How to Compare Two Coffee Grinders in a Blind Taste Test

What a fair coffee grinder comparison controls

A fair comparison of two coffee grinders holds every other variable constant: one bag of beans, one roast date, the same dose weighed to 0.1 g, the same water, the same brewer and the same recipe. The grinder comparison also needs both grinders purged first, so old grounds stuck in either grinder do not end up in the test cups. If two variables change at once, a taste difference cannot be credited to the grinder.

Matching grind size between two different grinders

Grind dial numbers do not transfer between grinders, because each grinder's burrs and zero point differ. Match two grinders by the brew result instead:

• Pour-over: adjust each grinder until the same recipe gives the same total drawdown time.
• Espresso: adjust each grinder until the same dose and yield run in the same shot time.
• Cupping: set both grinders coarse, in the range the cupping protocol describes as 70–75% of grounds passing a #20 sieve.

Matching extraction time is not perfect, since flat and conical burrs make different particle spreads, but that spread is exactly the grinder difference the taste test is meant to detect. For what that difference tends to taste like, see flat burr vs conical burr taste difference.

Cupping setup for a two-grinder taste test

Cupping is the cleanest way to compare two grinders, because it removes pouring technique from the test. Royal Coffee's summary of the SCA cupping standard gives these settings:

1. Use 8.25 g of coffee to 150 mL of water, roughly 1:18, in identical cups.
2. Grind each sample immediately before cupping, or cover the cups to hold in aroma.
3. Pour water at 200°F ± 2°F (92.2–94.4°C).
4. Steep for four minutes, then break the crust by pushing the floating grounds back gently.
5. Let the cups cool to around 170°F before tasting, and taste again as they cool further.

Hiding which grinder made each cup

A blind grinder test needs a helper who grinds and brews while the taster is out of the room. The helper marks the bottom of each cup, or keeps a written key, and labels the tops with random three-digit codes, the approach sensory classes use with 3-number codes and a changing serving order. Identical cups, equal fill levels and the same serving temperature keep visual cues out of the grinder comparison.

Running a triangle test on two grinders

A triangle test asks one question: can the taster tell the two grinders apart? The helper serves three coded cups, two from one grinder and one from the other, and the taster picks the odd cup. Rotate the serving order through all six arrangements (AAB, ABA, BAA, BBA, BAB, ABB) across rounds so position gives nothing away.

With no real difference, the chance of picking the odd cup is one in three, and significance comes from an exact one-sided binomial test. Worked out at the 5% level, the grinder triangle test needs:

Rounds	Correct picks needed
6	5
8	6
10	7
12	8

Rinse with water between rounds and cap a session at a few rounds, since palate fatigue lowers accuracy late in a grinder tasting.

Comparing two grinders for espresso in a blind test

An espresso grinder comparison works the same way, but the helper pulls shots from each grinder at the matched dose, yield and time. Serve the shots in identical cups, stir each one so crema does not reveal the grinder, and taste within a minute or two of each other. Log dose, yield and time for every shot on an espresso dial-in sheet, because an off-target shot is a recipe error rather than a grinder result.

Reading the results of a blind grinder taste test

If the taster cannot pass the triangle threshold, the two grinders taste the same in that recipe, and price, workflow and retention should decide the purchase. If the taster passes, run a second round where the taster names which cup is preferred and why, using plain terms like sweetness, clarity and body. The guide to tasting espresso without the bag notes helps put those differences into words. A preference that repeats across roasts is stronger evidence than one bag.

Blind grinder taste test FAQ

How do you compare two coffee grinders fairly?

Change only the grinder. Use the same beans from the same bag, the same dose, water, brewer and recipe, match each grinder to the same brew time or shot time rather than the same dial number, and have a helper code the cups so the taster cannot tell which grinder made which cup.

Can you use the same grind setting number on two different grinders?

No. Grind dial numbers are specific to each grinder's burrs and calibration, so setting 10 on one grinder says nothing about setting 10 on another. Match two grinders by result instead: equal drawdown time for pour-over, or equal shot time for the same dose and yield in espresso.

How many rounds does a blind grinder taste test need?

A triangle test has a one-in-three chance of a lucky guess, so a single round proves little. By an exact binomial test at the 5% level, a taster needs 5 correct out of 6 rounds, 6 of 8, 7 of 10 or 8 of 12 before the difference between two grinders counts as real rather than luck.

Should a blind grinder test use cupping or the normal brew method?

Use cupping to learn whether two grinders taste different at all, because cupping removes pouring technique as a variable. Use your normal brew method to learn which grinder you prefer for the coffee you actually drink every day.

Sources

• Royal Coffee: How to set up and run a coffee cupping
• MetricGate: Triangle test discrimination
• Food Science Toolbox: Sensory evaluation
• Pass thresholds calculated with an exact one-sided binomial test, chance = 1/3, alpha = 0.05.