What is the put/call ratio and how is it calculated?
The formula is simple: put/call ratio = put volume ÷ call volume. Hypothetical: on one day, 420,000 puts and 600,000 calls trade in a group of options. The ratio is 420,000 ÷ 600,000 = 0.70. If puts rise to 660,000 the next day with calls unchanged, it is 1.10.
A ratio above 1 means more puts than calls traded; below 1, more calls than puts. It counts contracts, not dollars, and it does not know whether each contract was bought or sold, or whether the trade opened or closed a position. That last point is behind most misreadings. If calls and puts are new to you, see call vs put.
- Put/call ratio (PCR)
- Put volume divided by call volume, or put open interest divided by call open interest, for a market, an index or a single stock over a set period.
- Equity put/call ratio
- The ratio computed from options on individual stocks. Cboe publishes one daily for the options traded on its market.
- Index put/call ratio
- The ratio computed from options on stock indexes such as the S&P 500. It usually runs higher than the equity ratio because index puts are widely used for hedging.
Volume-based vs open-interest-based put/call ratio
The volume-based ratio uses the contracts traded in a session. It reacts fast and is noisy: one busy morning can swing it. It is the version most often quoted in market commentary.
The open-interest ratio divides put open interest by call open interest, the contracts still open after the close (see open interest). It moves slowly and describes positions built up over time rather than today’s activity. Because open interest is updated once a day, so is this ratio.
The two can disagree. Hypothetical: a stock’s calls show heavier volume than its puts today, a volume ratio of 0.60, while its put open interest, built over months by investors hedging their shares, is still larger than its call open interest, an open-interest ratio of 1.30. Neither is wrong; they measure different things. The drawing below shows open interest by strike for one expiration, puts on the left and calls on the right.
Equity, index and total put/call ratios: why they differ
Cboe publishes daily put/call ratios for the options traded on its market, including a total ratio, an index ratio, an equity ratio and one for exchange-traded products such as ETFs, plus ratios for single products such as SPX. Many market data sites republish them.
The index ratio usually sits higher than the equity ratio, and the reason is structural rather than a sign of extra fear. Fund managers and other holders of stock portfolios buy index puts, such as puts on the S&P 500 through SPX options, to insure their holdings. That steady hedging demand keeps index put volume high. In single stocks, call buying by individual traders is a bigger share of activity, which pulls the equity ratio lower.
That is why one version cannot be compared with another, or a level from one applied to the other. A reading that is normal for the index ratio could be unusual for the equity ratio. The total ratio blends all of them, so its mix shifts with whatever is busiest that day.
What is a good put/call ratio? Read it against its own average
There is no universal good or bearish number. Each version has its own typical range, and that range drifts over the years as products, participants and trading habits change; the growth of short-dated options is one example. A threshold quoted in an old article may not fit today’s market.
A sturdier approach is to compare the ratio with its own recent history: a moving average, such as 10 or 20 days, and how far today’s reading sits above or below it. Hypothetical: an equity ratio averaging 0.58 over 20 days jumps to 0.85. That is a large move relative to its own norm and worth noticing, whatever a textbook level says. A reading of 0.60 in the same series is unremarkable.
Many traders also smooth the daily ratio with a short moving average to cut the noise, then look for readings far outside its usual band. That is all the gauge at the top of this page is meant to show: low and high are relative to the series’ own average, not fixed numbers.
The contrarian reading: fear and complacency at extremes
The classic interpretation treats the ratio as a sentiment gauge and reads it the opposite way. When it spikes far above its average, traders are paying up for protection, which can happen near a washout low when fear peaks. When it sinks far below its average, call buying dominates, which can reflect complacency near a top. In both cases the idea is that the crowd is most one-sided just before a turn.
In the drawing below, the first spike in the ratio lines up with a price low that holds. The second spike looks just as large, but price keeps falling afterwards. Both happen in real markets, and you cannot tell them apart on the day. Extremes can persist, and a market in a real decline can keep producing high readings for weeks.
So treat an extreme reading as a reason to look more closely, not as an entry. If a trade follows, it still needs its own plan: a level on the chart, a stop and a size, as covered in risk management.
Why the put/call ratio often misleads
The ratio squeezes millions of trades with different motives into one number. The common reasons it gives a false read:
- Hedging, not betting. Much put volume comes from investors protecting stock they own. More hedging can mean nervous holders, but they are still holding.
- Bought or sold? The ratio counts contracts, not direction. Puts sold for income and calls sold against shares count the same as puts and calls bought.
- Single large trades. One institution rolling a big hedge or opening a spread can move a day’s ratio, especially on a single stock.
- Multi-leg trades. A put spread adds two puts; a collar adds a put and a call. The legs add volume without one clear view. Our options strategies overview shows how many trades combine both types.
- Short-dated and 0DTE options. A large share of index option volume is now in contracts that expire the same day and are traded in and out within hours (0DTE options). That activity can swing a volume-based ratio without saying much about how investors are positioned.
- Structural drift. Typical levels change over the years, so an old threshold can stop meaning anything.
Put/call ratio for a single stock
You can calculate the same ratio for one stock or ETF, from its options volume or open interest, and many options platforms display it. It is far noisier than the market-wide versions. Hypothetical: a stock usually trades about 20,000 calls and 12,000 puts a day, a ratio near 0.60. One day a single order buys 30,000 puts as a hedge before earnings, and the ratio jumps to about 2.1 on one trade.
Before reading anything into a single-stock spike, check what drove it: one block or many trades, which strikes and expirations, whether open interest rose the next day, and whether an event such as earnings is coming, when hedging demand and implied volatility usually rise. For where positions sit, look at open interest by strike; for the hedging flows behind them, see gamma exposure (GEX).
How to use the put/call ratio in practice
Used carefully, the ratio is one piece of context next to price, volume and volatility. It is not a timing tool and it does not replace a plan. A simple routine:
- Pick one version and stick with it: equity, index or total, volume or open interest, from one source.
- Smooth it with a short moving average and note its usual range over recent months.
- Flag readings far outside that range, and look at what drove them before drawing conclusions.
- Check price: a high reading near support after a sharp drop says something different from a high reading in a market still breaking down.
- Keep entries, stops and size on the chart of what you trade, and size every position so that being wrong is affordable.