# Open interest

Also written OI.

*https://cryptomarkets.tools/glossary/open-interest · next to Crypto Trading Terminals*

**Definition:** The number of derivative contracts open at a point in time — entered into and not yet closed, expired or settled. It counts positions outstanding rather than turnover, so a trade between two existing holders moves none of it while volume still rises. Every long is matched by a short, so there is one market-wide total and not two. Each venue reports it in units of its own choosing.

It is the second number every derivatives screener puts next to price, and the one most often read
as though it were a measurement of conviction. It is a count of contracts, in units the venue
chose, aggregated by a vendor who made a decision you cannot see from the chart.

## How it works

The regulator's definition is the clean one. The CFTC's explanatory notes for the Commitments of
Traders report define open interest as the total of all futures and option contracts entered into
and not yet offset by a transaction, by delivery, by exercise or otherwise, and state that the
aggregate of all long open interest equals the aggregate of all short open interest. Both halves
matter. It is a stock, not a flow — a level that persists until somebody closes a position — and
because every contract has two sides, a market-wide total is one number counted once, not the sum
of the longs and the shorts.

That is where the usual confusion with volume starts. Consider the four combinations of a single
trade. Both sides opening — open interest rises by one contract. Both sides closing — it falls by
one. One opening and one closing, in either direction — it does not move at all, because the
position changed hands rather than being created or destroyed. Volume records a trade in all four
cases. A day of frantic turnover between existing holders leaves open interest flat, and a quiet
day in which a few large positions are built moves it a long way.

**The units are not standard, and they are not always stated.** Binance's USDⓈ-M futures endpoint
for open-interest statistics returns `sumOpenInterest` and `sumOpenInterestValue` with no unit
annotation on either field. The endpoint of the same name on its COIN-M futures product annotates
both: `sumOpenInterest` is marked "unit: cont", meaning contracts, and `sumOpenInterestValue` is
marked "unit: base asset", meaning bitcoin on a BTCUSD contract. Two products at one venue, two
identically named fields, and three different quantities between them — a count of contracts, a
quantity of the base asset, and a notional in the quote currency.

This follows from how the contracts are built rather than from a documentation lapse. A
coin-margined contract is denominated in dollars and collateralised and settled in the coin, which
is why OKX computes the position value of a crypto-margined contract by dividing by the mark price
where a USDT-margined one multiplies by it. A count of contracts is only convertible to a notional
with the contract multiplier, and only convertible to a coin quantity with a price — and the price
used is the vendor's choice as well.

## What an aggregate is actually summing

"Total BTC open interest" is therefore a sum over instruments that do not share a unit. To add a
coin-margined contract to a USDT-margined one, a vendor has to convert at least one of them at some
price at some moment, and the result is a series that moves when the price moves even if not one
contract was opened. A dollar-denominated open-interest chart and a coin-denominated chart of the
same market can point in opposite directions on the same day, and neither of them is lying.

The vendors here differ in whether they normalise and in whether they say so. [Coinglass's
API](https://cryptomarkets.tools/tools/coinglass) publishes open interest as OHLC candles per pair and aggregated across
exchanges, with stablecoin-margined and coin-margined kept separate.
[Coinalyze](https://cryptomarkets.tools/tools/coinalyze) lists by contract rather than by coin, so quarterly and bi-quarterly
expiries and the coin-margined and stablecoin-margined pairs appear as their own rows instead of
being folded into one aggregate — and its per-coin aggregated charts carry the vendor's own notice
that they are not real-time, which the chart itself does not show. [Velo](https://cryptomarkets.tools/tools/velo) makes the
refusal to merge the product: its figures are broken down by the venue they came from, so "open
interest went up" becomes "open interest went up on Bybit while Binance was flat". Its catalogue,
counted from unauthenticated endpoints, holds 717 Binance USDT-margined futures products against
two coin-margined ones each on Binance, Bybit, OKX and Deribit — which is the shape of the problem
in one line, because the two coin-margined rows are not a rounding error in dollar terms.

## Why it matters here

Thirty-three of the ninety-two cards in this catalogue mention open interest: fourteen market-data
APIs, nine charting platforms, five on-chain analytics products, four
[terminals](https://cryptomarkets.tools/categories/trading-terminals) and one bot framework. It is one of the most widely
claimed fields here, and a claim to carry it says almost nothing about what arrives.

