Fibonacci Calculator
Retracement and extension levels from any swing high and low, for uptrends and downtrends, with the arithmetic shown and an honest note on what the levels can and cannot tell you.
By Joey van Diest, founder and editorUpdated
Retracements
Pullback levels inside the move
Extensions
Target levels beyond the move
The formula
uptrend retracement = high − (high − low) × ratio
downtrend retracement = low + (high − low) × ratio
extensions use the same form with ratios above 1
It is one subtraction. In an uptrend you measure down from the high by a fraction of the range; in a downtrend you measure up from the low. With a swing from 1.0800 to 1.1200, the range is 0.0400, so the 61.8% retracement of the uptrend sits at 1.1200 − 0.0400 × 0.618 =1.09528, and the 38.2% at 1.10472. Extensions continue past the end of the move: the 161.8% extension of that same swing is 1.0800 + 0.0400 × 1.618 =1.14472.
What these levels are worth
Worth being straight about: there is no mechanism by which ratios derived from a number sequence should govern the price of anything, and the rigorous evidence that they predict reversals is thin. What is genuinely true is that a large number of traders draw the same levels off the same obvious swing, so orders cluster there and price often does react, for reasons that are social rather than mathematical. That makes them useful as places to watch, and misleading if treated as a reason on their own to take a trade.
The tool's real weakness is the anchor. Two traders can pick different swing points on the same chart and produce entirely different levels, and it is very easy to choose the pair that flatters a view you already hold. Pick the clearest recent impulse move, use it consistently, and require confirmation from something independent before acting. Then let therisk/reward calculatorjudge whether the distance from your entry to a retracement stop and an extension target is actually worth taking, and theposition size calculatorturn that stop into a size. The levels are the easy part; the sizing decides the outcome.
Frequently asked questions
- Where do the ratios come from?
- From the Fibonacci sequence. Dividing a term by the next gives roughly 0.618, skipping one gives 0.382, and 0.236 comes from skipping two; 1.618 is the inverse of 0.618. The 50% level is not a Fibonacci ratio at all, it is simply the midpoint, included by convention because traders watch it. 78.6% is the square root of 0.618. Knowing which levels are arithmetic convention rather than sequence-derived is worth more than treating all of them as mystical.
- Do Fibonacci levels actually predict reversals?
- There is no mechanism by which a ratio from a medieval number sequence should govern markets, and the honest evidence for predictive power is weak. What is real is that a great many traders draw the same levels from the same obvious swing, so those prices attract orders and can behave like support or resistance for entirely self-fulfilling reasons. Use them as candidate levels to watch, confirmed by something else, not as standalone signals.
- How do I pick the swing high and low?
- Use a swing that is obvious on the timeframe you trade, the kind a stranger would pick out of the same chart. If you have to hunt for the anchor points that make the levels fit your bias, you have stopped analysing and started rationalising. Ambiguity in choosing the swing is the single biggest weakness of the tool, so prefer the clearest recent impulse move and stay consistent.
- What is the difference between retracement and extension?
- Retracements sit inside the move and answer "how deep might the pullback go before the trend resumes". Extensions sit beyond the move and answer "if the trend does resume, where might it reach". Retracements are commonly used for entries, extensions for targets, which pairs naturally with a risk-to-reward calculation.
Method and limitations
Pure arithmetic on the two prices you enter, computed in your browser; nothing is fetched and nothing you type leaves the page. The 50% level is a conventional midpoint, not a Fibonacci ratio. These are reference levels derived from past prices, with no predictive guarantee, and the choice of swing points materially changes them. This is an information tool, not trading advice.
This tool runs entirely in your browser. Nothing you enter is sent to us or stored.
For general information and education only. This is not financial advice and not a recommendation to buy or sell anything. Trading and investing carry risk, including the risk of losing more than your initial outlay. Always verify figures against your broker or the original source before acting on them.
Spotted an error? Email[email protected]and it will be corrected. Maintained byJoey van Diest.