The hidden cost of a price tick on Upbit
On Upbit's won market a coin priced at 128 won moves in steps of 1 won. Each step is 0.78% of the price, more than fifteen times the exchange's fee. For anyone trading often, the tick can matter more than everything else.
How this was made: the code, the research runs and the first drafts of this text were produced by an AI assistant (Claude) working under the operator's direction; the operator made every decision and checked the numbers. All trading was on paper: real prices, no real money. Nothing here is investment advice.
What a tick is
Exchanges only accept prices on a fixed grid. On Upbit's won market the step depends on the price band: 1,000 won for coins above 1 million won, 1 won for coins between 100 and 5,000 won, 0.1 won between 10 and 100 won, and so on. Because the step is a fixed number of won within each band, its cost as a share of the price swings from 1% at the bottom of some bands to a few hundredths of a percent at the top.
What it cost us
- Our first paper trader in September 2026 used market orders on small coins. Its median round-trip cost was 0.46%, against signals worth +0.02% to +0.08% per trade before costs. The story.
- In October 2026 the coins priced between 100 and 1,000 won in our test (DOGE, XLM, ADA, ARB, LSK) had ticks worth 0.26% to 0.78% of their price; BTC, ETH, SOL and BCH had ticks below 0.05%.
- Across 31,407 backtests, charging one tick per trade cut the share of profitable 3-minute setups from 58% to 6%, and barely moved 4-hour results. Why short bars are hit hardest.
- Our 4-hour server test, which traded rarely and mostly large coins, filled on average 0.05% worse than the signal price.
The table has changed before
Upbit changes its tick table from time to time. In October 2024, sixteen coins priced between 100 and 1,000 won moved from 0.1-won to 1-won ticks, a tenfold rise in the cost of one step. On 31 July 2025 the table changed again and most steps above 5,000 won became coarser: a coin at 60,000 won went from 10-won to 50-won steps, and one at 1.5 million won from 500-won to 1,000-won steps. Today every coin between 100 and 1,000 won moves in 1-won steps. A strategy built before a change can find its costs multiplied overnight, so check the current table, and your coin's price, before you trade.
What to do about it
- Work out the tick as a share of your coin's price before you design a strategy for it. The tick size calculator does it for any price.
- Prefer slower strategies on coarse-tick coins: a 0.78% tick is small next to a 10% trend move and fatal next to a 0.3% scalp.
- Limit orders avoid paying the spread, but only when they fill; the trades they miss tend to be the good ones.
- When you backtest, charge at least one tick per trade, or use bid and ask prices instead of closes.