There is no universal "one teaspoon" answer. This calculator uses the site ratio for the tea you picked, then scales it to your actual vessel:
vessel ml × grams per 100 ml ÷ 100, rounded to 0.1 g.
That means a 100 ml gaiwan, a 150 ml tasting pot, and a 250 ml mug all get different leaf amounts from the same tea preset. Change the vessel and the grams follow.
Quick examples from the current presets
| Tea preset | Ratio used | 100 ml | 150 ml | 250 ml |
|---|---|---|---|---|
| Green, herbal, matcha | 3 g / 100 ml | 3 g | 4.5 g | 7.5 g |
| Black, white | 4 g / 100 ml | 4 g | 6 g | 10 g |
| Oolong, sheng puerh, shu puerh | 5 g / 100 ml | 5 g | 7.5 g | 12.5 g |
Presets come from each tea type's recommended ratio on this site — the same numbers in the first-party brewing data table — so the result matches the guides instead of drifting into a separate calculator rule.
See it in context in the shu puerh tablet guide, or check how much tea to use per cup for the rationale behind the numbers. If the result still tastes weak or too strong, use the bad-tea troubleshooting guide and change one variable at a time.