1. Calculation and units
Assume a reference price of 100 USDT and a comparison price of KRW 143,000. If USD 1 = KRW 1,400 and USDT 1 = USD 1.01, USDT 1 is KRW 1,414. The reference becomes KRW 141,400. The premium is (143,000 / 141,400 − 1) × 100, about 1.13%. These are illustrative assumptions, not current quotes.
2. Keep the FX direction explicit
krwPerUsd is KRW for one USD; usdPerUsdt is USD for one USDT. usdtPerUsd is its reciprocal. Multiply krwPerUsd by usdPerUsdt to obtain krwPerUsdt. Swapping exchanges changes the denominator, so the result is not simply the same percentage with the opposite sign.
3. Timestamps and missing values
FX is observed independently every 15 minutes. Where the source supplies no publication timestamp, the time records our observation. FX older than two hours is excluded from cross-currency comparisons; same-currency pairs remain comparable without FX. Stale quotes, large timestamp differences and provider failures can leave empty values. An empty value alone does not establish a delisting.
4. What the average does and does not mean
The displayed average is an unweighted mean over assets comparable for the selected pair. It is not the row count or a volume-weighted return. Last-price differences exclude order-book depth, fees, withdrawal restrictions, transfer time, conversion costs and taxes. They do not guarantee an achievable trading profit.
Sources and methodology
CoinMadang — Sources and methodology · Coinbase Exchange Rates API