Arithmetic Sequence Calculator
nth term and sum of an arithmetic series.
Enter your values
ⓘ Live results
Results
- Term 20
- 98
- Sum of first n terms
- 1010
- Common difference
- 5
- First terms
- 3, 8, 13, 18, 23, 28, 33, 38, 43, 48
Quick answer
In an arithmetic sequence each term adds a fixed common difference, so the nth term is a₁ + (n−1)d.
aₙ = a₁ + (n−1)d, Sₙ = n/2 (a₁ + aₙ)
How to use the Arithmetic Sequence Calculator
- 1Enter the first term of the sequence.
- 2Enter the common difference between terms.
- 3Enter which term number you want.
Worked example
Using the values the calculator loads with:
Inputs
- First term3
- Common difference5
- Term number20
Results
- Term 2098
- Sum of first n terms1010
- Common difference5
- First terms3, 8, 13, 18, 23, 28, 33, 38, 43, 48
Frequently asked questions
What if the difference is negative?
The sequence decreases; the formulas still work exactly the same.
How is this different from geometric?
Arithmetic adds a constant, geometric multiplies by a constant.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.