Tea Caffeine Calculator
Tea caffeine mg from cups, type, and mug size.
What it does
Tea caffeine hides behind color. Black runs near 47 mg a cup while green runs near 28 and herbal near zero, so three greens land under two blacks. Cup size multiplies everything: a 12 oz mug carries half again the 8 oz figure.
The tool above totals any tea day. Enter cups, ounces, and type, and it prints milligrams, the share of the 400 mg daily reference, and the brewed-coffee equal. Defaults give 94 mg at 23.5 %, like one coffee.
Federal and clinical sources align. FDA scales black tea at 71 mg per 12 oz (47.3 per 8 oz) with 400 mg a day as the adult reference, and Mayo charts list black 48, green 29, and decaf 2 per 8 oz. A 2008 analytical study found 14 to 61 mg across types with herbal at zero.
Brew habits move real cups off the averages. Long steeps and small leaf teas extract more, while quick white tea steeps land near the 15 mg planning figure. Treat the total as a planning estimate and watch sleep and jitters for the personal verdict.
How to use
- Enter cups of tea per day.
- Enter cup size in ounces.
- Pick the tea type.
- Read total mg first.
- Read the share of 400 mg.
- Compare with coffee cups.
Formula
- cups
- Cups per day, 0 to 50.
- mg/8oz
- Black 47, oolong 38, green 28, white 15, decaf 2, herbal 0.
- 400 mg
- FDA daily reference for healthy adults.
Per-cup figures trace to USDA-linked FDA scaling (71 mg per 12 oz black is 47.3 per 8 oz) and Mayo charts, with lab ranges from Chin et al. 2008.
Worked example
Example: 2 black teas
Defaults: 2 black teas at 8 oz.
- Inputs: 2 black teas, 8 oz each.
- Black runs 47 mg per 8 oz.
- Total: 2 x 47 = 94 mg.
- Share: 94 / 400 x 100 = 23.5 %.
- Coffee equal: 94 / 96 = 1. Tool shows 94 mg, 23.5% of 400 mg, 1 cup coffee.
Reference table
| Type | mg | Cups to 400 mg |
|---|---|---|
| Black | 47 | 8.5 |
| Oolong | 38 | 10.5 |
| Green | 28 | 14.3 |
| White | about 15 | about 26 |
| Decaf black | 2 | 200 |
| Herbal | 0 | no caffeine limit |
Limits
- Planning averages only. Brews range 14 to 61 mg.
- Ignores steep time, leaf grade, and blends.
- 400 mg reference suits healthy adults, not all groups.
- Herbal blends with cocoa or maté differ.
Common mistakes
- Counting mugs as 8 oz cups.
- Treating all teas as equal caffeine.
- Skipping cup size on big mugs.
- Chasing the 400 mg line as a goal.
- Forgetting coffee and soda in the day total.
Try it yourself
Quick checks. Answers sit tucked under each question.
3 green teas at 8 oz?
3 x 28 = 84 mg. 84 / 400 = 21 %. 84 / 96 = 0.9 cups coffee.
2 oolongs at 12 oz?
2 x 38 x 1.5 = 114 mg. 114 / 400 = 28.5 %. 114 / 96 = 1.2 cups.
Questions
How much caffeine per tea type?
Black 47, oolong 38, green 28, white about 15, decaf 2, herbal 0 mg per 8 oz, per USDA-linked FDA and Mayo figures.
How is the total figured?
Cups times mg times ounces over 8. Two 12 oz oolongs: 2 x 38 x 1.5 = 114 mg.
What is the daily reference?
400 mg a day for most healthy adults, per FDA and Mayo Clinic. The tool prints your share of it.
How many cups reach 400 mg?
About 8.5 cups of black tea (400/47). Green needs about 14 cups to match.
How does tea compare with coffee?
Brewed coffee runs about 96 mg per 8 oz. Two black teas equal about 1 coffee.
Does brew strength matter?
Yes. Lab ranges span 14 to 61 mg with no strict trend, so strong steeps run higher than these planning figures.
Sources
- FDA: How Much Caffeine Is Too Much (400 mg, tea figures)
- Mayo Clinic: Caffeine Content Chart (tea and coffee mg)