Epoch Converter for Excel and Google Sheets — Formulas That Work

Excel does not natively understand Unix timestamps. But two simple formulas handle conversion in both directions. This guide gives you copy-paste formulas that work in Excel and Google Sheets, plus tips for timezones and milliseconds.

Epoch to Date Formula (Excel + Google Sheets)

If cell A1 contains a Unix timestamp in seconds (10 digits like 1712345678):

=(A1/86400)+DATE(1970,1,1)

If your timestamp is in milliseconds (13 digits like 1712345678000):

=(A1/86400000)+DATE(1970,1,1)

Format the result cell as Date/Time to see the readable date.

Date to Epoch Formula (Excel + Google Sheets)

If cell A1 contains a date:

=(A1-DATE(1970,1,1))*86400

This gives seconds since epoch. For milliseconds, multiply by 1000:

=(A1-DATE(1970,1,1))*86400000

Why 86400?

There are 86,400 seconds in a day (60 seconds × 60 minutes × 24 hours). Excel stores dates as a serial number representing days. Dividing a timestamp by 86,400 converts seconds to days, which Excel understands.

Handling Timezones

Unix timestamps are always UTC. Excel dates have no timezone info. If you need local time:

=(A1/86400)+DATE(1970,1,1)+(timezone_offset/24)

Timezone	Offset	Formula Addition
UTC	0	+(0/24)
EST (UTC-5)	-5	-(5/24)
CST (UTC-6)	-6	-(6/24)
PST (UTC-8)	-8	-(8/24)
IST (UTC+5:30)	+5.5	+(5.5/24)
JST (UTC+9)	+9	+(9/24)

Bulk Conversion

Put the formula in one cell, then drag it down to convert an entire column of timestamps. This is where Excel beats a browser tool — for hundreds or thousands of timestamps, a spreadsheet formula applied to a column is faster.

For one-off conversions during debugging, the Timestamp Converter is faster than opening a spreadsheet.

Common Gotchas

• Result shows a number, not a date: Format the cell as Date/Time (right-click → Format Cells → Date)
• Date is off by hours: Timezone issue. Add the UTC offset to the formula.
• Date is wildly wrong: Check if your timestamp is in seconds or milliseconds. Wrong divisor = wrong date.
• Negative timestamp: Dates before 1970 have negative timestamps. The formula still works.

Related: CSV to JSON for converting spreadsheet data, JSON Formatter for API debugging.