Matcha keeps showing up in search queries to this site, and the question behind it is fair: this is the one tea where you consume the whole powdered leaf rather than an infusion, so the usual "tea is mostly water" reassurance does not automatically apply. The honest answer requires holding two numbers at once — one from our measured database, one from third-party analyses — and understanding why they differ.
Context is what keeps the range readable. The foods that drive calcium oxalate stone risk measure in the hundreds of milligrams per serving; matcha, even at the high end of credible analyses, does not approach them.
| Food | Oxalate (mg) | Serving | Rating |
|---|---|---|---|
| Matcha tea, prepared (our database) | 2 | 1 cup | Safe |
| Matcha, 2 g powder (third-party analysis) | ~13 | 1 serving | Safe |
| Tea, herbal, variety flavors | 5 | 1 cup | Safe |
| Tea, iced, brewed 10 min | 17 | 1 cup | Safe |
| Almonds, raw or dry roasted | 107 | 1/4 cup | Avoid |
| Spinach, boiled or steamed | 493 | 1/2 cup | Avoid |
There is also outcome evidence worth knowing: a study comparing daily green tea drinkers with non-drinkers who had a stone history found no meaningful difference in urinary oxalate, calcium, urate, or citrate — and if anything a trend toward lower urinary oxalate among the tea drinkers. Green tea catechins may bind calcium in the gut in a way that modestly blunts oxalate absorption. That is not a license for unlimited servings; it is evidence that normal consumption sits comfortably inside most stone-prevention diets.
The one pattern that changes the math is repetition. A single matcha serving at either 2 mg or 13 mg is a rounding error next to a spinach side dish. Three to four café-style servings a day, every day, at the higher preparation strength starts to contribute tens of milligrams — still moderate, but no longer negligible for someone with documented hyperoxaluria. The counter-move is the same one that handles every oxalate-bearing food: pair it with calcium. A matcha latte built on dairy milk puts the calcium-and-oxalate binding in the gut to work at the same sitting, which is why the latte form is the friendlier one for stone formers — a rare case where the more indulgent order is the better-structured one.
Matcha fits fine in a stone-aware diet: keep servings to a reasonable count, favor dairy-milk lattes when the option exists, keep water intake doing its volume work, and weigh matcha against the day's real oxalate spenders rather than treating it as one. If your 24-hour urine shows high oxalate and your diet already includes daily matcha at high strength, that is the one scenario where cutting back first is worth discussing with your clinician before blaming the tea.
See how oxalate values are measured and verified on our data methodology page.