Proofing and resting steps run on the clock, so you need to add minutes to a start time and see exactly when each stage finishes. Excel times are fractions of a day, so the math is simple once you know the divisor.
Excel stores a full day as 1.0, so one minute is 1/1440 of that.
The example
Dough goes in to proof at 6:00 AM for 90 minutes.
| A | B | |
|---|---|---|
| 1 | Label | Value |
| 2 | Start time | 6:00 AM |
| 3 | Proof minutes | 90 |
| 4 | Finish time | 7:30 AM |
The formula
Convert minutes to a day fraction and add:
How it works
Why dividing by 1440 works:
- Excel stores time as a fraction of a 24-hour day, where 1.0 is a whole day.
- A day has 24 × 60 = 1440 minutes, so one minute is 1/1440.
B3/1440turns 90 minutes into the day fraction 0.0625 (1.5 hours).- Adding it to the 6:00 AM start gives 7:30 AM — just format the cell as time.
Alternatively, =B2+TIME(0,B3,0) adds the minutes without remembering 1440.
Try it: interactive demo
Enter a start hour and proof minutes — see the finish time.
Variations
Add minutes with TIME
TIME builds a duration directly, no divisor to remember.
Total proof in hours
Divide the minutes by 60 for a decimal-hours readout.
Pitfalls & errors
If the finish shows as a decimal like 0.3125, set the cell number format to Time.
If a stage crosses midnight, use MOD(B2+B3/1440,1) to wrap the result back into a 24-hour clock.
Practice workbook
Frequently asked questions
Why divide minutes by 1440?
Can I just use TIME?
What if proofing finishes after midnight?
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