Quick answer: To read a Maine cannabis label, find four things: total THC (a percentage on flower and vapes, milligrams per serving and per package on edibles and drinks), the batch number, the production date and the words "Passed mandatory testing." Under the Office of Cannabis Policy's 2024 rules, an edible serving tops out at 10 mg of total THC and a package at 200 mg.
Everything else is a warning, a license number or the brand's own story. The rules behind all of it sit in Title 28-B section 701 and the Office of Cannabis Policy's chapter 30 Compliance Rules, which replaced the old chapter 1 rule on November 6, 2024.
What has to be on every Maine cannabis label?
Every adult use package sold in Maine has to show the store's license number, the full Metrc batch number from the tested batch, net weight, a production date, cannabinoid content, the universal symbol, and the words "Passed mandatory testing." All of it has to sit on the outer package (the rules call it the marketing layer) in type no smaller than 6 point.
Every package also carries the same general warning, word for word: "WARNING: Keep out of reach of children and pets. Do not drive or operate machinery while intoxicated. This product can be addictive. Use of this product may be harmful, especially if you are under 21, inexperienced with cannabis, pregnant, breastfeeding, or at risk for psychiatric problems."
Two louder 12 point warnings appear only when they apply: "WARNING: PACKAGE IS NOT CHILD RESISTANT" and "WARNING: PACKAGE IS NOT TAMPER EVIDENT." If you see either one, the store has to put your purchase in a child-resistant, tamper-evident exit bag. Our post on keeping your stash away from curious kids covers home storage.
The universal symbol
The symbol is a red triangle with a black cannabis leaf on white and the words "CONTAINS THC." Maine shares it with Massachusetts. It has to be at least half an inch square on the front of the package. On edibles, each serving has to be stamped with it or individually wrapped with it, except for products the law treats as impractical to mark, such as gummies, popcorn and chips, which can share one marked package.
Three labels, taken apart field by field
These are invented composites built to match the rules.
| Field | Flower (3.5 g jar) | Gummies (20 pieces) | THC drink (12 oz can) |
|---|---|---|---|
| Potency format | Total THC 22.4%, total CBD 0.1% | 5 mg THC per piece, 100 mg per package | 5 mg THC per can |
| Net weight | 3.5 g (may run 0.1 g under or 0.5 g over) | Gummies only, no packaging | Drink contents |
| Production date | Harvest date | Batch manufacture date | Batch manufacture date |
| Batch number | Metrc ID of tested batch | Same | Same |
| Packaging | Child-resistant jar or exit bag | Resealable child-resistant container | Child-resistant cap or crown cap |
| Extra statements | "Contents have been treated with [method]" if remediated | "This product contains cannabis. Keep away from children." | Same two edible statements |
| Onset warning | None | "Effects of this product may not be felt for up to 4 hours." | Same |
Flower potency has to be the actual total THC and CBD result from the lab's certificate of analysis, not a flattering range. The treatment line is the one shoppers skip: it tells you the flower was remediated for mold or microbes, by ozone or radiation for example. That's legal, and worth knowing.
The drink is the sneaky one. It reads like a soda and gets labeled like a gummy, because Maine treats cannabis drinks as edibles. Gas station versions follow different rules entirely; see hemp THC drinks versus dispensary THC drinks.
How do you turn THC percent into milligrams?
Multiply the weight in milligrams by the percentage. One gram is 1,000 mg, so a gram of flower testing at 22.4% total THC holds about 224 mg of total THC. The full 3.5 g jar holds about 784 mg.
That's what's in the plant, not what reaches you. Some burns off, some drifts away as smoke, and the rest depends on the device and the person. Anyone quoting you a precise figure for your joint is guessing.
Use the math to compare, not to dose. A 28% jar has about a quarter more THC per gram than a 22% jar, which is worth knowing before you pack a bowl the way you used to. Percent says nothing about aroma, though; terpenes such as myrcene tell that story.
Milligrams per serving versus per package
Per serving is your dose; per package is the whole bag. Maine edible labels show both plus the serving count, so it's division: 100 mg per package across 20 pieces is 5 mg a piece.
The limits, from chapter 30 and Title 28-B section 703:
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A serving can hold no more than 10 mg of total THC.
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A package can hold no more than 200 mg of total THC. (Older guides still say 100 mg. That changed.)
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Single-serving drinks and tinctures stay at or under 10 mg.
