Fibonacci sequence calculator

Find Fₙ exactly with F₀ = 0, F₁ = 1 and Fₙ = Fₙ₋₁ + Fₙ₋₂.

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Index n (F₀ = 0)

Answer

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Find Fₙ exactly with F₀ = 0, F₁ = 1 and Fₙ = Fₙ₋₁ + Fₙ₋₂.

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Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

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Formula and assumptions

The index is a whole number from 0 to 1,000. Integer arithmetic is exact; the displayed sequence preview stops at index 50 to keep it readable.

Whole-number and finite-decimal arithmetic is exact within the stated input limits. Any requested rounding uses the selected setting. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-20

Using Fibonacci sequence calculator

Find Fₙ exactly with F₀ = 0, F₁ = 1 and Fₙ = Fₙ₋₁ + Fₙ₋₂.

The index is a whole number from 0 to 1,000. Integer arithmetic is exact; the displayed sequence preview stops at index 50 to keep it readable.

Next: Factorial calculator

A worked example

Example inputs: index n (f₀ = 0) = 10. Fibonacci number = 55.

Before you use the result

The index is a whole number from 0 to 1,000. Integer arithmetic is exact; the displayed sequence preview stops at index 50 to keep it readable. Whole-number and finite-decimal arithmetic is exact within the stated input limits. Any requested rounding uses the selected setting.

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