Math & Geometry
Sequence Sum Calculator
Calculate the sum of an arithmetic sequence from its first term, last term, and number of terms.
- Free to use
- Runs in your browser
- Level A · Standard formula
- Last reviewed 2026-08-16
Calculator guide
How to use the Sequence Sum Calculator
Calculate the sum of an arithmetic sequence from its first term, last term, and number of terms. Enter the requested values and select Calculate. The result and supporting values are produced locally in your browser.
Formula
Worked example
The arithmetic sequence from 3 to 39 with 10 terms has a sum of 210.
What to keep in mind
- This formula applies to arithmetic sequences when the first term, last term, and term count are known.
Methodology
This calculator uses deterministic arithmetic and performs the calculation locally in your browser. Verify assumptions, units, and source values for your specific use case.
Review standard: Level A · Standard formula. How calculator reviews work.
Frequently asked questions
What does this calculator calculate?
Calculate the sum of an arithmetic sequence from its first term, last term, and number of terms.
How is the result calculated?
Sₙ = n(a₁ + aₙ) ÷ 2.
Can I use the result for an important decision?
Use the result as a calculation aid and verify the inputs, assumptions, and applicable professional or regulatory requirements before relying on it for an important decision.
Does CalculateMeasure store the values I enter?
The calculator performs its arithmetic in your browser. The calculator itself does not need to send your entered values to a server to produce the result.