Calculate Hours in Excel

What this does

Excel stores a time as a fraction of a day: 06:00 is 0.25, 12:00 is 0.5. Subtracting two times therefore gives a fraction of a day, and the formatting decides what you see. The square brackets in [h]:mm are the critical part — plain h:mm resets to zero after 24 hours, so a 30-hour total displays as 6:00, which is the classic wrong timesheet. Multiplying the difference by 24 converts it to decimal hours (7.5 rather than 7:30), which is what payroll arithmetic needs. A shift crossing midnight makes the subtraction negative; =MOD(End-Start, 1) handles it by wrapping into the next day. And where the two moments fall on different DATES, store date and time together in one cell — subtracting a bare 09:00 on Tuesday from a bare 17:00 on Monday cannot possibly know a day passed. 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. For “calculate hours in excel”, the reliable version is a short checking loop, not just the first command that appears to work. Run it on a deliberately small range first, watch how the affected cells change, and only then apply the same setup to the full sheet. 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 is what makes a calculation you can defend to a CFO or an auditor useful in real work: repeatable, auditable, and not dependent on memory or luck.

A worked example

Start 09:15 in B2, end 17:45 in C2. =C2-B2 formatted as [h]:mm shows 8:30. =(C2-B2)*24 formatted as a number shows 8.5 — the figure to multiply by an hourly rate. A night shift with start 22:00 and end 06:00: =C2-B2 shows ###### or a negative; =MOD(C2-B2, 1) shows 8:00. Timesheet arithmetic fails in exactly two ways — the 24-hour wrap and the midnight crossing — and both are one formatting choice and one MOD away from being right. If there is any chance you will reuse this, drop it into a small template tab right now: a labelled input area on the left and the formula beside it, checked once against the tool above. Next time the same question comes up, the answer is a single paste away instead of a rebuild from memory.

In Google Sheets

If you are in Google Sheets rather than Excel, the good news is that the formula shown here is identical and the workflow barely changes — menus sit across the top instead of in a ribbon, and a few function names differ slightly, but anything you build here moves across with little or no rework. 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. The short version of “calculate hours in excel”: the answer is at the top of this page, the tool proves it on your own numbers, and the sections above explain why it holds so the next variation does not stump you. Excel rewards people who reference cells instead of typing values and who keep inputs separate from formulas, because that is what makes a result you can audit months later. Build it once, deliberately, with the live tool as a check, and you convert a one-off lookup into a reusable skill — which is the whole point of learning the why and not just the what.

Common mistakes

• Formatting a total as h:mm rather than [h]:mm, so anything over 24 hours silently wraps.
• Subtracting bare times across midnight and getting ###### or a negative number.
• Paying against a time value directly — 8:30 as a number is 0.354, so it must be multiplied by 24 first.
• Entering times as text, which right-alignment (or the lack of it) reveals immediately.
• Summing a column of daily durations without the bracket format, which is where the wrong weekly total comes from.

Frequently asked questions