What is a Hammer Candlestick? Definition, Formula, and Example
A hammer candlestick is a single-bar bullish reversal pattern that forms at the bottom of a downtrend, characterized by a small real body near the top of its range and a lower shadow at least twice the body length, reflecting intraday rejection of lower prices by buyers.
What Is a Hammer Candlestick?
A hammer candlestick is a single-bar bullish reversal pattern with a small real body positioned near the upper end of its price range and a long lower shadow that extends at least twice the body length below it, with little to no upper shadow. The shape reflects a session where sellers drove price sharply lower intraday, but buyers absorbed that selling and pushed price back up to close near the session open — a direct signal that downward pressure is weakening and buyers are stepping in.
How It's Identified
Three criteria define a valid hammer:
1. Lower shadow ≥ 2× the body length
2. Upper shadow ≤ 10% of body length (negligible or absent)
3. Location: at the bottom of a sustained downtrend or at a recognized support level
Expressed mathematically:
- Body = |Close − Open|
- Lower shadow = min(Open, Close) − Low
- Upper shadow = High − max(Open, Close)
- Valid when: Lower shadow ≥ 2 × Body AND Upper shadow ≤ 0.1 × Body
Body color is secondary. A green hammer (close above open) is marginally more bullish than a red hammer (close below open), but both qualify. The inverted hammer shares the same logic with a long upper shadow instead — same reversal implication, requires stronger confirmation.
Worked Example
SPY on October 27, 2023, during the multi-week autumn sell-off:
- Open: $415.12 | Low: $410.62 | Close: $417.48 | High: $418.20
- Body = $417.48 − $415.12 = $2.36
- Lower shadow = $415.12 − $410.62 = $4.50 (1.91× body)
- Upper shadow = $418.20 − $417.48 = $0.72 (30% of body)
The lower shadow meets the 2× threshold; the upper shadow slightly exceeds the strict 10% rule but remains minor. Volume ran 85 million shares versus the 20-day average of 62 million — above-average volume confirms buyer absorption at the low. The formation appeared directly at a multi-month horizontal support zone. SPY rallied more than 5% over the following two weeks.
When Traders Use It
Hammers are most actionable when the following conditions stack:
- Three or more consecutive declining sessions precede the hammer
- Volume on the hammer candle exceeds the 20-day average — confirms selling pressure was absorbed, not just absent
- The pattern forms at a prior support level, Fibonacci retracement zone, or the session VWAP
- RSI is in oversold territory (below 30), adding independent confirmation
Entry mechanics: long on the next candle's open, or on a break above the hammer's high. Stop loss below the hammer's low — a close below the low invalidates the pattern entirely.
Limitations and Common Misconceptions
Confirmation is not optional. A hammer alone is not a trade signal; a bearish candle closing below the hammer body on the following session invalidates the setup. A hammer appearing mid-range — away from a known support level or technical inflection point — has meaningfully lower hit rates than one forming at confluence. Studies of candlestick patterns in isolation show modest statistical edge; the hammer works as a filter within a multi-factor framework, not as a standalone trigger.
Do not confuse a hammer with a spinning top, which has long shadows on both sides with a small body — that pattern signals indecision, not bullish reversal. Do not confuse with a doji (doji), which has a near-zero body size and does not require a dominant lower shadow.