Coverage is thinner than the headline in a way that is visible when a vendor publishes a matrix.
[Amberdata](https://cryptomarkets.tools/tools/amberdata) documents a start date per dataset per venue, and on that matrix open
interest exists on 21 rows against funding rates on 16 of 20 futures venues, liquidations on 10 and
long/short ratio on 4. The product carries open interest; a particular venue on a particular date
may not.

So three questions before a number is used as a number rather than as a shape.

**In what unit, and converted at what price.** If the vendor cannot answer, the series is only
comparable with itself, and only while its denominator is stable.

**Which contracts are inside the aggregate.** Perpetuals only, or dated futures too; coin-margined
folded in or kept out; which venues, and whether delisted ones are still in the archive.

**At what moment it was sampled.** Open interest is a level, so a series of it is a series of
snapshots, and the snapshot interval is a property of the feed rather than of the market.

The reading everybody quotes — rising open interest with a rising price as new longs, rising open
interest with a falling price as new shorts — is a convention, not a measurement. No exchange
document assigns a direction to the count, and the count cannot distinguish a new position from a
hedge against one. It is a reasonable prior and it belongs in the same sentence as its caveat. The
other half of the perpetuals pair, [funding rate](https://cryptomarkets.tools/glossary/funding-rate), has the same problem in
a different form: a number whose interval the venue chose.

## Where you will meet this

- [Velo](https://cryptomarkets.tools/tools/velo.md)
- [CoinGlass API](https://cryptomarkets.tools/tools/coinglass.md)
- [Coinalyze](https://cryptomarkets.tools/tools/coinalyze.md)
- [Amberdata Market Data API](https://cryptomarkets.tools/tools/amberdata.md)
- [CoinAnk](https://cryptomarkets.tools/tools/coinank.md)
- [Laevitas](https://cryptomarkets.tools/tools/laevitas-platform.md)
- [Exocharts](https://cryptomarkets.tools/tools/exocharts.md)
- [3Commas](https://cryptomarkets.tools/tools/3commas.md)
- [AGGR](https://cryptomarkets.tools/tools/aggr.md)
- [Allium](https://cryptomarkets.tools/tools/allium.md)
- [Altrady](https://cryptomarkets.tools/tools/altrady.md)
- [Arkham](https://cryptomarkets.tools/tools/arkham.md)

## FAQ

### What is the difference between open interest and volume?

Volume counts trades over a period and resets. Open interest counts contracts still open at an instant and carries forward. A single trade can raise open interest by one contract, lower it by one, or leave it unchanged depending on whether each side was opening or closing — and it adds to volume in all three cases.

### Why do two vendors report different open interest for the same coin?

Usually units and scope rather than a data error. One may be summing contracts, another base-asset quantity, another a USD notional converted at a price that moves; and venue lists differ, with coin-margined and stablecoin-margined contracts sometimes folded into one figure and sometimes kept apart. Compare the unit and the venue list before concluding either number is wrong.

### Does rising open interest mean new money is entering?

That is a reading, not a measurement. Open interest tells you contracts were opened, not who opened them or why, and no exchange document assigns it a direction. The common convention pairs rising open interest with a rising price as new longs and with a falling price as new shorts; it is an interpretation layered on a count, and it should be labelled as one.

### Can I compare open interest denominated in coins with open interest in dollars?

Not directly. A dollar-denominated series moves when the price moves even if no contract was opened or closed, and a coin-denominated one does not. The two charts of the same market can point in opposite directions on the same day, and neither is wrong.

## Sources

1. [Commitments of Traders — Explanatory Notes](https://www.cftc.gov/MarketReports/CommitmentsofTraders/ExplanatoryNotes/index.htm) — U.S. Commodity Futures Trading Commission, read 2026-09-21
2. [Open Interest Statistics (USDⓈ-M Futures)](https://developers.binance.com/docs/derivatives/usds-margined-futures/market-data/rest-api/Open-Interest-Statistics) — Binance, read 2026-09-21
3. [Open Interest Statistics (COIN-M Futures)](https://developers.binance.com/docs/derivatives/coin-margined-futures/market-data/rest-api/Open-Interest-Statistics) — Binance, read 2026-09-21
4. [Perpetual futures funding fee mechanism](https://www.okx.com/en-us/help/iv-introduction-to-perpetual-swap-funding-fee) — OKX, 2026-08-27

*Last updated 2026-09-21. A reference page, corrected in place — not a dated post.*