Math & Scientific
Arithmetic Sequence Calculator
Arithmetic Sequence: it uses the arithmetic-sequence formulas: nth term aₙ = a₁ + (n−1)d and sum Sₙ = n/2 · (a₁ + aₙ). Worked through below with real figures, and the calculator repeats the working on your own inputs — free, on-device, instant.
Enter your first term, common difference and term number and Arithmetic Sequence Calculator works out the result with the standard method — fast, free and private, with no sign-up or uploads.
About this calculator
Arithmetic Sequence is easiest to get wrong in the setup, not the arithmetic. It uses the arithmetic-sequence formulas: nth term aₙ = a₁ + (n−1)d and sum Sₙ = n/2 · (a₁ + aₙ). It matters when you need the exact relationship checked quickly rather than worked through by hand. The worked example on this page (For first term 3 and common difference 5, the 10th term = 3 + (10−1) × 5 = 48 .) shows the full substitution; the calculator above runs the same working on your own numbers, in your browser, with nothing uploaded.
How to use
- Enter the first term (a), the common difference (d), and how many terms (n).
- Press Calculate to run the arithmetic sequence calculator.
- Read the result: the nth term, the sum of the first n terms, and the first few terms.
- Press Reset to clear the arithmetic sequence calculator and start again.
Why use Arithmetic Sequence Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Accurate
Based on standard, well-established formulas.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Honest disclaimers wherever browser limits or regional rules apply.
Common uses
Arithmetic Sequence in statistics and data coursework
Use it for quick mental-math cross-checks
Use it for homework and assignment checks
Arithmetic Sequence in tutoring and teaching sessions
Use it when comparing two different methods
Use it when revising for exams
Technical notes
Arithmetic Sequence Calculator uses the arithmetic-sequence formulas: nth term aₙ = a₁ + (n−1)d and sum Sₙ = n/2 · (a₁ + aₙ).
Inputs are taken exactly as entered, so check for typos before trusting an answer.
Results are rounded for display; the underlying calculation keeps full precision.
FAQ
What is an arithmetic sequence?
A list of numbers where each term increases by the same fixed amount, called the common difference (d).
How does the Arithmetic Sequence Calculator find the nth term?
Use aₙ = a₁ + (n−1)d, where a₁ is the first term and d is the common difference — the calculator does this for you.
Can it find the sum of the sequence?
Yes. It returns the sum of the first n terms using n × (a₁ + aₙ) ÷ 2, along with the nth term and a preview.
Does the Arithmetic Sequence Calculator send my data to a server?
No — the Arithmetic Sequence Calculator runs entirely in your browser, so the numbers you enter never leave your device.
Worked example
For first term 3 and common difference 5, the 10th term = 3 + (10−1) × 5 = 48.