Sum Calculator
Enter numbers separated by commas to get their sum, count and average.
To sum a list of numbers, add them all together. This calculator totals any comma-separated list and also reports the count of values and their average — the sum divided by the count. It handles negative numbers and decimals.
How to Use This Calculator
Type the numbers you want to add, separated by commas. Spaces are fine, and you can mix whole numbers, decimals and negatives. The calculator returns the total, the count of how many numbers you entered, and their average.
It is handy for quickly totalling a set of figures — expenses, scores, measurements — without setting up a spreadsheet.
How the Calculation Works
The calculator reads your list, ignores anything that is not a valid number, and adds the values together for the sum. It counts how many valid numbers it found, and divides the sum by that count to give the average, also called the mean.
Because it processes the list as you type, the totals update instantly with each change.
sum = v₁ + v₂ + … + vₙ; average = sum ÷ count
Worked Example
Enter 3, 5, 7, 9. The sum is 3 + 5 + 7 + 9 = 24. There are 4 numbers, so the count is 4.
The average is 24 ÷ 4 = 6. Adding a negative works the same way: 3, 5, 7, 9, −4 sums to 20 across 5 numbers, for an average of 4.
Assumptions and Limitations
- Separate numbers with commas; spaces around them are ignored
- Non-numeric entries are skipped, not counted
- The average is the arithmetic mean (sum ÷ count)
- Very long lists are fine but are processed in the browser
When to Use a Sum Calculator
Students, teachers, and anyone with a list of numbers use this to get the total, count, and average at once. It is handy for adding up scores, expenses, measurements, or data points without a spreadsheet. Paste or type your numbers and read the sum and mean instantly.
Related Calculators
Discriminant Calculator
Find b² − 4ac and what it tells you about a quadratic's roots.
Open calculator →Common Denominator Calculator
Find the least common denominator of two fractions and rewrite them.
Open calculator →Distributive Property Calculator
Expand a(bx + c) using the distributive property, step by step.
Open calculator →Percentage Decrease Calculator
Find the percentage decrease between two values.
Open calculator →Frequently Asked Questions
How do I add a list of numbers?
Enter them separated by commas and the calculator totals them instantly. It also shows how many numbers there are and their average, so you get the sum, count and mean at once.
Can I sum negative numbers and decimals?
Yes. The calculator accepts negatives and decimals mixed freely in the list, adding them all correctly to give the total.
What is the average it shows?
It is the arithmetic mean — the sum divided by how many numbers you entered. For 3, 5, 7, 9 the sum is 24 and the average is 24 ÷ 4 = 6.
What happens if I type something that isn't a number?
Non-numeric entries are ignored and not counted, so a stray letter or symbol will not break the total. Only valid numbers are summed and counted.
Is my data saved anywhere?
No. The list is processed entirely in your browser and nothing is sent to a server or stored. Refreshing the page clears it.
Looking for a different calculator?
CalculatorPlus has free tools across finance, construction, math, health and more — each one showing the formula and a worked example.