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Geometric Sequence Calculator

n-th term and sum of a geometric sequence.

Compute the n-th term and the sum of the first n terms of a geometric sequence from its first term and common ratio.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

aₙ = a₁ · rn−1; Sₙ = a₁ · (rⁿ − 1) / (r − 1) for r ≠ 1.

In depth

Compute the n-th term and the sum of the first n terms of a geometric sequence from its first term and common ratio.