The fastest way to compare two jars on a dispensary menu is to ignore the sticker price and work out the cannabis price per gram. Divide what you pay by the number of grams in the package, and you get one number that lines every option on the shelf up against every other one. An eighth at $25 works out to $7.14 a gram. A quarter at $42 works out to $6.00 a gram. Same shelf, same afternoon, and one of them is about 16% cheaper per gram than the other.
That is the whole trick, and it takes four seconds on your phone. Below are seven checks we walk neighbors through at the counter at 359 Court St: the weights worth knowing by heart, how Illinois tax moves the number, when price per gram is the wrong measure entirely, and where the savings hide.
How to calculate cannabis price per gram
Price divided by grams. That is it. The only thing that trips people up is remembering how many grams are in the names we all use, so start here:
- 1 gram — a single pre-roll or a one-gram jar
- 3.5 grams — an “eighth,” meaning an eighth of an ounce
- 7 grams — a “quarter”
- 14 grams — a “half ounce”
- 28 grams — an “ounce”
Once those five numbers are in your head, every price tag on the Pekin’s Local menu becomes comparable. A $21 eighth is $6.00 a gram. A $59 half ounce is $4.21 a gram. You stop comparing package sizes and start comparing one honest number.
| Package | Grams | Example shelf price | Cannabis price per gram |
|---|---|---|---|
| Single jar or pre-roll | 1 g | $12 | $12.00 |
| Eighth | 3.5 g | $25 | $7.14 |
| Quarter | 7 g | $42 | $6.00 |
| Half ounce | 14 g | $59 | $4.21 |
| Ounce | 28 g | $109 | $3.89 |
1. Run the number after tax, not before
Shelf prices in Illinois are pre-tax, and cannabis carries more than the usual sales tax. The Illinois Department of Revenue sets a Cannabis Purchaser Excise Tax of 10% on cannabis other than infused products with adjusted delta-9 THC at or below 35%, 25% when it is above 35%, and 20% on cannabis-infused products. On top of that sits the combined sales tax, which in Pekin comes to 14.5% on adult-use purchases — we broke the whole receipt down in our guide to how Illinois cannabis tax works.
So most flower lands about 24.5% above the shelf price by the time you walk out. That $25 eighth is $31.13 out the door, which is $8.89 a gram, not $7.14. The ranking between two jars usually holds — but the gap between categories does not, which is why the next few checks matter.
2. Bigger packages usually win, but look at the step
Larger weights almost always carry a lower cannabis price per gram, and the drop is steeper than most people expect. Walk it down: $25 for 3.5 grams is $7.14 a gram; $42 for 7 grams is $6.00; $69 for two 7-gram jars is $4.93; a 28-gram bundle at $109 is $3.89. That last one is roughly 45% less per gram than the eighth.
The catch is that flower is perishable. An ounce is only a bargain if it is still good at the bottom of the jar, so size up to the weight you will actually finish and keep it properly — our notes on how to store cannabis cover the container and humidity that keep it from drying out.
3. Price per gram is the wrong tool for edibles and drinks
Nobody buys a gummy by the gram, so cannabis price per gram is the wrong yardstick here. For edibles and drinks, the comparable unit is milligrams of THC, so divide the price by the total milligrams in the package and then multiply by ten to get a price per 10 mg serving.
A $20 package holding 100 mg is $2 per 10 mg serving before tax. Infused products carry the 20% excise rate, so after tax that package is $26.90 and each serving costs about $2.69. Run that across two brands and the cheaper box on the shelf is frequently the dearer one per serving.
4. Concentrates and vapes are taxed on a different line
This one quietly changes your cannabis price per gram. Illinois does not classify concentrates and vape cartridges as cannabis-infused products, so they are taxed by adjusted THC level rather than at the flat infused rate — which in practice usually means the 25% bracket, not 20%.
