How long does an eighth last?
Use the calculator to estimate how many days a bag of flower may last based on its weight and your usual daily amount.
Short answer: A 3.5 gram eighth lasts about 14 days at 0.25 gram per day, 7 days at 0.5 gram per day or 3 to 4 days at 1 gram per day. Your real result depends on how accurately you measure and how consistent your routine is.
Flower duration calculator
Choose the amount you actually use, not the amount you hope to use. A small scale gives a better estimate than visual guesses.
At 0.5 gram per day, a 3.5 gram eighth may last about one week.
Common eighth estimates
These examples use simple division. They do not recommend a dose or predict an individual experience.
Quick duration chart
| Daily amount | 3.5g eighth | 7g quarter | 14g half | 28g ounce |
|---|---|---|---|---|
| 0.25g per day | 14 days | 28 days | 56 days | 112 days |
| 0.5g per day | 7 days | 14 days | 28 days | 56 days |
| 1g per day | 3.5 days | 7 days | 14 days | 28 days |
| 2g per day | 1.75 days | 3.5 days | 7 days | 14 days |
Why your eighth may last longer or shorter
How you measure
Eyeballing flower can produce inconsistent estimates. Weighing it makes the calculator more useful.
Your routine
Weekends, travel, shared use and changing habits can move actual use above or below a daily average.
Waste and storage
Spills, stale flower and poor storage reduce the usable amount even though they are not part of the calculation.
The estimate is planning information
This tool divides bag weight by the daily amount selected. It does not recommend increasing use, establish a safe dose or predict effects. Start with product-label guidance and avoid driving after using THC.
Choosing a size without overbuying
Try the strain first
A smaller size can make sense when you are still evaluating the aroma, cure and current batch.
Calculate realistic time
Use your measured daily average. If a bag would take months to finish, consider freshness and storage before buying it.
Review the COA
Check the product name, batch details and current laboratory information before making a decision.
Shop with a plan
Compare current indoor THCA flower, available sizes and linked batch information.
Shop THCA flowerCompare flower sizesProtect flower freshness
Frequently asked questions
How long does 3.5 grams last?
At 0.5 gram per day, 3.5 grams lasts about 7 days. At 0.25 gram per day, it lasts about 14 days. Use the calculator for other averages.
How long does a quarter last?
A 7 gram quarter lasts about 14 days at 0.5 gram per day or 7 days at 1 gram per day.
How long does a half ounce last?
A 14 gram half ounce lasts about 28 days at 0.5 gram per day or 14 days at 1 gram per day.
How long does an ounce last?
A customary 28 gram ounce lasts about 56 days at 0.5 gram per day or 28 days at 1 gram per day.
Does an eighth always weigh 3.5 grams?
An eighth is sold as 3.5 grams in the flower market. Visual size varies because bud density and structure vary.
Can I tell how much flower I have by looking?
No. Flower can be dense or airy. A calibrated scale is more dependable than appearance, bud count or container volume.
Keep learning
Editorial review
This guide was reviewed by Chris Garcia, Plenny Owner and CEO. Read our editorial standards for how we separate arithmetic estimates, product information and shopping guidance.
Last reviewed August 12, 2026. Product availability, sizes, pricing and batch information can change. This calculator provides estimates only and is not medical advice or dosing guidance. Adults only. Check current laws before buying, possessing, using or traveling with hemp or cannabis products.
Chris Garcia, Owner and CEO
August 12, 2026
How this page is prepared: Plenny compares available product details and batch COAs with linked primary and reputable sources. General strain, flavor, and effect descriptions are not guarantees.
Commercial transparency: Plenny sells products discussed on this website. Educational pages are not medical or legal advice, and content is not medically reviewed unless a named licensed reviewer is shown.