What is the UUID of the Date Time characteristic?

0x2A08. The Bluetooth SIG's characteristic_uuids.yaml lists Date Time as 0x2A08 with the identifier org.bluetooth.characteristic.date_time. No file in the SIG's repository ties it to a service: the repository lists service and characteristic UUIDs separately. Weight Measurement, Body Composition Measurement, Glucose Measurement, CGM Session Start Time, Blood Pressure Measurement, Intermediate Cuff Pressure, Temperature Measurement and Intermediate Temperature refer to it in their own structure.

Are any Date Time fields optional?

No. Every field in the SIG's structure has a size that cannot be zero: Year (uint16, 2), Month (uint8, 1), Day (uint8, 1), Hours (uint8, 1), Minutes (uint8, 1) and Seconds (uint8, 1).

How many bytes is a Date Time value?

7 octets. Every field has a fixed size in the SIG's structure: Year at offset 0 (uint16, 2), Month at offset 2 (uint8, 1), Day at offset 3 (uint8, 1), Hours at offset 4 (uint8, 1), Minutes at offset 5 (uint8, 1) and Seconds at offset 6 (uint8, 1).

Date Time (0x2A08): byte layout

GATT characteristic · org.bluetooth.characteristic.date_time · read from the Bluetooth SIG’s repository on 2026-10-17 · commit 408f4a0 (2026-10-14)

Date Time is Bluetooth GATT characteristic 0x2A08, org.bluetooth.characteristic.date_time in the Bluetooth SIG's assigned numbers. The SIG's GATT Specification Supplement file lays its value out as 6 fields: Year, Month, Day, Hours, Minutes and Seconds. Every field has a fixed size, 7 octets in all.

UUID: 0x2A08
Identifier: org.bluetooth.characteristic.date_time
The SIG’s description: The Date Time characteristic is used to represent date and time.The structure of this characteristic is defined below.
Service the SIG’s files tie it to: None: no file in the repository lists this characteristic under a service.
Referenced by: Weight Measurement, Body Composition Measurement, Glucose Measurement, CGM Session Start Time, Blood Pressure Measurement, Intermediate Cuff Pressure, Temperature Measurement, Intermediate Temperature
Source file: gss/org.bluetooth.characteristic.date_time.yaml

Byte layout: 6 fields

In the order the SIG’s structure lists them. Type and size are as published; sizes count octets except where a struct is marked as sized in bits. The offset is printed only where every earlier field has a fixed size; where an earlier field can be absent or vary, the cell names what it depends on. “Present when” is read from the field’s own “Present if” line, shown in full in the field notes below.

Offset	Field	Type	Size	Present when	Unit
0	Year	`uint16`	2	Always (fixed size)	—
2	Month	`uint8`	1	Always (fixed size)	—
3	Day	`uint8`	1	Always (fixed size)	—
4	Hours	`uint8`	1	Always (fixed size)	—
5	Minutes	`uint8`	1	Always (fixed size)	—
6	Seconds	`uint8`	1	Always (fixed size)	—

Field notes

Each field’s text in the SIG’s file, line by line.

Year uint16 · 2: Year as defined by the Gregorian calendar. Valid range 1582 to 9999. A value of 0 means that the year is not known. All other values are Reserved for Future Use.
Month uint8 · 1: Month of the year as defined by the Gregorian calendar. Valid range 1 (January) to 12 (December). A value of 0 means that the month is not known. All other values are Reserved for Future Use.
Day uint8 · 1: Day of the month as defined by the Gregorian calendar. Valid range 1 to 31. A value of 0 means that the day of month is not known. All other values are Reserved for Future Use.
Hours uint8 · 1: Number of hours past midnight. Valid range 0 to 23. All other values are Reserved for Future Use.
Minutes uint8 · 1: Number of minutes since the start of the hour. Valid range 0 to 59. All other values are Reserved for Future Use.
Seconds uint8 · 1: Number of seconds since the start of the minute. Valid range 0 to 59. All other values are Reserved for Future Use.

Guides on this site

No guide on this site names 0x2A08 yet. The connected-devices guides cover pairing, subscribing and testing for the device types they do name.

Questions

What is the UUID of the Date Time characteristic?: 0x2A08. The Bluetooth SIG's characteristic_uuids.yaml lists Date Time as 0x2A08 with the identifier org.bluetooth.characteristic.date_time. No file in the SIG's repository ties it to a service: the repository lists service and characteristic UUIDs separately. Weight Measurement, Body Composition Measurement, Glucose Measurement, CGM Session Start Time, Blood Pressure Measurement, Intermediate Cuff Pressure, Temperature Measurement and Intermediate Temperature refer to it in their own structure.
Are any Date Time fields optional?: No. Every field in the SIG's structure has a size that cannot be zero: Year (uint16, 2), Month (uint8, 1), Day (uint8, 1), Hours (uint8, 1), Minutes (uint8, 1) and Seconds (uint8, 1).
How many bytes is a Date Time value?: 7 octets. Every field has a fixed size in the SIG's structure: Year at offset 0 (uint16, 2), Month at offset 2 (uint8, 1), Day at offset 3 (uint8, 1), Hours at offset 4 (uint8, 1), Minutes at offset 5 (uint8, 1) and Seconds at offset 6 (uint8, 1).

Source

Read on 2026-10-17 from gss/org.bluetooth.characteristic.date_time.yaml and assigned_numbers/uuids/characteristic_uuids.yaml in the Bluetooth SIG’s public repository (branch main, commit 408f4a0, committed 2026-10-14), by scripts/fetch-bluetooth-gatt.mjs. The file’s notice says it is proprietary to Bluetooth SIG, that furnishing it grants no licence, and that it is subject to change without notice; it is © Bluetooth SIG, Inc., and its text is quoted here for identification. Generated by AIFitnessAPI, which is not affiliated with Bluetooth SIG; the SIG’s file remains the authority. The full notice and the conventions used on these pages are on the reference hub.

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