The gold spread is the difference between the bid and ask price quoted on XAUUSD, and it is the first cost every gold trade pays. Because a standard lot is one hundred troy ounces, each cent of spread equals one dollar of cost, so a twenty five cent spread costs twenty five dollars per lot the instant the position opens.
Gold spreads are not constant. They are tightest during the London and New York overlap when liquidity is deepest, and they widen predictably at the daily platform rollover, through the thin Asian session and in the seconds around United States inflation, employment and Federal Reserve announcements, where a twenty cent spread becoming a two dollar spread is routine.
Total gold trading cost is spread plus commission plus overnight swap on positions held past rollover. Comparing brokers on advertised spread alone is misleading; the meaningful comparison is all-in cost per round turn measured on your own account during the hours you actually trade, which is also the figure that determines whether a short-target scalping approach is viable at all.