Ratio sets the ceiling
There is only so much soluble material in a given quantity of leaf, and a cup cannot contain more of it than the leaf held. If a tea comes out thin, the honest question is whether there was ever enough leaf in the vessel to make it otherwise. Extending the steep in that situation does not add strength so much as it changes the balance of what was extracted, pulling out the later, grippier fraction while the fast sweet fraction has already finished. The characteristic result — simultaneously weak and harsh — is one of the most common complaints about loose leaf tea and one of the most reliably diagnosed. It is an under-leafed cup, not an under-steeped one.
Why the ratio is expressed in grams per hundred millilitres
Tea is dosed by mass and served by volume, so the useful unit joins the two. Grams per 100 ml is the convention used throughout this catalogue because it makes styles comparable without implying they convert. A spoon cannot do the same job: leaf density varies enormously, and a level spoon of tightly rolled oolong and a level spoon of fluffy white tea can differ several times over in grams. That is not a small discrepancy to be corrected by eye, it is the difference between a good cup and an undrinkable one, and it is the reason the same instruction on two packets produces two completely different results.
Raising the ratio is not the same as extending the time
More leaf in the same water and the same leaf in the same water for longer both make a darker cup, and they do not make the same cup. More leaf puts more of everything that has extracted so far into the same volume of water, keeping the proportions roughly where they were. More time moves further along the extraction sequence, so the proportions shift towards the later fraction. This is why a strong short steep and a weak long steep taste different even when they match for colour, and it is the whole reason the short-steep styles exist. If you want more intensity without more grip, add leaf. If you want more grip, add time — though you rarely do.
Ratio and vessel size are one decision
A ratio is meaningless without a volume, and the volume is usually decided by the vessel that happens to be in the cupboard. A very large teapot pushes you towards a low ratio and a long single steep, because filling it at a high ratio would take an uneconomic amount of leaf. A small vessel makes a high ratio affordable and short steeps natural. This is why the advice to buy a smaller teapot is more consequential than it sounds: it is not about the size of the drink, it is about which brewing style the object makes convenient. Most people brew whatever their equipment makes easy.
What ratio cannot fix
It cannot rescue water that was too hot for the tea, because that error changes which compounds came out rather than how many. It cannot compensate for leaf that has no room to expand: a packed infuser basket wets only the outside of the clump, so raising the dose in a cramped basket adds cost without adding extraction. And it cannot correct stale leaf, which has lost aromatics that no quantity of it will put back. Ratio is the strongest lever available, and like every strong lever it is useless when the problem is somewhere else entirely.
Finding yours
Start from the tea’s own recorded parameters for the method you are using, brew it, and then move in one direction only. If the result is thin, add leaf rather than time. If it is heavy and grippy, cut the time before you cut the leaf, because a shorter steep at the same dose usually keeps the sweetness a lower dose would lose. Keep the water the same while you do this. Two or three sessions of single-variable adjustment will land you somewhere you could not have got to from a packet instruction, and the habit transfers to every tea afterwards.