How to Use AutoSum in Excel (Alt+= / Shift+Cmd+T)

AutoSum is the fastest way to insert a SUM formula without typing it manually, triggered by Alt+= on Windows or Shift+Cmd+T on Mac. Select an empty cell below or to the right of a column or row of numbers, press the shortcut, and Excel proposes a SUM formula with a guessed range — visually highlighted with a marching-ants border so you can see exactly which cells it intends to add before committing. **Why the guess can be wrong**: AutoSum guesses the range by looking for the nearest unbroken run of numeric cells. If there's a blank cell, a text label, or a subtotal row partway up the column, the guessed range stops there rather than spanning your entire intended dataset. This is the single most common AutoSum mistake — pressing Alt+= and then immediately Enter without checking the highlighted range, only to discover the sum silently excluded the top half of the column. Always glance at the highlighted range before confirming. **Selecting multiple cells first**: If you select a whole row of empty cells at the bottom of several columns and then press Alt+=, Excel inserts a separate SUM formula in each selected cell simultaneously, each one correctly referencing its own column — a fast way to total an entire table in one keystroke rather than repeating AutoSum column by column. **The dropdown arrow next to AutoSum** (visible on the ribbon, not the keyboard shortcut) also offers Average, Count, Max, and Min as one-click alternatives, but those don't have their own dedicated default keyboard shortcuts — only the Sum function is bound to a key combination. **Alternative methods**: Typing =SUM( and manually selecting or typing the range achieves the same result with full control over the exact range, which is preferable for ranges that AutoSum's guesswork won't get right anyway — for instance, summing non-adjacent cells, or summing a range that deliberately includes a blank row you want counted as zero. **Related shortcuts**: Ctrl+` toggles formula view, useful immediately after AutoSum if you want to double-check the actual range syntax it inserted rather than just trusting the visual highlight. F4, used while editing the AutoSum formula, can lock the range as an absolute reference if you intend to copy the formula elsewhere without the range shifting. **Keyboard-only confirmation habit**: rather than pressing Enter immediately after Alt+=, get in the habit of glancing at the marching-ants border first, and only then pressing Enter — this half-second pause is the single easiest way to avoid the most common AutoSum mistake without slowing down your actual workflow in any meaningful way. **AutoSum across a 2D block**: selecting a rectangular range that includes both a blank row below your numbers and a blank column to the right, then pressing Alt+=, fills in both the row totals and column totals simultaneously in one keystroke — a lesser-known trick that handles what would otherwise require running AutoSum separately for rows and then again for columns. **Mistake to avoid with hidden rows**: if a row within your intended range is hidden (rather than genuinely blank), AutoSum still includes it in the guessed range and in the resulting sum, unlike some other Excel functions that specifically ignore hidden rows — if your dataset relies on hiding rows to represent excluded data, AutoSum's default SUM formula won't respect that, and you'd need SUBTOTAL with the appropriate function code instead to exclude hidden rows from the total.