In short
- A dollar threshold means something different on every pair, so it cannot be set once.
- Denominating in BTC gives a single number that reads the same across markets.
- Quote groups matter: a sensible threshold against BTC is not a sensible one against USDT.
- Building the ladder from real percentiles beats round numbers.
- BTC is a unit of account here, not a prediction that BTC keeps its price.
Every alerting tool eventually faces the same design question: in what unit does the user express “big”? The default answer is dollars, because dollars are familiar. It is also the answer that guarantees the user will need a different threshold for every coin.
Why a dollar threshold cannot be set once
Trade sizes are not distributed alike across pairs. On BTC/USDT, six-figure prints are routine. On a mid-cap altcoin, one may be the largest trade of the day. On a small-cap, it might not be possible at all without moving the price several percent.
So a single dollar figure produces three different behaviours at once:
- On majors — constant firing, because that size is ordinary.
- On mid-caps — occasionally useful, by luck.
- On small-caps — permanent silence, because nothing that large ever prints.
The usual workaround is a threshold per coin. That works and nobody does it, because maintaining twenty numbers by hand is a chore that loses to inertia within a fortnight.
What BTC denomination fixes
Express every trade in bitcoin terms — convert the notional through the current rate — and one number starts behaving consistently. “Five BTC” describes a trade of roughly the same economic weight whether it printed on SOL/USDT, INJ/USDT or ETH/BTC.
Two practical benefits follow. First, one rule covers a whole watchlist without per-coin tuning. Second, and less obviously, the number stays meaningful over time: as the market repriced, five BTC has remained a recognisable size in a way that “$50,000” has not.
To be clear about what this is not: it is a unit of account, not a view on bitcoin. Nothing about measuring in BTC assumes BTC goes up, down or sideways — it is the same reason a shipping company measures in containers rather than in the value of the goods inside.
Quote groups: one ladder is not enough
There is a wrinkle. Markets quoted in different assets have genuinely different size distributions, and flattening them into one scale hurts.
A trade of 0.5 BTC is small on a USD-quoted book and substantial on a BTC-quoted one, because the participants are different — BTC-quoted books are used mostly by people already inside the asset. So the sane design is one ladder per quote group — USD-style quotes, BTC, ETH — with the same rule applying a different scale depending on which group the market belongs to.
In Pharos the ladders come from the server rather than being compiled into the app, which means they can be re-derived as markets change without anyone installing an update.
Build the ladder from percentiles, not round numbers
The last piece is where the steps come from. Round numbers — 1, 5, 10, 50 — feel natural and distribute badly: half of them land in a region where nothing ever fires and the rest are bunched where everything does.
The better method is to take a real sample of trades and cut the ladder at percentiles of the observed distribution, so each step up meaningfully reduces the hit rate. The user still sees a simple slider; what changed is that every position on it corresponds to a distinct real-world frequency instead of a distinct round number.
This is what makes a frequency estimate possible at all — and a frequency estimate is what turns threshold setting from guesswork into a decision, as covered in setting an alert you won’t mute.
What still needs per-coin attention
BTC denomination solves the units problem, not the liquidity problem. A pair with a very thin book can produce a large percentage move on a trade well below any sensible global threshold. If you follow small-caps specifically, they still deserve their own rule with its own scale — the point is that everything else no longer does.
Common questions
Why measure crypto trade size in BTC instead of dollars?
Because one BTC-denominated number behaves consistently across pairs. Dollar figures mean something different on every market, so a threshold that works on a major is deaf on an altcoin and vice versa, forcing a separate threshold per coin.
Does the threshold change when the bitcoin price changes?
The threshold stays the same number; what it converts to in dollars moves with the market. That is the intent — the unit tracks the market's own scale rather than an external currency, so a threshold set last year still describes a comparable trade today.
What is a quote group?
A grouping of markets by the asset they are priced in — USD-style quotes, BTC, ETH. Size distributions differ sharply between them, so each group gets its own ladder of threshold steps rather than sharing one scale.
What threshold should I start with?
Start from the frequency you want rather than the number. Pick a threshold that looks too high, check how often it would fire, and step down until the expected rate matches how often you are willing to be interrupted — for most people, a handful of times a day.
Pharos turns this into a push
Set one rule — say, buys above 5 BTC on your favourites — and the app tells you how often it will fire before you save it. Then it pushes you the moment it does.
See how Pharos worksWritten by the team building Pharos Trade. We make an alerting tool, not a trading service — nothing here is investment advice, and none of it predicts a price. Figures in examples are illustrative. Last reviewed 2026-08-23.