Cannabis weights explained: gram to ounce
An eighth is 3.5 grams of cannabis flower, or one-eighth of an ounce. Cannabis is sold by weight using a small set of standard amounts: a gram, an eighth (3.5g), a quarter (7g), a half (14g), and an ounce (28g). This guide explains exactly what each amount weighs, how the math works, how the units show up on a label, and what to check before you buy. This is general information, not medical or legal advice.
The five amounts at a glance
Cannabis flower is almost always sold in a handful of standard weights, and once you know them the rest is just multiplication. A gram is the smallest common unit. An eighth is 3.5 grams. A quarter is 7 grams. A half is 14 grams. A full ounce is 28 grams. Each step up the ladder is roughly double the one before it, which is why the names line up so neatly: an eighth is one-eighth of an ounce, a quarter is one-quarter, a half is one-half, and an ounce is the whole thing. You will sometimes see a 2-gram or 5-gram size, but those are less standard and depend on the brand or store. Pre-rolls are a separate case, since a single joint is often packed with 0.5g or 1g and multi-packs are labeled by total weight. Knowing these five numbers covers the vast majority of flower purchases you will ever make, and it lets you compare prices across stores without a calculator.
Why 28 grams, not 30
The ounce in cannabis is the avoirdupois ounce, the same one used for most everyday goods in the United States, and it equals 28.349 grams. In practice the industry rounds it to 28 grams, and every smaller amount is derived from that rounded figure. So an eighth is one-eighth of 28, which is 3.5 grams. A quarter is one-quarter of 28, or 7 grams. A half is 14 grams. The rounding is why a gram-by-gram total of an ounce comes out to 28 exactly rather than 28.35. This is a customary measure, not a metric one, which is why a community built around grams still leans on a unit borrowed from the old imperial system. It can feel confusing at first that the small sizes are metric (grams) while the large size is imperial (the ounce), but the two are simply bridged by that 28-gram convention. Once you accept that an ounce equals 28 grams for buying purposes, all the fractions fall into place and the names stop being mysterious.
The slang you will actually hear
Walk into a shop or read a menu and you will see both the formal weight and a nickname. A gram is sometimes called a dime or a single. An eighth gets the most nicknames of all: an eighth, a slice, a cut, or simply 3.5. A quarter is a quad or a quarter-O. A half is a half-O or half-zip. A full ounce is an ounce, an O, or a zip, the last term widely believed to come from the size of a one-ounce plastic bag. You may also hear larger wholesale terms like a QP, which is a quarter-pound, equal to four ounces or 113 grams, though those are rarely relevant to everyday retail and may exceed legal possession limits where you live. The key point is that the slang always maps back to a real weight. When a menu lists 3.5g and 'eighth' side by side, they mean the same thing, and a price tied to the nickname is a price tied to the grams underneath it.
By volume that is a small handful of buds, though the exact look varies a lot.
How much is an eighth, really
Because it is the question people ask most, the eighth deserves its own breakdown. An eighth is 3.5 grams of flower, which is one-eighth of a 28-gram ounce. By volume that is a small handful of buds, though the exact look varies a lot. Dense, tightly trimmed flower takes up less space than light, fluffy flower of the same weight, so two eighths can look quite different in a jar even though the scale agrees they weigh the same. That is normal and is a function of density, trim style, and moisture, not a sign that one is short. The eighth is popular because it is large enough to be a reasonable buy and small enough to finish before flower dries out and degrades. Many shops price their flower around the eighth as the anchor size, then offer discounts as you move up to a quarter, half, or ounce. If you are sampling a new strain or brand, an eighth is the common starting size, and it gives you enough to form an honest opinion.
