Arithmetic Sequence Calculator
List every term, find the Nth term, and compute the sum of an arithmetic sequence from its first term and common difference — runs 100% in your browser with no upload.
2, 5, 8, 11, 14
14
40
🔒 Calculated in your browser — nothing is uploaded.
What this arithmetic sequence calculator does
Enter the first term, the common difference, and how many terms you want, and this tool instantly lists the whole sequence, highlights the Nth (last) term, and adds everything up into a total. An arithmetic sequence is any list of numbers where each term is found by adding the same fixed amount — the common difference — to the one before it, such as 2, 5, 8, 11, 14. The difference can be positive, negative, or zero, and both the first term and the difference may be decimals, so the calculator works for whole numbers and fractions alike.
The formulas behind the results
The Nth term is computed directly with a₁ + (N − 1) × d, so you get the value of the last term without walking through every step. The sum uses the classic closed-form series formula N / 2 × (2 × a₁ + (N − 1) × d), which is far faster and more precise than adding the terms one by one. Everything recalculates live as you type, and each result has its own copy button. To keep the listing readable and responsive, the number of terms is limited to 1000.
Frequently asked questions
How is the Nth term different from the sum?
The Nth term is the value of a single term — the last one in your list — found with a₁ + (N − 1) × d. The sum adds every term together, from the first up to the Nth, using the series formula N / 2 × (2 × a₁ + (N − 1) × d).
Can the common difference be negative or a decimal?
Yes. A negative difference produces a decreasing sequence, a difference of zero repeats the first term, and decimals are fully supported for both the first term and the difference.
Is anything I enter uploaded to a server?
No. Every calculation runs entirely in your browser using JavaScript. The numbers you type are never sent, stored, or logged anywhere.