Arithmetic Sequence Calculator
Nth term and sum of an arithmetic sequence.
How it works
The nth term is a1 + (n − 1) × d. The sum is n × (first + last) ÷ 2. Example: 3, 7, 11, … with 10 terms ends at 39 and adds up to 210.
FAQ
Is this calculator free?
Yes. No signup is needed and nothing you enter is stored.
Is the result exact?
Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.
Do my numbers leave my device?
No. The calculation runs in your browser.