Tag expressions
Use tag expressions to create unique and dynamic watch faces. Tag expressions are conditions that let you change the rotation, placement, and opacity of a component based on tag values that represent watch data, such as the date and time, battery status, or steps. Your watch face changes dynamically as the tag value changes.
For example, you can create a watch face where an object on the screen moves vertically with every passing second, or you can create a watch face with objects that appear or disappear at certain times.
Enter tag expressions directly into the rotate, placement, and opacity properties input fields of a component.
Tags must be enclosed in square brackets ([ ]). To open the tag scripting dialog in Watch Face Studio, select Tags. In the scripting dialog, you can create longer tag expressions and search for the tags you want.

The available tags, their descriptions, and their value ranges are shown in the following tables.
Date and time
Tag | Definition | Range | Example |
---|---|---|---|
UTC_TS | Timestamp as UTC milliseconds from the epoch | 1256953732 | |
MSEC | Millisecond | 0 - 999 | 123 |
SEC | Second in minute | 0 - 59 | 12 |
SEC_Z | Second in minute with leading zero | 00 - 59 | 03 |
SEC_MSEC | Second in minute with millisecond | 0.0 - 59.999 | 1.234 |
SEC_IN_DAY | Second in day | 0 - 86,400 | 12,345 |
MIN | Minute in hour | 0 - 59 | 3 |
MIN_Z | Minute in hour with leading zero | 00 - 59 | 03 |
MIN_SEC | Minute in hour with second | 0.0 - 59.999 | 1.234 |
HOUR_0_11 | Hour in day (0-11) | 0 - 11 | 3 |
HOUR_0_11_Z | Hour in day (0-11) with leading zero | 00 - 11 | 03 |
HOUR_0_11_MIN | Hour in day (0-11) with minute | 0.0 - 11.999 | 1.234 |
HOUR_1_12 | Hour in day (0-12) | 1 - 12 | 3 |
HOUR_1_12_Z | Hour in day (0-12) with leading zero | 01 - 12 | 03 |
HOUR_1_12_MIN | Hour in day (0-12) with minute | 1.0 - 12.999 | 1.234 |
HOUR_0_23 | Hour in day (0-23) | 0 - 23 | 3 |
HOUR_0_23_Z | Hour in day (0-23) with leading zero | 00 - 23 | 03 |
HOUR_0_23_MIN | Hour in day (0-23) with minute | 0.0 - 23.999 | 1.234 |
HOUR_1_24 | Hour in day (1-24) | 1 - 24 | 3 |
HOUR_1_24_Z | Hour in day (1-24) with leading zero | 01 - 24 | 03 |
HOUR_1_24_MIN | Hour in day (1-24) with minute | 1.0 - 24.999 | 1.234 |
DAY_1_31 | Day in month (1-31) | 1 - 31 | 3 |
DAY_1_31_Z | Day in month (1-31) with leading zero | 01 - 31 | 13 |
DAY_1_31_HOUR | Day in month (1-31) with hour | 1.0 - 31.999 | 1.234 |
DAY_WEEK | Day of week | 1 (Sunday) - 7 (Saturday) | 3 |
DAY_WEEK_F | Day of week, full text | Sunday - Saturday | Wednesday |
DAY_WEEK_S | Day of week, abbreviated text | Sun - Sat | Wed |
DAY_IN_YEAR | Day in year | 1 - 365 | 123 |
DAYS_IN_MON | Days in the current month | 28 - 31 | 31 |
MON | Month in year | 1 - 12 | 3 |
MON_Z | Month in year with leading zero | 01 - 12 | 03 |
MON_F | Month in year, full text | January - December | November |
MON_S | Month in year, abbreviated text | Jan - Dec | Nov |
MON_DAY | Month with day | 1.0 - 12.999 | 11.111 |
YEAR | Year | 0000 - 9999 | 2021 |
YEAR_S | Abbreviated year, represented by last two digits | 00 - 99 | 21 |
YEAR_MON | Year with month | 2021.307 | |
WEEK_IN_YEAR | Week in year | 1-52 | 24 |
WEEK_IN_MON | Week in month | 1-5 | 2 |
IS_24H | Whether the system uses 24-hour format | 0 (12-hour), 1 (24-hour) | 0 |
IS_DST | Whether the system uses Daylight Saving Time | 0 (No), 1 (Yes) | 0 |
TMZN_ABB | Timezone abbreviation | PST | |
TMZN_OFS | Timezone offset | -12 - +14 | +9 |
TMZN_OFS_WITH_DST | Timezone offset, modified for Daylight Saving Time | -12 - +14 | -7 |
TMZN_ID | ID of timezone | Asia/Seoul | |
IS_AFTNOON | Whether the hour is before or after noon | 0 (AM), 1 (PM) | 0 |
AMPM_PO | Position of AM or PM string | -1 (Unknown), 0 (First), 1 (Last) | 0 |
AMPM | AM/PM string formatted with system locale | AM/PM | AM |
Setting information
Tag | Definition | Range | Example |
