What RVOL actually measures

Relative volume — RVOL — is the ratio of today's traded volume to an average day's volume over a recent window. Expressed as a multiplier: 1× is a normal day, 5× is heavy, 20× is extreme.

It's the most important number on a small-cap scanner, and almost everyone computes it wrong. This guide walks through the definition, the common mistake, and the version BullAlert's scanner actually uses. Nothing here is financial advice — always do your own DD before making any investment decision.

The naive formula (and why it's broken)

The version you'll find in most free scanners:

RVOL = today_volume / avg_daily_volume_20d

This is fine if you check it at 4:00 PM, after the session closes. It's useless at 9:45 AM, because you're dividing a partial day by a full day. A stock trading at 1.2× by 9:45 could be either "having a quiet morning" or "absolutely exploding" — the ratio can't tell you.

The fix: time-adjusted RVOL

The correct formula normalizes today's volume by the fraction of the average day that has already happened:

RVOL = today_volume / (avg_daily_volume_20d × expected_fraction_so_far)

The "expected fraction" has to account for the intraday volume curve — the well-known U-shape where volume spikes at the open and close and sags mid-session. At 9:45 AM, ~15% of the day's volume has usually printed. At noon, ~45%. At 3:55 PM, ~95%. BullAlert's scanner uses a 5-minute-resolution curve to compute this with precision.

With this fix, a stock trading at 2× at 9:45 AM means "already traded twice what it normally does by this point" — which is meaningful. Same stock at 2× at 3:00 PM means something completely different.

Why it matters for small caps

On large caps, RVOL is a nice-to-have. On small caps, it's the single most informative number you can look at. Here's why.

Small caps have tiny floats and thin average volume — often under 1M shares a day. When something catalytic happens (news, short squeeze, reverse split, whatever), volume expands 10–50× in hours. That volume expansion is the signal. Without it, price moves on small caps are just noise from a few retail orders.

Put another way: a small cap can go up 30% on 50k shares of volume and it means nothing. The same stock up 5% on 10 million shares means institutions are building a position. Which of those would you rather study?

RVOL buckets, not multipliers

BullAlert never displays the raw RVOL number to users. Instead we bucket it into four labels:

NORMAL — RVOL < 2×. Boring tape. Ignore.
ELEVATED — 2× to 5×. Something is happening. Watchlist material.
HIGH — 5× to 10×. Structural move. Study the chart.
EXTREME — 10×+. Rare and usually news-driven. The tape is yelling.

The bucketing is intentional. Raw multipliers create false precision — a "7.3× RVOL" stock isn't meaningfully different from a "6.8×" one. What matters is the regime: is volume structurally high, or isn't it? The buckets enforce that thinking.

Three RVOL traps to avoid

1. RVOL without price action

Volume without direction is just churn. A stock trading 10× normal volume but stuck in a flat range is distribution or indecision — usually both. Always pair RVOL with a clean price structure: uptrend, VWAP reclaim, opening range break, or bull flag.

2. RVOL on illiquid names

Very small floats (under 5M shares) can show 20× RVOL on an absolute volume that's still too thin to trade safely. Your order becomes the order flow. Always check absolute volume alongside RVOL — we want at least 100k shares traded in regular hours (50k in extended).

3. Extended-hours RVOL

Pre-market and after-hours RVOL can't use the same denominator as regular hours, because those sessions are naturally low-volume. BullAlert uses a separate expected-volume curve for extended hours: pre-market ≈ 10% of daily average, after-hours ≈ 5%. A "2× pre-market RVOL" stock isn't 2× of its full day — it's 2× of what pre-market usually delivers.

How Edgar uses RVOL

Edgar's paper-trading bots use RVOL buckets as a hard gate: no HIGH bucket, no trade. The regular-hours bot also requires ELEVATED (2×+) minimum; the after-hours bot is stricter and requires HIGH (5×+) because AH needs more conviction to sustain. Every Edgar diary entry shows the RVOL bucket at catch, so you can study how RVOL regime interacts with pattern outcomes.

RVOL Explained: The Only Volume Metric That Matters