How to Combine a Date and a Time into One Value in Excel

Add a date column to a time column to get full timestamps, calculate overnight arrivals, and measure hours between departures.

You will learn to

• Combine a date and a time into one timestamp
• Add a duration that crosses midnight
• Measure hours between two timestamps

How it works

A date is a whole number and a time is a fraction, so combining them is plain addition: =B2+C2 turns 3/9/2026 and 7:45 AM into 3/9/2026 7:45 AM. Format the result with a date-and-time style such as m/d/yyyy h:mm AM/PM to see both parts. (Joining them with & would create text instead.)

Once date and time live in one value, overnight maths just works. Adding a flight duration in hours (÷24) rolls into the next day automatically, and subtracting two timestamps then multiplying by 24 gives the hours between them, even across midnight.

=B2+C2