---|---|---|---|
LANG_LOC | String representation of the system locale object, consisting of language, country, variant, script, and extensions. For example, en_US. | ko_KR |
Device information
Tag | Definition | Range | Example |
---|---|---|---|
BATT_PER | Current battery percentage | 0 - 100 | 70 |
BATT_IS_CHARGE | Whether the battery is charging | 0 (No), 1 (Yes) | 1 |
BATT_IS_LOW | Whether the battery of the watch is low and not charging | 0 (No), 1 (Yes) | 0 |
BATT_TEM_C | Current battery Temperature (°C) | 28.8 | |
BATT_TEM_F | Current battery Temperature (°F) | 83.84 | |
UNREAD_NC | Count of unread notifications on the device | 3 |
Sensor data
Tag | Definition | Range | Example |
---|---|---|---|
IS_ACC | Whether the device has an accelerometer sensor | 0 (No), 1 (Yes) | 1 |
ACC_X | Acceleration on the X axis | ||
ACC_Y | Acceleration on the Y axis | ||
ACC_Z | Acceleration on the Z axis | ||
ACC_A_X | Acceleration angle on the X axis | -90.0 - 90.0 | |
ACC_A_Y | Acceleration angle on the Y axis | -90.0 - 90.0 | |
ACC_A_Z | Acceleration angle on the Z axis | -90.0 - 90.0 | |
ACC_A_XY | Acceleration angle X + angle Y | -180.0 - 180.0 |
Health data
Tag | Definition | Range | Example |
---|---|---|---|
HR | Heart rate | 0 - | 60 |
HR_Z | Heart rate with leading zero | 00 80 120 |
|
SC | Step count | 0 - | 1000 |
SC_GOAL | Step count goal | 1 - 20000 | 20000 |
SC_PER | Step count as percentage of step count goal | 0 - 100 |
Moon phase
Tag | Definition | Range | Example |
---|---|---|---|
MOON_PO | Position of moon phase | 0 - 28 (See below) | 14.5 |
MOON_TY | Type of moon phase | 0 - 7 (See below) | 2 |
MOON_TY_NAME | Name of moon phase | (See below) |
The [MOON_PO] tag has the following range definitions:
- 0-0.5: New moonon
- 0.5-6.5: Evening crescentnt
- 7: First quarterer
- 7.5-13.5: Waxing gibbousus
- 14: Full moonon
- 14.5-20.5: Waning gibbousus
- 21: Last quarterer
- 21.5-27.5: Morning crescentnt
- 27.5-28: New moon
The [MOON_TY] and [MOON_TY_NAME] tags have the following range definitions:
- 0: New moon
- 1: Evening crescent
- 2: First quarter
- 3: Waxing gibbous
- 4: Full moon
- 5: Waning gibbous
- 6: Last quarter
- 7: Morning crescent
Functions
Functions | Definition | Expression example | Output example |
---|---|---|---|
round(num) | Returns the closest integer to num. | round(1.6) | 2 |
floor(num) | Returns the greatest integer less than or equal to num. | floor(1.6) | 1 |
ceil(num) | Returns the smallest integer that is greater than or equal to num. | ceil(1.2) | 2 |
sin(num) | Returns the sine of num. | sin(1) | 0.84147096 |
cos(num) | Returns the cosine of num. | cos(1) | 0.5403023 |
tan(num) | Returns the tangent of num. | tan(1) | 1.5574077 |
abs(num) | Returns the distance from zero. | abs(-10) | 10 |
clamp(num, min, max) | Returns the value of clamping num between max and min. | clamp([ACC_A_X], -30, 60) | -30~60 |
numberFormat(form, num) | Transforms num into the format of form. form is made up of the following values: 0: Fills empty spaces with zero. #: Does not display places with no values. .: Indicates the position of the decimal point. |
(numberFormat("#.#", [SEC_MSEC])) (numberFormat("#.###", ([SEC_MSEC]*10))) (numberFormat("000.000", ([SEC_MSEC]*10))) (numberFormat("0000.000", ([SEC_MSEC]*10))) |
32.4 324.37 324.370 0324.370 |
asin(num) | Returns the arcsine function of num. | asin(0.841) | 1 |
acos(num)m | Returns the arccosine function of num. | acos(0.54) | 1 |
atan(num) | Returns the arctangent function of num. | atan(1.557) | 1 |
deg(num) | Converts num from radians to degrees. | deg(3.142) | 180 |
rad(num) | Converts num from degrees to radians. | rad(180) | 3.141 |
pow(base, exponent) | Returns the result of a base raised to an exponent. | pow(12, 2) | 144 |
Operators
Tag expressions support various operators that can modify the value of the tag expressions.
