Arithmetic and Geometric Sequence Calculator

Calculate an arithmetic or geometric nth term and finite sum, with a bounded list of terms and explicit indexing.

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How this works

The tool runs in this browser. Your file or text is not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

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Calculate sequence controls

Showing an example. Edit to see your own.

Arithmetic only.

Geometric only.

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How to use Arithmetic and Geometric Sequence Calculator

  1. Choose arithmetic or geometric and enter the first term.
  2. Enter the common difference or ratio and the positive term count.
  3. Review the nth term, finite sum and term list.

Example: Arithmetic and Geometric Sequence Calculator

Arithmetic and Geometric Sequence Calculator: Term 10 of the arithmetic sequence is 21, and the sum of the first 10 terms is 120.

You add
Sequence type: arithmetic First term (a1): 3 Common difference (d): 2 Common ratio (r): 2 Number of terms (n): 10
You get
Term 10 of the arithmetic sequence is 21, and the sum of the first 10 terms is 120. a1 = 3, d = 2, n = 10 a10 = 21 S10 = 120 Sequence type | arithmetic First term (a1) | 3 Common difference (d) | 2

Options

First term
The starting value is term 1. Arithmetic mode adds the common difference; geometric mode multiplies by the common ratio.
Term count
The list and sum include exactly the entered count. This is a finite sequence calculation, including when the ratio is zero or negative.

Supported inputs and limits

Up to 1,000 terms with bounded finite decimal settings. The first term is term 1. A geometric result is a finite sum, not an assertion that an infinite series converges. Results are refused when the configured numerical bounds are exceeded.

Where your input is processed

This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

Check the index used in the original problem

A formula that starts at index zero can describe the same values with different labels. This page uses one-based labels throughout. It does not infer a pattern from observations or claim convergence of an infinite geometric series.

Questions about Arithmetic and Geometric Sequence Calculator

Is the first term numbered zero or one?

One. The nth-term result uses the entered first term as a1.

Can a geometric ratio be zero or negative?

Supported finite calculations handle those values explicitly. A negative ratio alternates signs; zero makes terms after the first zero.

Does the tool find a pattern from a list?

No. You supply the arithmetic difference or geometric ratio.

Project manager: Tony Hines · Content updated 4 October 2026 · Report a problem