Running Difference Calculator

A running difference is what you compute when you are working through a stock and subtracting each outflow as it happens, or when you are tracking a budget and want to know the remaining amount after each commitment. It is a small variation on the running sum — same structure, opposite sign — and shows up often enough that it deserves its own tool.

Running Difference Calculator does exactly that computation. Set an optional starting balance (or take the first value in your list as the start), paste the per-step deductions or transactions, and get a clean list of the remaining balance after each step, with min, max, mean, total consumption, overdraft detection and a chart view.

Underneath the buttons is the small amount of information the system actually requires — what a running difference represents, where negative values come in, why overdraft detection matters — plus practical guidance on how to interpret the result. Everything runs in your browser; nothing is uploaded.

• Optional starting balance: Set the initial amount explicitly, or take the first value in your list as the starting point.
• Per-step running difference: Every intermediate balance shown alongside the deduction that produced it, indexed for easy reference.
• Overdraft detection: Flags the first step at which the running difference crosses below zero — useful for budget and inventory checks.
• Statistics summary: Min, max, mean, count, total consumption and standard deviation computed once and shown next to the data.
• Line chart view: Visualise the running balance over time to spot when drain accelerated or halted, with negative-balance regions shaded.
• Three export formats: CSV (running difference), JSON array, and a plain text list with original value and balance together.
• Copy or download: Take what you compute without leaving the browser, with nothing uploaded to any server.

1. Set the starting balance. Optional — defaults to the first value in your list if you leave it blank.
2. Paste the deductions. Positive numbers are the amounts to subtract; paste one per line.
3. Set the rounding. Default is 4 decimal places, adjustable to your needs.
4. Read the per-step output. Every running balance is shown alongside the deduction that produced it.
5. Check the overdraft step. The summary flags the first step where the running balance goes negative, if any.
6. Open the chart view. A line view of the running balance makes drain acceleration and overdrafts obvious.
7. Copy or download the result. CSV for spreadsheets, JSON for code, plain text for documentation.

Example 1 — Inventory depletion. Start with a stock count of 1000. Each subsequent value is a shipment out. The running difference shows the stock level after each shipment. The chart shows when drain accelerated.

Example 2 — Budget consumption. Set the budget to 10000. Each value is a commitment. The running difference is the budget remaining after each commitment. The first negative step is the first commitment that exceeded the budget.

Example 3 — Fuel tank usage. Start with a full tank. Each subsequent value is a refill (negative — adds fuel) or a burn (positive — subtracts). The running difference is the fuel remaining after each event.

Example 4 — Subscription minutes. Start with a monthly minute budget. Each call subtracts its duration. The running difference shows minutes remaining after each call. Negative means you exceeded the plan.

Example 5 — Task burndown. Start with the total story points. Each value is the points completed in a sprint. The running difference is the remaining work — useful for burndown charts.

• Stop writing throwaway scripts: Get a clean running-difference table in one click from any list of numbers.
• Catch overdrafts early: The first negative step is flagged, so budget overruns and stockouts are visible at a glance.
• Trust the summary statistics: Min, max, mean, count and standard deviation calculated for the same list, so you have everything in one place.
• Match any consumer: CSV for spreadsheets, JSON for code, plain text for documentation.
• Free and private: No account, no watermark, nothing uploaded.