A $30 gram of concentrate is therefore about $41.85 out the door. That is your real price per gram, and it is the number to use when you are weighing a gram of concentrate against an eighth of flower.
5. A high THC number is not the same as value
Two jars at the same cannabis price per gram can be very different buys, and the percentage on the label is a weak guide to which is which. Terpenes, freshness and harvest date show up in the jar long before the THC figure does — we get into that in indica vs sativa vs hybrid and in our guide to shopping by flavor.
There is a pricing wrinkle too. Because the excise rate steps up above 35% adjusted THC, the jar with the biggest number on the front can cost you more per gram twice over: once on the shelf and once at the register.
6. Read the bundles before the single jars
Multi-packs are where the cannabis price per gram falls off a cliff. Mix-and-match sets, two-jar bundles and pre-roll multi-packs are priced as a group, so the arithmetic that looks fussy on a single jar pays best here. Our weekly deals rotate often enough to be worth a look before you pick anything off the main menu.
7. Count your points as part of the price
Points lower your effective cannabis price per gram, so they belong in the math. Pekin’s Local Rewards is free to join and gives you 8 points for every $1 you spend before tax, with up to 1,000 bonus points to start — 500 the moment you join and 500 more for joining the text list.
Every 1,000 points is $5 off, in $5 steps, all the way up to $40 off at 8,000 points, with a minimum purchase of double your reward. Tiers move you up from Local at 8 points per $1 to Marigold at 10 points per $1 (3,000 points, roughly $375) and Court Street at 12 points per $1 (8,000 points, roughly $1,000). Members earn 2× during Happy Hour, Wednesday through Sunday from 11 AM to 1 PM and 4 PM to 6 PM, 2× on flower and pre-rolls on Mondays and 2× on extracts and edibles on Tuesdays — one 2× at a time, they never stack. Rewards are dollars off retail purchases, never product at no cost, and you need to be 21+ with valid government-issued ID. Veterans, seniors and birthdays are handled at the counter too — just ask.
Know the Illinois limits before you size up
There is a ceiling on how much any of this math can buy at once. Per the state’s own cannabis FAQs, Illinois residents over 21 may possess 60 grams of flower (about two ounces), 1,000 milligrams of THC in an infused product and 10 grams of concentrate. Visitors from out of state are held to half of each. Our rundown of Illinois dispensary purchase limits walks through how the three buckets interact in one basket.
If you want the regulatory side of all this rather than the shopping side, the team at Cannabis Industry Lawyer writes about how Illinois structures its cannabis tax and licensing rules, and Cannabis Legalization News tracks the changes as they happen.
Frequently asked questions
How do you calculate cannabis price per gram?
Divide the price of the package by the number of grams it contains. A $25 eighth holds 3.5 grams, so $25 ÷ 3.5 = $7.14 per gram. For a true comparison, use the out-the-door price after excise and sales tax rather than the shelf price.
Is an ounce always cheaper per gram than an eighth?
Almost always on the arithmetic, often by 40% or more. Whether it is cheaper in practice depends on finishing it while it is still fresh, since flower degrades in storage.
Does Illinois tax change the price per gram?
Yes. Excise tax runs 10% on flower at or below 35% adjusted THC, 25% above that line and 20% on infused products, and Pekin’s combined sales tax on adult-use purchases is 14.5%. Flower typically finishes about 24.5% above the shelf price.
How do you compare edibles, which are not sold by the gram?
Use price per 10 mg of THC instead. Divide the package price by the total milligrams, then multiply by ten. It is the same idea as price per gram, just in the unit that edibles are actually measured in.
Come see us on Court Street
Bring your questions and your phone calculator. We are at 359 Court St in downtown Pekin, open daily 10:00 AM to 9:00 PM, at (309) 620-0778. Our budtenders will do the cannabis price per gram math with you at the counter — a better use of five minutes than guessing.
For adults 21+ only. Consume responsibly. Valid government-issued ID required.