The math: converting between units
Every cannabis weight reduces to grams, so conversions are simple arithmetic. There are 3.5 grams in an eighth, 7 in a quarter, 14 in a half, and 28 in an ounce. To go up a level you double, and to go down you halve. Two eighths make a quarter (3.5 plus 3.5 equals 7). Two quarters make a half. Two halves make an ounce. Working the other direction, an ounce contains eight eighths, four quarters, or two halves. If you ever want a per-gram price, divide the total price by the number of grams: an eighth that costs forty dollars works out to about eleven dollars and forty cents per gram, while an ounce at two hundred dollars is closer to seven dollars per gram. Doing that division is the fastest way to see whether a bigger size is actually a better deal. Keep the four base numbers in mind, 3.5, 7, 14, and 28, and you can translate any menu, compare any two prices, and never be caught guessing what a nickname means at the counter.
What a label and package weight mean
Regulated cannabis is sold in labeled packaging, and the net weight printed on it is the producer-stated amount of flower inside, not counting the jar or bag. So an eighth labeled 3.5g should contain 3.5 grams of flower by weight. Labels in regulated markets also carry batch or lot numbers, a packaged-on or harvest date, and the license information of the grower and processor. The weight figure is what you are paying for, and it is set by the producer and verified within the supply chain rather than by BudAbout, which does not weigh or test anything. Small variances can exist because flower loses moisture over time, so a jar packaged months ago may read slightly differently than the day it was sealed. If a package is sealed, you generally cannot reweigh before buying, which is one more reason to buy from licensed retailers who stand behind the stated weight. Treat the printed net weight as the contract: that number, in grams, is the amount you are purchasing.
A heavier purchase is simply more of the same flower, not stronger flower.
Where THC and terpene numbers fit
Weight tells you how much flower you are getting; it says nothing about potency or aroma. Those are separate figures. The cannabinoid percentages, such as a producer-reported THC number, and any terpene results come from the grower or from an accredited testing lab, not from BudAbout, and they appear on the label or on a certificate of analysis. A heavier purchase is simply more of the same flower, not stronger flower. An eighth and an ounce of the same batch carry the same percentage on the label; the ounce just gives you eight times the quantity. It is worth keeping the two ideas in separate boxes in your head: grams answer 'how much,' while the lab figures answer 'what is in it.' We cover potency labeling and certificates of analysis in their own posts, so here it is enough to say that weight and lab results are independent. When you compare products, look at the weight to judge quantity and value, and look at the producer-reported and lab figures to judge what the flower contains.
Pre-rolls, multi-packs, and odd sizes
Not everything is sold in the classic eighth-to-ounce ladder. Pre-rolled joints are sold individually or in packs, and they are labeled by weight too. A single pre-roll commonly holds 0.5g or 1g, and a five-pack of half-gram joints adds up to 2.5 grams total. Infused pre-rolls, which contain concentrate alongside flower, are still labeled by total weight, so read carefully if you are comparing them to plain flower. You will also see brand-specific sizes, such as a 2g or 10g jar, that do not fit the standard fractions, along with bundled deals that mix sizes. None of this changes the underlying rule: the package states a net weight in grams, and that is what you are buying. When a pack lists both a count and a total weight, the total weight is the figure to use for price-per-gram comparisons. Treat pre-rolls and odd sizes the same way you treat loose flower, by converting everything back to grams, and you will always know exactly what is in the package and how it stacks up.
Reading price and value across sizes
Shops usually price flower so that buying more lowers your cost per gram, the same volume-discount logic you see in a grocery store. An eighth has the highest per-gram price, and the rate generally drops as you move to a quarter, half, and ounce. That does not automatically make the ounce the smart buy. Flower is a perishable product, and an amount you cannot finish in a reasonable time may dry out and lose quality before you get to it. The better question is how much you will realistically use while it is fresh, then buy the size that fits. To compare honestly, convert every option to a per-gram price by dividing the total by the grams, and weigh that against how quickly you go through flower. A cheaper ounce that goes stale is not cheaper in practice than two fresh eighths. Sales and bundles can scramble the usual ladder, so always run the per-gram math yourself rather than assuming the biggest size wins. Value is the intersection of price per gram and how fast you will actually use it.
Cannabis is sensitive to air, light, heat, and humidity, all of which can dry it out or degrade it over time.
