The perp premium is the gap between a perpetual future's price and the spot price of the same coin on the same exchange, calculated as (perp mid − spot mid) ÷ spot mid. A positive figure is a premium and a negative one is a discount. The table on this page shows it for every exchange where ArbTide collects both spot and perpetual prices. For the mechanism behind it, read what is the premium index.
How it works
- Measure the gap. For each exchange, take the mid price (halfway between best bid and best ask) of the spot market and of the perpetual.
- Compare with funding. Funding formulas are built on the premium, so a persistent premium usually comes with positive funding and a discount with negative funding. See what is a funding rate.
- Read the positioning. A large premium means traders are paying up for leveraged longs; a deep discount means shorts are crowded or hedgers are selling perps.
- Act on it, or not. Traders use a rich premium as an entry for cash and carry (buy spot, short the perp) and a deep discount for reverse cash and carry. Others use it only as a sentiment gauge.
Reading the scanner
- Exchange: the venue. Both markets are on the same exchange, so the figure is not affected by price differences between exchanges.
- Spot mid: the midpoint of the spot market's best bid and ask.
- Perp mid: the midpoint of the perpetual's best bid and ask.
- Premium: (perp mid − spot mid) ÷ spot mid. Positive values are a premium; negative values a discount.
- Funding rate and APR: the perp's current funding rate per interval, and that rate annualized (rate ÷ interval hours × 8,760).
To judge a row, check whether premium and funding agree. For example, a 0.3% premium with strongly positive funding points to crowded longs. A premium with neutral or negative funding may be a brief move that funding has not caught up with yet, or a sign the exchange's index uses different spot prices. Compare the same coin across exchanges: if one venue's premium sits far from the others, its traders are positioned differently, which can also show up as a funding spread. Watch how the premium changes over time too. In the language of dated futures, a persistent premium resembles contango and a discount resembles backwardation.
Costs and risks the scanner does not include
The premium is a reading, not a trade, so it carries no fees of its own. Turning it into a trade adds costs:
- Bid-ask spread: mid prices ignore the cost of crossing the book. A real entry pays the ask and receives the bid. The cash and carry scanner shows this as basis.
- Taker fees on both legs, at entry and exit. See maker vs taker fees.
- Mean reversion timing: a premium can widen further before it closes, and a crowded market can stay crowded.
- Funding changes: the rate resets each interval, and the premium can collapse after a large liquidation.
- Borrowing: acting on a discount usually needs a spot short, which costs borrow interest.
- Liquidation on the perp leg during sharp moves. See what is liquidation.
Read basis in crypto for how premium and basis relate, and the methodology for data details.
When it works best
The premium is most informative at extremes. Readings far from zero, lasting for more than a few funding intervals and appearing on several exchanges at once, point to crowded positioning that funding will keep charging for. Those are the conditions where basis entries have the most room. Small premiums near zero are normal and mostly reflect the bid-ask spread and short-term noise. Check live funding rates to see how the premium feeds through to each coin.