Formula gives a wrong number — Excel not calculating correctly
There's no error, no red triangle, no calculation warning — the formula returns a number and Automatic calculation is on. It's just the wrong number, because the formula is quietly reading different cells than you think, or ignoring some of the ones you meant to include.
Confirm the formula is actually the problem
First rule out calculation mode: check Formulas → Calculation Options is set to Automatic, and press Ctrl+Alt+F9 to force a full recalculation. If the number changes when you do that, it was a stale-cache issue rather than a wrong formula.
The most common real cause: numbers stored as text
SUM, AVERAGE, and most math functions silently ignore any cell where the number is actually stored as text — left-aligned by default, and often flagged with a small green triangle in the top-left corner. A range that looks like all numbers can have a handful of text-formatted values pasted in from a system export, and the total will be low by exactly those values with no error anywhere. Select the range and check the status bar's Sum/Count at the bottom — if Count is higher than the number of cells you'd expect to be numeric, some are text.
The second cause: a range that didn't grow
A formula like =SUM(A2:A50) stays fixed at row 50 forever. Insert new rows above row 50 and the range updates automatically — but insert them below row 50 (a very common way to add new transactions to the bottom of a list) and they're silently excluded from every formula that referenced the old fixed range. The formula still calculates, still shows a number, and gives no indication that new rows were left out.
How to check without re-deriving every formula by hand
Upload the file below to see the actual cell range each formula reads, alongside the cached result, and re-evaluate it live so you can compare what it currently computes against what it's supposed to include.