The right V60 grind is medium-fine, somewhere between table salt and coarse sand. Visually, the particles should be slightly smaller than what you would use for a drip machine, but coarser than espresso.
Use brew time as your guide
A typical V60 with 18g of coffee and 290g of water should finish in 2:45 to 3:15. If your brew finishes in under 2:30, your grind is too coarse, water is rushing through. Grind finer. If it takes more than 3:30, you are choking the bed. Grind coarser.
Start medium, adjust by taste
Begin at your grinder’s manufacturer-suggested V60 setting, or roughly 18-20 clicks from zero on a stepped grinder. Brew. If the cup tastes sour and thin, your grind is too coarse and the coffee is underextracted. If it tastes bitter and dry, you have gone too fine. Adjust one or two clicks at a time and stick with the same coffee for at least three brews.
Why grinder model matters
There is no universal grind setting that works across all grinders. Setting 15 on a Baratza Encore is not the same as setting 15 on a Comandante. Once you find the right setting for your grinder and a specific bean, write it down. The next bag of the same coffee will likely sit within one click of that setting.
One useful habit: grind a small test amount and rub it between your fingers. If it feels gritty like sand, you are close to V60 territory. If it feels powdery, too fine. If it feels chunky, too coarse.