Traders hunting for where a pullback might end reach for ratios found in sunflower spirals. After a stock surges from $100 to $200, Fibonacci retracement levels mark the prices where buyers historically step back in: 23.6, 38.2, 50, 61.8, and 78.6 percent of the way back down the swing. The 61.8 percent level -- the golden ratio's complement -- gets watched most closely, and because thousands of traders watch it, it often works as a self-fulfilling prophecy.

This calculator draws the map from your swing points. Enter the swing high and the swing low -- 200 and 100 in the example -- and it computes each retracement level as a price: the 38.2 percent retracement of that swing sits at $161.80, the 61.8 percent at $138.20. Day traders and swing traders place limit orders, stop losses, and profit targets around these lines, especially when they cluster with round numbers or moving averages.

Treat the levels as zones of interest, not force fields. Prices slice through Fibonacci lines constantly, particularly on news-driven moves, and no ratio repeals supply and demand. The professional use is confluence: a 61.8 percent retracement that also touches a rising 50-day average and a prior breakout point is a far stronger candidate than any single line alone. Map the levels, then demand confirmation before committing capital.

With the pre-filled defaults — Swing High $200, Swing Low $100 — the Fibonacci Retracement Calculator returns 0% Level $100.00, 23.6% Level $123.60, 38.2% Level $138.20, 50.0% Level $150.00, 61.8% Level $161.80, 78.6% Level $178.60, 100% Level $200.00. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.