How this calculator works
Fibonacci retracement divides the distance between a recent swing low and swing high into fractions based on the Fibonacci sequence. Traders watch these levels as places where a pullback might stop and the previous trend resume. In an uptrend the levels are measured down from the high; in a downtrend they are measured up from the low. The levels shown here run from 0% (the end of the move) to 100% (its start), with the most watched at 38.2%, 50% and 61.8%. The 50% level is not a Fibonacci ratio at all, but it is included because it is widely used. Extensions project beyond the end of the move, giving possible targets if the trend continues: a 161.8% extension sits 61.8% of the swing beyond the high in an uptrend. Two cautions. First, the levels depend entirely on which swing you pick, so different traders get different numbers from the same chart. Second, the levels have no mechanical forecasting power; they work, when they work, because traders watch them and place orders around them. A retracement is a way to organise a chart, not a guarantee that a price will turn.
Formula
Range = high - low. In an uptrend, retracement level(r) = high - range x r, and extension level(r) = high + range x (r - 1). In a downtrend, retracement level(r) = low + range x r, and extension level(r) = low - range x (r - 1). The ratios are 0%, 23.6%, 38.2%, 50%, 61.8%, 78.6% and 100%, with extensions at 127.2%, 161.8%, 200% and 261.8%.
Worked example
A stock rises from $100 to $150, a range of $50. The 23.6% retracement is $150 - $50 x 0.236 = $138.20, the 38.2% level is $130.90, the 50% level is $125, and the 61.8% level is $119.10. The 78.6% level is $110.70. The 161.8% extension is $150 + $50 x 0.618 = $180.90, and the 261.8% extension is $230.90.
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Frequently asked questions
Which Fibonacci levels matter most?
The 38.2%, 50% and 61.8% levels attract the most attention, with 23.6% and 78.6% also watched. A pullback that holds above the 61.8% level is often read as a shallow retracement; a break below 100% suggests the trend has reversed.
Why is 76.4% sometimes used instead of 78.6%?
76.4% is 1 - 0.236, which some charting tools use as a complement to the 23.6% level. The more common ratio in Fibonacci analysis is 78.6%, which is the square root of 0.618. Charts differ on which one to show; the difference in price is small.
Do Fibonacci retracements predict prices?
No. They are a way of marking possible support and resistance. A level working out is evidence that other traders were watching it, not proof that the ratio itself has predictive power.
How do I choose the swing high and low?
Use a clear, dominant swing that stands out on the timeframe you trade. Most charting platforms offer an automatic Fib tool that anchors to the most recent substantial move, but the choice remains a judgement call.
What does a break below the 100% level mean?
In an uptrend, a fall below the original swing low means the entire move has been given back. That is usually treated as a change in trend rather than a retracement, and the Fibonacci structure no longer applies.