Use the free Cumulative Sum Calculator below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Some questions are not about a single number but about how a total grows over time. How much have we sold so far this month? How many steps have I walked by Wednesday? How far through the budget are we after the third payment? A cumulative sum, also called a running total, answers that by adding each new value to everything before it, so every step in the list shows the total so far. The Cumulative Sum Calculator builds that running total from a pasted list in seconds.
This tool is built for everyday tracking, not for accountants alone. You do not need a spreadsheet, a formula, or an upload. Everything happens in your browser, on your own device. Your numbers never leave the page, and nothing is sent to a server. That privacy is useful when the list holds spending, income, or business sales you would rather keep to yourself.
To use it, paste a number list separated by commas, spaces, or line breaks. The sample already in the box shows the shape: five values that build to a final total. Press Build running totals and the result lists each step: the first value alone, then the first two added together, then the first three, and so on until the final total. Press Download CSV to save a two-column file with each original value beside its running total, ready to open in a spreadsheet.
Running totals reveal patterns that single values hide. A savings plan looks slow in the first months and then suddenly large, because each deposit adds to a growing pile. A project budget looks safe for the first few payments and then crosses a limit halfway through, and the running total shows exactly which payment crossed it. A fitness or reading goal shows at a glance whether you are ahead or behind, because the total so far can be compared with the target for that point in the plan.
The tool handles the awkward cases honestly. Negative values, such as refunds or withdrawals, subtract from the running total, which is exactly what they do to a real balance. Zeros leave the total unchanged, so a day with no sales still appears as a step, keeping the sequence aligned with the original list. Decimal values are kept as they are, so money with cents and measurements with fractions both work without rounding surprises, though very long decimals are shown as calculated.
A common mistake is to confuse a running total with a plain total. The plain total is only the last number in the running list, and it hides the journey. Two lists can share the same final total but tell different stories: one that grows steadily and one that jumps at the end. If you only need the final figure, add the list once. If you need to know when the total passed a threshold, or how it grew week by week, the running total is the right view, and this tool gives you every step.
Another mistake is to paste values in the wrong order. A running total depends on order in a way that a plain sum does not, because each step adds only what came before it. Always paste in time order, earliest first, and check that the first step equals your first value. If the steps look wrong, the order is almost always the cause, and re-pasting in the right order fixes it at once.
Small businesses use running totals for sales to date, charities use them for fundraising progress, and households use them for spending against a monthly budget. Teachers use them to show pupils how addition builds over a sequence, and runners use them for weekly mileage. The idea is the same everywhere: a total that grows step by step is easier to follow than a pile of separate numbers.
How to build running totals
- Paste your numbers in time order, earliest first.
- Press Build running totals.
- Read each step and the final total.
- Press Download CSV to save the value and running total columns.
Frequently asked questions
What is a running total? Each step adds the new value to all previous values, so every step shows the total so far.
Do negative values work? Yes. Refunds and withdrawals subtract from the running total, like a real balance.
Does order matter? Yes. Paste earliest first, because each step only includes what came before it.
Is my data uploaded? No. All addition happens in your browser.
Paste a list you track already, such as sales, savings, or steps, and watch the total grow step by step. The point where it crosses your target is usually the most interesting number in the list.