What is Relative Volume (RVOL)? Definition, Formula, and Example
Relative Volume (RVOL) is a ratio comparing a stock's current traded volume to its average volume over a lookback period, quantifying unusual activity as a multiple of normal.
Plain-English Definition
Relative Volume (RVOL) is the ratio of a stock's current trading volume to its typical volume at the same point in the session over a historical lookback period. It quantifies *how unusual* today's activity is. An RVOL of 1.0 means volume is exactly average; 5.0 means volume is five times normal. RVOL is the primary scanner filter for day traders hunting stocks "in play" — catalysts, news, earnings, or unidentified institutional flow show up as RVOL spikes before price has fully moved.
How It's Calculated
Two common formulations:
Cumulative RVOL (most widely used):
RVOL = Volume Today So Far / Average Volume at Same Time-of-Day over N Days
For example, at 11:00 AM ET, you compare today's cumulative volume through 11:00 to the average cumulative volume through 11:00 over the past 20 trading days. This corrects for intraday U-shape volume distribution (heavy at open and close, light mid-day).
Daily RVOL (simpler):
RVOL = Today's Volume / N-Day Average Daily Volume
Typically N = 20 or 50. The daily version is only meaningful after the close; intraday, it produces low readings early and high readings near the close regardless of true unusual activity.
Tapeboard's scanner uses cumulative RVOL with a 20-day lookback, the retail standard popularized by scanners like Trade Ideas and ThinkorSwim.
Worked Example
AMD has a 20-day average volume of 45 million shares. It's 10:30 AM ET. Historically, by 10:30 AM, AMD has traded an average of 14 million shares.
Today, AMD has already traded 42 million shares by 10:30 AM — earnings released last night beat estimates by 18%.
Cumulative RVOL = 42M / 14M = 3.0
The stock is trading at 3x its normal pace for this time of day. Compare to a naïve daily calculation: 42M / 45M = 0.93, which would incorrectly suggest *below-average* volume because the full day hasn't elapsed.
Another example: GME during the January 2021 short squeeze hit RVOL readings above 15.0 for five consecutive sessions — a historically extreme breadth of activity that preceded the vertical move.
When Traders Use RVOL
- Scanning for unusual activity — filter watchlists for RVOL > 2.0 to isolate stocks with news, rotation, or institutional flow
- Gap-and-go setups — high RVOL on a morning gap confirms genuine institutional interest versus a thin premarket fade
- Breakout confirmation — price breaking resistance on RVOL > 3.0 has substantially higher follow-through than the same break on RVOL of 0.8
- Avoiding chop — low RVOL (< 0.7) stocks tend to mean-revert within their opening range; high-RVOL names trend
- Earnings and catalyst trades — RVOL is the cleanest real-time proxy for "market is paying attention"
Scanner setups commonly require minimum price ($2 or $5), minimum daily volume (1M shares), and RVOL threshold (2.0-5.0) as a baseline "in play" universe.
Limitations and Common Misconceptions
RVOL is a coincident indicator, not a leading one. By the time RVOL spikes to 5.0, the move is often already underway. It identifies *where* to look, not *when* to enter.
Opening RVOL is distorted. Low-float stocks and premarket movers produce eye-popping RVOL readings in the first five minutes that normalize by 10:00 AM. Wait for stabilization before acting.
RVOL ignores direction. A stock can have RVOL of 10.0 in a vertical rally or a vertical collapse — the metric is agnostic. Always pair with price action and VWAP.
Lookback window matters. Recent earnings or news in the lookback window inflate the denominator, suppressing current RVOL readings. Seasonal stocks (HD in spring, retail at Black Friday) also distort comparisons.
RVOL ≠ dollar volume. A $2 stock with 100M shares has huge RVOL but tiny notional turnover. Institutional flow is better tracked with dollar volume or open interest on options.