Open interest (OI) is the total size of all perpetual futures positions that are currently open on a market, counted once per contract. Every open long is matched by an open short, so open interest measures how much leverage is deployed in a market, not which way it leans.
A trade only changes open interest when it creates or destroys a position. If a new buyer meets a new seller, both open a position and OI rises by that size. If a long closes by selling to a short who is closing, both positions disappear and OI falls. If a long sells to a new buyer, the position changes hands and OI is unchanged. Volume counts all three; open interest only moves in the first two.
Exchanges report OI in contracts or in the base asset; Proliquid converts it to USD at the mark price so venues and markets can be compared. Because every long has a short on the other side, total long value and total short value are always equal. A market with $2.8B of BTC open interest has $1.4B of longs against $1.4B of shorts by construction.
Reading open interest with price
The signal is in the combination. Price rising with rising OI means new longs are being opened and the move is being funded by fresh leverage. Price rising with falling OI means shorts are closing, a squeeze that can end once they are done. Price falling with rising OI is new shorts; falling with falling OI is longs being closed or liquidated.
Sharp drops in open interest during a move usually mark liquidation cascades, and the market often stabilizes once they finish. Sharp rises without much price change mean both sides are adding leverage into a range, which tends to resolve violently. Compare OI with the funding rate to see which side is paying for the leverage, and with the liquidation map to see where it would be forced out.
Example: a squeeze versus a fresh trend
WORKED EXAMPLE
Two days on the same market, both up 4%. The tape looks similar; the open interest does not.
Day one price
$2,450 to $2,548 (+4%)
Day one OI
$3.1B to $2.6B (-16%)
Reading
Shorts closing; the move was covering, not new demand
Day two price
$2,548 to $2,650 (+4%)
Day two OI
$2.6B to $3.0B (+15%)
Reading
New longs opened; leverage is now on the long side
After day one the market had less leverage than before and little fuel left for a squeeze. After day two, a pullback would find $400M of fresh longs sitting close to their entry, with liquidation prices not far below.
DATA IN TERMINAL
Watch it live beside your chart.
The Proliquid screener ranks every market by open interest change, funding, volume, and volatility across all connected exchanges.
Open interest and funding beside 5- and 15-minute activity
What is the difference between open interest and volume?
Volume is how much traded during a period; it resets every day. Open interest is how much is still open right now; it only changes when positions are created or closed. High volume with flat OI means positions are changing hands rather than being built.
Does high open interest mean traders are long?
No. Longs and shorts always match, so OI says how much leverage is in the market, not which way. Use the funding rate for the lean: positive funding means the long side is paying, negative means the short side is.
Why does open interest differ between exchanges?
Each venue only counts its own contracts. Binance and Bybit typically carry the largest BTC open interest; Hyperliquid's is smaller but fully public, which is why its liquidation levels can be mapped position by position.
How does open interest relate to liquidations?
Open interest is the pool that liquidations drain from. When price hits a cluster of liquidation prices, those positions are force-closed and OI drops by their size. Large OI near the current price means a small move can force a lot of closing.