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Multi-serving drinks between 10 mg and 200 mg need a resealing child-resistant cap and a real measuring device. Hash marks printed on the bottle don't count.
The printed number has a tolerance: 10% either way for edibles at 5 mg or more, 20% below 5 mg. So a 5 mg gummy can legally test anywhere from 4.5 to 5.5 mg.
The four hour warning isn't boilerplate either. Read up on how long edibles take to kick in and how long THC drinks take to kick in, since they don't always behave alike.
Total THC versus THCA: what's the difference?
THCA is the acid form of THC that raw flower mostly contains. Total THC is the lab's estimate of how much THC you'd have after heating, and it's the number Maine requires on the front of the label. The formula is written into the rules: total THC equals delta-9 THC plus THCA times 0.877.
The 0.877 is there because THCA loses a bit of weight (a carbon dioxide molecule) when heat turns it into THC. So a certificate of analysis showing 24.0% THCA and 0.8% delta-9 THC works out to 0.8 plus 21.0, or about 21.8% total THC. A jar shouting "THCA 24%" is showing you the bigger number. Total THC is the honest one. Our guide to decarboxylation walks through what heat is doing.
Edibles and drinks use already-heated oil, so the distinction mostly matters on flower and pre-rolls.
What does "Passed mandatory testing" cover?
It means a sample from that batch passed every test in 18-691 CMR chapter 40 at a state-certified lab. Those tests cover potency and homogeneity, pesticides, heavy metals (cadmium, lead, arsenic and mercury), residual solvents, yeast, mold and mycotoxins, harmful microbes including Salmonella and Shiga toxin-producing E. coli, visible filth, and water activity for dried flower and shelf-stable edibles.
The detailed results live on the certificate of analysis, which isn't on the package. Maine allows a QR code linking to it but doesn't require one. The testing rules were also under routine revision in 2026 (public comment closed August 14), mostly around edibles.
What the label doesn't tell you
It's a compliance document, not a buying guide. It won't tell you:
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The terpene profile, unless the brand chose to test for it and print it.
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How the flower was dried and cured, or how it's been stored since the harvest date.
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How it will feel for you. Tolerance, food and sleep all change that.
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A farm story. You get license numbers.
Maine also forbids health or physical benefit claims on labels, so be skeptical of any package that seems to make one. Health questions belong with a healthcare provider.
Bringing a label to our counter on St John Street
Hand any package to a Cannabis Guide at our Portland shop and ask three things. When was this harvested or made? Is the certificate of analysis available, and what did it show for terpenes? What's a sensible first serving of this for someone with my experience? We'd rather spend two minutes on that than have you learn about a 10 mg drink the hard way.
If you're new, what to expect on your first dispensary visit covers ID and payment, and Maine possession and purchase limits keeps your math legal.
Frequently asked questions
What is the THC limit for edibles in Maine?
A single serving of an adult use edible in Maine can contain no more than 10 mg of total THC, and a package can contain no more than 200 mg. Those limits come from Title 28-B section 703 and the Office of Cannabis Policy's chapter 30 rule, effective November 6, 2024. Older articles citing a 100 mg package cap are out of date.
What does total THC mean on a Maine label?
Total THC is the lab's estimate of THC available after heating. Maine's rules define it as delta-9 THC plus THCA multiplied by 0.877, which accounts for the weight THCA loses when it converts. Flower and vape labels must show the actual total THC result from the certificate of analysis, so it is the number to compare between jars.
Do Maine cannabis labels have QR codes?
Sometimes. Maine's chapter 30 rule allows a QR code or other digital link on the package, but it does not require one, and a code never replaces the printed label information. When a brand includes one, it often links to the certificate of analysis. If there is no code, ask the store whether the lab results are available.
What does Passed mandatory testing mean in Maine?
It means a sample from that Metrc batch passed every test required by 18-691 CMR chapter 40 at a state-certified lab. That covers potency, pesticides, heavy metals, residual solvents, yeast and mold, mycotoxins, harmful microbes such as Salmonella, visible filth and, for some products, water activity. Stores cannot label or sell a product that has not passed.
Why does my THC drink say effects may take up to 4 hours?
Maine labels cannabis drinks under the same rules as edibles, and every edible must carry the statement that effects may not be felt for up to 4 hours. Some people report feeling drinks sooner, but timing varies by product and person, so the label plans for the slow case. Wait before reaching for a second can.
To practice on real labels, browse the Rose Mary Jane menu, order ahead for pickup at 327 St John St, and bring your questions with your ID.