Fibonacci Retracement Calculator

Calculate Fibonacci retracement price levels between a swing high and a swing low, marking the 23.6%, 38.2%, 50%, 61.8%, and a custom ratio as potential support or resistance zones.

Quick Facts

Formula
Level = High − (High − Low) × ratio
Measured down from the swing high in an uptrend retracement, or up from the swing low in a downtrend retracement.
Key ratios
23.6%, 38.2%, 61.8%, 78.6%
Derived from ratios between numbers in the Fibonacci sequence; 50% is a widely-used add-on from Dow Theory, not a true Fibonacci ratio.

Your Results

Calculated
61.8% retracement
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Golden-ratio level, most watched by traders
50% retracement
-
Midpoint of the swing (Dow Theory, not Fibonacci)
38.2% retracement
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Shallow pullback level
Custom ratio level
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Price at your chosen ratio input

Ready

Enter the swing high, swing low, and direction, then press Calculate.

How the Fibonacci Retracement Calculator works

Fibonacci retracement is a technical-analysis tool used to mark potential support and resistance zones inside a price swing. You identify a swing high and a swing low on a chart, and the calculator measures a set of standard percentages back into that range. Those percentages — 23.6%, 38.2%, 50%, 61.8%, and 78.6% — are levels many traders watch for a pause or reversal during a pullback, though none of them is a guarantee.

The formula

For a retracement in an uptrend (price pulling back down after rallying from the low to the high), each level is measured down from the swing high:

Level = High − (High − Low) × ratio

For a retracement in a downtrend (price bouncing up after falling from the high to the low), each level is measured up from the swing low instead:

Level = Low + (High − Low) × ratio

The ratio is expressed as a decimal (61.8% = 0.618). At ratio 0% the level equals the starting point of the move (the high in an uptrend, the low in a downtrend); at ratio 100% it equals the opposite end of the swing.

Where the ratios come from

The Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89…) produces several ratios that converge as the sequence grows: dividing a number by the one immediately after it approaches 0.618 (the golden ratio); dividing by the one two places later approaches 0.382; and dividing by the one three places later approaches 0.236. 78.6% is the square root of 0.618. The 50% level is not a Fibonacci ratio at all — it comes from Dow Theory's observation that markets often retrace about half of a prior move — but charting platforms include it alongside the true Fibonacci ratios because traders watch it in practice.

Worked example

Take a stock that rallied from a swing low of $100 to a swing high of $150, a range of $50. In an uptrend retracement, the 61.8% level is $150 − ($50 × 0.618) = $119.10, the 50% level is $150 − $25 = $125.00, and the 38.2% level is $150 − ($50 × 0.382) = $130.90. A trader watching this pullback might treat $119–$131 as a zone of interest where buying pressure has previously reappeared, rather than a single precise line.

Using the levels responsibly

  • They are zones, not triggers. Price frequently pierces a level briefly before reversing, or ignores it entirely and keeps trending.
  • Combine with other signals. Volume, moving averages, prior support/resistance, and trend strength are commonly used alongside retracement levels rather than in isolation.
  • The swing points you choose matter. A different, equally defensible swing high or low produces a different set of levels — there is no single "correct" swing on most charts.
  • This is not investment advice. This calculator performs the retracement arithmetic only; it does not predict price movement or recommend any trade.

Frequently Asked Questions

How are Fibonacci retracement levels calculated?
Each level is a price between a swing high and a swing low. For a retracement in an uptrend, Level = High − (High − Low) × ratio, measured down from the high. For a retracement in a downtrend, Level = Low + (High − Low) × ratio, measured up from the low. The ratio is one of the standard Fibonacci retracement percentages: 23.6%, 38.2%, 50%, 61.8%, or 78.6%.
Where do the 23.6%, 38.2%, and 61.8% ratios come from?
They come from the Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89…). Dividing a number by the one two places later approaches 0.236, dividing by the one immediately after approaches 0.618 (the golden ratio), and dividing by the one three places later approaches 0.382. Traders apply these ratios to a price range to mark potential support and resistance zones.
Is 50% a true Fibonacci ratio?
No. The 50% level is not derived from the Fibonacci sequence — it comes from Dow Theory, which observed that markets often retrace about half of a prior move. Charting platforms and this calculator include it alongside the true Fibonacci ratios because traders watch it in practice, not because it has a mathematical Fibonacci origin.
Do Fibonacci retracement levels guarantee price will reverse there?
No. Retracement levels mark zones where price has historically tended to pause or reverse, based on the ratio and your chosen swing high and low — they are not a guarantee. Price can pass straight through a level, overshoot it, or reverse somewhere else entirely. This tool performs the arithmetic only; it is not investment advice, and trading decisions should weigh other analysis and your own risk tolerance.

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