How long should you steep tea? A temperature and time window for green, white, oolong, black and herbal
Bitter tea is usually a hot water or long steep problem, and thin tea is the reverse. Each type has a window: green and white like water around 70 to 85°C, black and herbal like it just off the boil.
Pick a tea, then set the water temperature and steep time on the chart to see whether your cup lands in the usual window, runs bitter or comes out thin. It also covers how to cool water without a special kettle, and why more leaf beats a longer steep.
Most tea advice boils down to one line on the box: "use freshly boiled water, steep for three minutes". That is fine for a builder's brew and wrong for a lot of other teas. A delicate green tea in boiling water turns bitter and drying. A black tea in cooler water tastes thin and flat. Two numbers decide most of the cup: how hot the water is and how long the leaf sits in it.
Two dials, one window
Hot water pulls flavour out of the leaf, and it pulls different things at different speeds. Sugars and amino acids (the sweet, savoury, rounded part) come out early. Tannins, the compounds that make tea bitter and dry in the mouth, come out later and much faster in hotter water. So there is a window for each tea: long enough to get the good stuff, short enough to leave most of the harsh stuff behind.
The window is wider for tough, fully oxidised leaves (black tea, many herbal blends) and narrower for young, lightly processed ones (green and white). That is why the usual advice looks like this: green tea in water around 70 to 80°C for one to three minutes, black tea in water just off the boil for three to five.
Find your cup in the window
Pick a tea, then move the two sliders (or tap the chart). The gold box is the common window for that tea. Outside it, the note under the chart says which way the cup is leaning.
Why hot water bites
Bitterness in tea mostly comes from tannins and from caffeine, and both dissolve faster as water gets hotter. That is why a cup that tastes sweet at 75°C can taste sharp at 100°C with the same leaf and the same time. Steeping longer has a similar effect, just more slowly: the longer the leaf sits, the more of the late, drying compounds end up in the cup.
Going the other way, too cool or too short leaves the cup thin. It may taste watery, grassy or faintly sour because the sweeter, rounder compounds have not had time to come out. Under-extraction is less talked about than bitterness, but it is just as common.
Bitter tea is usually a hot-water or long-steep problem. Thin tea is a cool-water or short-steep problem.
No temperature kettle? Do this
You do not need special kit. Boil the kettle, pour the water into the cup or pot and let it stand. A rough rule is that it takes a few minutes in an open mug to fall from boiling to the 70s, but it varies a lot with the size and material of the vessel, so check with a thermometer once and learn your own timing. Pouring the water into a second jug first drops it faster. A common habit is to pour, wait a couple of minutes for a green tea, then add the leaf.
Two other things make a bigger difference than people expect: the amount of leaf (a heaped teaspoon, about 2 g, for a 200 ml cup is the usual start; more leaf with a shorter steep is better than the same leaf for ages) and the water itself. Fresh, cold tap water that has not been boiled several times tastes cleaner, and very hard water can dull delicate teas.
Reading the box
If the pack gives a temperature and time, use it first. It was written for that blend. If it only says "boiling water, 3 minutes", it is probably aimed at a robust black tea, and if it is a green or white tea you can safely try cooler water and a shorter steep and see if you like it better. Taste is the final judge: if you enjoy your green tea strong and a little bitter, that is a perfectly fine cup.
A final note on caffeine: tea generally has less than coffee per cup, but it adds up, and a long, hot steep of a caffeinated tea pulls out more. If you are drinking tea late in the day, a herbal blend is naturally caffeine-free.
What to look for
Whatever you steep with, four things matter. First, a way to get water to the right temperature, whether that is a thermometer, a variable-temperature kettle or just waiting. Second, room for the leaf to open, so a roomy pot or infuser basket beats a tiny ball. Third, a timer, because "about three minutes" drifts to ten when you are not watching. Fourth, a way to stop the steep: lift the infuser or pour the tea off the leaf, rather than leaving it to stew in the pot.