Arithmetic Sequence Calculator
Find the nth term, common difference and sum of an arithmetic sequence or series free in your browser with this easy arithmetic sequence calculator.
Enter Values
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How to use this calculator
- Enter the first term, common difference and term number.
- Press Calculate.
How it works
Each term adds a fixed difference. The nth term = first + (n − 1) × difference; the sum = n ÷ 2 × (first + last).
Worked example
2, 5, 8… (n=5). 5th term 14, sum 40.
Common mistakes
- Confusing the common difference with the first term.
- Mixing up the nth-term formula with the sum formula.
Frequently asked questions
What is an arithmetic sequence?
A sequence with a constant difference between terms. The nth term = a + (n − 1) × d, where a is the first term and d the common difference.
How do I find the difference?
Subtract any term from the one after it; in 3, 7, 11, 15 the common difference is 4.
What is the common difference?
The fixed amount added to get from one term to the next. In 2, 5, 8… the common difference is 3.
Related tools
- Geometric Sequence Calculator
- Fibonacci Calculator
- Arithmetic Series Sum Calculator
- Geometric Series Sum Calculator
- Average (Mean) Calculator
- GCD & LCM Calculator
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Cite this tool
Zerdly. (2026). Arithmetic Sequence Calculator. Retrieved from https://www.zerdly.com/tools/arithmetic-sequence-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.