Storing what you buy so weight holds up
The weight you pay for is most meaningful when the flower stays in good condition, and storage is what protects it. Cannabis is sensitive to air, light, heat, and humidity, all of which can dry it out or degrade it over time. An airtight container kept in a cool, dark spot helps flower hold its quality longer than an open bag on a sunny shelf. Glass jars are a common choice, and some people add a humidity-control pack sized for the amount they are storing to keep moisture steady. Because flower loses water weight as it dries, a buds-on-a-scale total can drift slightly over weeks, which is normal and not a sign you were shorted at purchase. This is one practical reason the larger sizes are not always the bargain they look like: an ounce that sits for months may not be as fresh as a smaller amount bought and used promptly. Buying a size you will finish while it is fresh is the simplest way to make sure the grams you paid for are grams you actually enjoy.
Legal limits and buying smart
How much you can legally buy or possess at one time is set by state and local law, not by the shop's menu, and the limits differ from place to place and change over time. In many regulated markets the everyday retail limits land in the range of an ounce of flower per transaction, but the exact figure, and how concentrates or edibles count toward it, depends entirely on your jurisdiction. Larger quantities like a quarter-pound are often outside personal possession limits, which is another reason those wholesale terms rarely appear on a retail menu. Always buy from a licensed retailer, keep your purchase within your local limit, and remember that this is general information, not legal advice. If you are unsure what applies to you, check your state's current rules or ask the licensed shop directly, since staff there work within those limits daily. Knowing the weights is half the picture; knowing the legal ceiling on those weights where you live is the other half, and the two together let you buy with confidence and stay on the right side of the rules.
A quick buyer's checklist
Before you decide on a size, run through a short mental list. First, fix the five base weights in mind: gram, eighth at 3.5g, quarter at 7g, half at 14g, ounce at 28g. Second, decide how much you will realistically use while the flower stays fresh, and let that guide the size rather than the discount. Third, convert each option to a price per gram by dividing total cost by grams, so you are comparing like with like. Fourth, read the package net weight and confirm it matches the size you are buying, and note the packaged or harvest date. Fifth, remember that potency and terpene figures are producer-reported or lab-measured and are separate from weight. Sixth, stay within your local legal limit and buy from a licensed retailer. Run that list and you will rarely overpay or over-buy. None of this requires special knowledge, just the four anchor numbers and a little arithmetic, and once it becomes habit you can size up any menu in seconds. This is general information, not medical or legal advice.
FAQ
How much is an eighth?
An eighth is 3.5 grams of cannabis flower, which is one-eighth of a 28-gram ounce. It is the most common starting size because it is large enough to be worthwhile but small enough to finish while fresh. Stores often price flower around the eighth as the anchor size.
How many grams are in an ounce?
An ounce of cannabis is 28 grams for buying purposes. Technically the avoirdupois ounce is 28.349 grams, but the industry rounds to 28. That rounded figure is why an eighth is 3.5g, a quarter is 7g, and a half is 14g, since each is a fraction of 28.
What is a quarter and a half in grams?
A quarter is 7 grams, or one-quarter of an ounce, and a half is 14 grams, or one-half of an ounce. Two eighths make a quarter, and two quarters make a half. Each step up the ladder is roughly double the previous amount, which keeps the math simple.
Why does an eighth sometimes look bigger or smaller?
Because flower density and moisture vary, two eighths of the same weight can look different in a jar. Dense, tightly trimmed buds take up less space than light, fluffy ones. The scale, not the eyeball, settles the weight, so a 3.5g label means 3.5 grams regardless of how it looks.
Does buying a larger size mean stronger flower?
No. Weight is quantity, not potency. An eighth and an ounce from the same batch carry the same producer-reported percentage on the label; the ounce is simply eight times more flower. Potency and terpene figures come from the grower or an accredited lab and are separate from weight.
Is a bigger size always a better deal?
Per gram, larger sizes usually cost less, but flower is perishable and can dry out before you finish it. To compare honestly, divide each price by its grams, then weigh that against how fast you will use it. A fresh eighth can beat a stale ounce. This is general information, not legal advice.