A cannabis scale that weighs ounces needs two things: an ounce readout and enough capacity to hold 28 g of flower plus its container. Look for 0.01 g (0.001 oz) resolution and a capacity of 100 g or more. Kitchen scales that read only in 1 g or 0.1 g steps cannot confirm an eighth or a quarter at the precision buyers expect.
Ounce math on a cannabis scale
One avoirdupois ounce equals 28.3495 g. Retail cannabis rounds that to 28 g. The weights you will check most often:
- Eighth: 3.5 g
- Quarter: 7 g
- Half: 14 g
- Ounce: 28 g
If the display is set to troy ounces, a 28 g ounce reads about 0.90 ozt instead of 1.00 oz. Troy ounces measure 31.1035 g and belong to precious metals, not flower. Confirm the unit symbol before you trust a reading.
Specs that matter
- Resolution: 0.01 g for flower. A 0.001 g model is for concentrates and costs more.
- Capacity: 100 g minimum, 200 g to 500 g if you weigh flower inside a jar.
- Units: grams and avoirdupois ounces, with a toggle that holds the setting after the scale powers off.
- Tare: subtracts the container weight so the display shows flower only.
- Calibration: a 100 g or 200 g test weight in the box, or a menu that accepts one.
- Platform: a lid that flips into a tray keeps trim and shake off the counter.
How to set up and verify a new scale
- Set the scale on a hard, level counter away from vents, windows, and running appliances.
- Install fresh batteries or charge by USB, then press power and wait for the zero reading.
- Cycle to ounce mode and confirm the display shows 0.000 oz or 0.00 oz with nothing on the platform.
- Place the empty container on the platform and press Tare.
- Add a known mass to check accuracy: a 100 g calibration weight, or four U.S. nickels for a 20 g test.
- Repeat the check at 10 g, 50 g, and 100 g to catch errors that grow with load.
- Recalibrate if any reading is off by more than one display step at that range.
A U.S. nickel has a standard mass of 5.000 g. Four stacked should read 20.00 g in gram mode. This check does not replace a certified test weight, but it catches a scale that has drifted by a gram or more.
When a certified scale is required
Personal-use scales need no certification. Any scale used to price a retail sale does. Dispensaries and processors in regulated states must use NTEP-certified devices that meet the tolerances in NIST Handbook 44, and inspectors compare them against state weights and measures rules. Putting a $20 pocket scale on a licensed counter creates a compliance problem that costs more than the scale.
Convenience features worth the extra cost
- Backlit display for dim rooms
- Auto-off that waits 3 minutes or longer, since short timers zero out mid-weigh
- Memory that returns to the last unit after a power cycle
- USB-C charging instead of coin cells
- A hard cover that doubles as a weighing tray
Convenience decides which scale stays on the counter. Accuracy decides whether the number on it means anything. Buy for the second, then pick the model that makes the first simple.