How to Add Hours in Excel

What this does

Excel stores a time as a fraction of a day: 6:00 is 0.25, 12:00 is 0.5. Adding times is therefore ordinary arithmetic, and the whole difficulty is display. The standard h:mm format shows a clock time, so a total of 30 hours displays as 6:00 — it has silently dropped the whole day. The custom format [h]:mm tells Excel to let the hours accumulate past 24. To convert a time total into a decimal number of hours for a rate calculation, multiply by 24: =SUM(B2:B20)*24 formatted as a plain number gives 30.5, which times an hourly rate gives money. Times crossing midnight need =B2-A2+(B2<A2) so the negative half-day is corrected. Keep the inputs visible and clearly labelled and the whole thing stays auditable — anyone who opens the file later, including you, can see at a glance exactly what feeds the result and change one assumption without hunting through the formula. Treat “add hours in excel” as a small repeatable workflow rather than a one-off click you hope to remember next time. Use a small test block before the live file, so any surprise in the affected cells shows up while it is still harmless. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. That turns a layout choice that keeps the sheet readable and sortable into a method you can reuse, explain, and defend when the workbook leaves your screen.

A worked example

Daily hours in B2:B8 as 7:30, 8:15, 6:45, 8:00, 7:45, 4:30, 0:00. =SUM(B2:B8) with the default h:mm shows 18:45, which is wrong — the true total is 42:45. Select the cell, press Ctrl+1 ▸ Custom, enter [h]:mm, and it reads 42:45. For pay at €18.50/hour: =SUM(B2:B8)*24*18.5 formatted as currency gives €790.88. A shift from 22:00 to 06:00 is =B2-A2+(B2<A2) → 8:00, where a plain subtraction returns ####. Timesheets, shift totals and project hours all go wrong in the same two places — the 24-hour wrap and the missing ×24 — and both are one formatting decision away from correct. A practical tip before you scale it up: build it once on a small block of test data, confirm the number against the tool on this page, and only then point it at your real sheet. That one habit catches almost every mistake while it is still cheap to fix, long before a wrong figure reaches a report or a colleague.

In Google Sheets

Google Sheets handles this almost identically to Excel. The formula syntax above is the same, and the menu lives under a slightly different label rather than a ribbon tab. Use the platform toggle at the top of the page to switch every keyboard shortcut between Windows and Mac, and expect at most cosmetic differences in naming. Keep this page bookmarked for the next time the same question comes up. Better still, rebuild the example once in your own sheet — doing it yourself, with the tool above to check against, is what turns a copied formula into a technique you own. If you take one thing from this page on “add hours in excel”, make it the habit rather than the keystrokes: set the problem up with labelled inputs, reference those cells, and let Excel do the recomputing. Bookmark the page for the syntax, but do the example once in a blank sheet and check it against the tool above — five minutes of hands-on practice fixes the method in memory far better than re-reading, and it surfaces the small snags while they are still harmless. After that the technique is genuinely yours: faster than searching for it again, and reliable enough to drop into work that other people depend on.

Common mistakes

• Leaving the total in h:mm, which wraps at 24 hours and quietly under-reports the week.
• Typing 7.30 instead of 7:30, which Excel stores as the number seven-point-three, not seven and a half hours.
• Multiplying a time total directly by an hourly rate without the ×24, which produces a figure about 24 times too small.
• Subtracting an end time from a start time across midnight and getting ####, the display of a negative time.
• Mixing text entries like "8 hrs" into the column, which SUM ignores without warning.

Frequently asked questions