Buying task · Scales and weighing
Scales and weighing
Why weighing dose and yield matters, what 0.1 g readability does and does not tell you, and which scale features are worth having at home.
Short answer
A scale lets you weigh the coffee going in and the espresso coming out, so you can repeat a good shot or change one thing at a time. Look for 0.1 g readability, a built-in timer and a footprint that fits on your drip tray. Readability is not accuracy: Acaia's manual for its Lunar scale lists readability, repeatability and linearity as separate specifications.[1]
Why weigh
Weight is the number that ties a recipe together. In Socratic Coffee's controlled tamping study, which used 20 g of coffee for 40 g of espresso, the brew weight drove the differences in strength (TDS), while tamping force did not.[2] A built-in timer adds the other number worth noting, the shot time.
Dose, yield and ratio
- Dose: the ground coffee in the basket, in grams.
- Yield: the espresso in the cup, in grams.
- Brew ratio: yield divided by dose. 18 g in and 36 g out is 1:2.
A 1:2 ratio is a common starting point, not a rule. Cafelat, for example, gives 16 g in and 32 g out for its Robot.[3] The ratio calculator does the arithmetic for any dose and ratio, in either direction.
A simple weighing routine
- Weigh the dose. Put the empty portafilter or dosing cup on the scale, tare it, and grind until you reach your dose.
- Tare the cup. Put your cup on the scale under the portafilter and zero it.
- Start the shot and the timer together.
- Stop at your target yield, then note the weight and the time.
Keep a note of each shot's dose, yield and time. When a shot tastes off, you can then change one of the three and see what happened.
What the specifications mean
| Specification | What it tells you | Acaia Lunar, as an example[1] |
|---|---|---|
| Readability (resolution) | The smallest step the display shows | 0.1 g (0.01 g in a high-resolution mode) |
| Repeatability | How closely repeated weighings of the same item agree | 0.1 g |
| Linearity | How far readings stray across the weighing range | 1 d, one 0.1 g step |
| Capacity | The most it can weigh | 2000 g |
| Battery life | Use between charges | 30 to 40 hours |
If a listing gives a single "0.1 g" figure without saying which of these it is, read it as readability. Accuracy vs resolution explains the difference in more depth.
Water and radios
- Water. Espresso drips. Acaia's Lunar manual gives no water-resistance rating, lists error codes for water in its buttons, and says to clean the scale with a soft cloth and warm water only, without detergent.[1] Treat any scale as splash-sensitive unless its maker states a rating.
- Bluetooth. US rules require devices that intentionally emit radio signals to be certified before they are marketed or imported, with some exemptions.[4] We read a Bluetooth scale as one of those devices. An FCC ID relates to radio rules, not to accuracy or food safety.
How to choose
- 0.1 g readability and a timer cover espresso.
- Measure your drip tray, and the gap between the tray and the bottom of the portafilter. The scale has to fit with a cup on it.
- Capacity matters only if you also weigh larger brews, such as pour-over.
- Rechargeable scales save buying batteries; check the charging port on the listing.
Our scale shortlist has a brand-store pick and a higher-capacity option, each with the variant to order.
Everything in this topic
Guides
- Espresso scale accuracy vs resolutionHelps you read espresso scale specs correctly and check whether your scale is good enough for weighing doses and shots.
Shortlists
- Best espresso scales with a timer and 0.1 g readoutHelps you pick a scale that fits under your portafilter and reads finely enough, while being clear that listing accuracy figures are unverified.
Tools
- Espresso ratio calculatorTurns your dose and chosen ratio into the espresso weight to stop at, or works backward from the yield you want.
Common questions
Do I need a 0.01 g scale for espresso?
No. Makers' example doses run from about 16 to 22 g, so a 0.1 g step is around half a percent of the dose. A scale that repeats its readings matters more than a finer display. More in Espresso scale accuracy vs resolution
What does repeatability mean on a scale spec?
How closely the scale gives the same reading for the same load, time after time. Acaia's Lunar manual, for example, lists 0.1 g repeatability alongside 0.1 g readability. More in Espresso scale accuracy vs resolution
Is my espresso scale waterproof?
Only if its maker gives a water-resistance (IP) rating. Acaia's Lunar manual gives none and lists error codes for water in its buttons, so do not assume a coffee scale is waterproof. More in Espresso scale accuracy vs resolution
Does an FCC ID mean a scale is safe?
No. US rules require radio transmitters to be certified before they are marketed, which we read as covering Bluetooth scales. An FCC ID is not a food-safety or quality mark. More in Espresso scale accuracy vs resolution
Why weigh the shot as well as the dose?
Because output weight changes strength. In Socratic Coffee's tamping experiment, brew weight, not tamp force, drove the differences in TDS. More in Espresso scale accuracy vs resolution
Is 0.1 g resolution enough for espresso?
Yes for home use. At the 18 g dose Breville gives for the Bambino, one 0.1 g step is about half a percent. Remember that resolution is not accuracy: Acaia lists readability, repeatability and linearity separately. More in Best espresso scales with a timer and 0.1 g readout
Why weigh the shot instead of timing it?
Because the amount of espresso in the cup changes its strength. In Socratic Coffee's tamping study, brew weight, not tamp force, drove the differences in TDS. Time is still worth noting alongside weight, which is why both picks have a timer. More in Best espresso scales with a timer and 0.1 g readout
Are these espresso scales waterproof?
We found no water-resistance rating for either, so wipe spills promptly. Even Acaia's Lunar manual gives no rating and says to clean the scale with a soft cloth and warm water only. More in Best espresso scales with a timer and 0.1 g readout
Questions
What does 0.1 g resolution mean on a coffee scale?
It is the smallest step the display shows. It does not tell you how accurate the scale is: Acaia's manual lists readability, repeatability and linearity as separate specifications.[1]
Do I really need a scale for espresso?
If you want repeatable shots, yes. In Socratic Coffee's tamping study, the weight of the brew drove the differences in strength (TDS), so weighing the shot controls a variable that matters.[2]
Can I use a kitchen scale for espresso?
Yes, if it reads in 0.1 g steps and fits on your drip tray. A scale that reads only whole grams hides changes smaller than 1 g, which is over 5% of the 18 g dose Breville gives for the Bambino.[5]
Is my espresso scale waterproof?
Only if its maker gives a rating. Acaia's Lunar manual gives none, lists error codes for water in the buttons and says to clean the scale with a soft cloth and warm water only. Wipe spills promptly.[1]
Does an FCC ID mean a Bluetooth scale is safe?
No. US rules require devices that intentionally emit radio signals to be certified before they are marketed; an FCC ID relates to that, not to food safety or accuracy. See buying and safety.[4]