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Summation Calculator

Sum a series written in sigma notation using the index letter n.

Sum a series in sigma notation

Sum: —
—
Use n as the index. Operators plus, minus, times, divide, power and brackets are supported.

How to use the Summation Calculator

  1. Type the term of the series using n as the index.
  2. Set the lower and upper limits of the summation.
  3. Read the total and the summary of the terms below.

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Frequently Asked Questions

Common questions about the free online summation calculator.

Type a term such as n squared, set the lower and upper index, and the sum of the series is calculated instantly.
Sigma notation is shorthand: the term is evaluated at every whole number index between the limits and the results are added.
The tool supports plus, minus, times, divide, power and brackets, so terms like n cubed over two work correctly.
Use the letter n as the index. The letters i and k are also accepted if you prefer that notation.
The sum of n from 1 to 100 is 5050, which is a useful way to confirm that the tool is working correctly.
No. Parsing the term and adding the values happen entirely in your browser, so nothing is uploaded.
Yes. It is completely free, with no account, no sign-up and no limit on the number of series you sum.
Sums are capped at a hundred thousand terms so the page stays fast and responsive on any device.

Last updated: October 10, 2026