guidance: edible and ingested cannabis products have delayed onset and longer lasting effects compared with smoking, and cannabis use is advised against during pregnancy and breastfeeding.
- Health Canada, consumer information on cannabis: effects of eating or drinking cannabis can take 30 minutes to 2 hours to begin and can last up to 12 hours; do not drive after use; combining cannabis with alcohol increases impairment.
- Pharmacopeial convention for the standard medicine dropper: 20 drops of water delivered per millilitre, used on this page as the stated approximation for drop size.
Key takeaways
- Divide the total milligrams of THC printed on the label by the volume of the bottle in millilitres.
- Using the conventional standard of 20 drops per millilitre, one drop holds the milligrams per mL divided by 20.
- No.
- Swallowed cannabinoids act much more slowly than inhaled ones.
Frequently asked questions
How do I work out the milligrams of THC per millilitre of a tincture?
Divide the total milligrams of THC printed on the label by the volume of the bottle in millilitres. A bottle labelled 1000 mg in 30 mL contains 1000 divided by 30, which is about 33.3 mg per mL. Every further figure, including milligrams per drop and the volume that holds a chosen amount, follows from that one concentration.
How many milligrams of THC are in one drop?
Using the conventional standard of 20 drops per millilitre, one drop holds the milligrams per mL divided by 20. For a 33.3 mg per mL tincture that is about 1.7 mg per drop. This is an approximation, not a measurement, because real droppers deliver drops of different sizes depending on the dropper opening, the liquid, and how the dropper is held. A dropper with printed millilitre markings is more reliable than counting drops.
Does this calculator tell me how much THC to take?
No. This page does arithmetic only. It converts the numbers on a product label into other units so the label is easier to understand, and it makes no recommendation about how much anyone should take. How much is appropriate, if any, depends on the person, the product, and the law where they live, and it is a question for the product's own directions and, where relevant, a clinician.
How long does a THC tincture take to work compared with smoking?
Swallowed cannabinoids act much more slowly than inhaled ones. Health Canada advises that the effects of eating or drinking cannabis can take from 30 minutes to 2 hours to begin and can last up to 12 hours, and the United States Centers for Disease Control and Prevention notes that edible products have delayed effects that last longer than the effects of smoking. A tincture held under the tongue may begin to act sooner than one that is swallowed straight away, because some is absorbed through the lining of the mouth, but a swallowed portion still has to pass through the stomach and liver.
Why does tincture strength feel different between products with the same milligrams?
The milligram figure describes how much THC is present, not how the body handles it. Absorption differs between products and people, a swallowed dose is partly converted in the liver to another active compound, and a person's tolerance changes the effect of the same amount. Two products with identical labels can therefore feel different, which is one reason this calculator reports amounts and never predicts effects.
Is a THC tincture legal where I live?
It depends entirely on the jurisdiction. Cannabis products are legal for adults in some countries, states, and provinces, restricted to medical use in others, and illegal in many places, with different age limits and possession rules in each. Legality where the product was bought does not carry across borders, and travelling with cannabis products can be an offence even between two places where each allows it. Check the law that applies where you are.