Arithmetic operators
Arithmetic operators are basic math functions. They perform a function between 2 values, which are also called operands.
Operator | Definition |
---|---|
+ | Addition |
- | Subtraction |
* | Multiplication |
/ | Quotient of division |
% | Remainder of division |
Examples
The following examples show how to use tags and arithmetic operations in a tag expression:
-
5 * [BATT_PER]
This returns the battery percentage multiplied by 5.
If the battery percentage is 7%, then the value returned is 35.
-
[SEC] / 3
This returns the quotient of seconds in a minute divided by 3.
If the number of seconds that have passed in the minute is 7, then the value returned is 2.33.
-
[SEC] % 3
This returns the remainder of seconds in a minute divided by 3.
If the number of seconds that have passed in the minute is 7, then the value returned is 1.
-
3 + 5 * [BATT_PER]
The battery percentage is multiplied by 5, then 3 is added.
If the battery percentage is 7%, then the value returned is 38.
Multiplication is performed first, because it takes precedence over
addition, and then 3 is added to the result: 3 + 5 * 7 → 3 + 35 → 38. -
(3 + 5) * [BATT_PER]
The addition operation in parentheses is performed first, then the result is multiplied by the battery percentage. If the battery percentage is 7%, then the value returned is 56.
Relational operators
Relational operators compare 2 values to determine their relationship, such as whether one is greater than, less than, or equal to the other. A comparison that is true returns a value of 1. A comparison that is false returns a value of 0.
Operator | Definition |
---|---|
< | Less than |
<= | Less than or equal to |
> | Greater than |
>= | Greater than or equal to |
== | Equal to |
!= | Not equal to |
Examples
Relational operations are sometimes combined with arithmetic operations. The following examples use only relational operations, or relational operations and arithmetic operations.
-
[BATT_PER] <= 15
If the battery percentage is less than or equal to 15%, [BATT_PER] <= 15 is true and returns 1.
If the battery percentage is greater than 15%, [BATT_PER] <= 15 is false and returns 0.
-
1000 * ([HRATE] < 100) + 120
If the heart rate is less than 100 bpm, [HRATE] < 100 is true and returns the value of 1. Next, multiply 1 by 1,000 and then add 120. The final value returned is 1,120.
If the heart rate is greater than or equal to 100 bpm, [HRATE] < 100 is false and returns the value of 0. Next, multiply 0 by 1,000 and then add 120. The final value returned is 120.
Logical operators
Logical operators combine the results of 2 or more relational operations and return a value of 1 (true) or 0 (false). Tag expressions support the logical operations AND and OR.
-
AND – represented by an asterisk (*)
Both relational operations must be true for the AND logical operator to return a value of 1 (true). Otherwise, the return value is 0 (false).
-
OR – represented by the plus sign (+)
One or more of the relational operations must be true for the OR logical operator to return a value of 1 (true). If both of the relational operations are false, then the return value is 0 (false).
The following table describes the results of logical operations:
Result of relational operation 1 | Result of relational operation 2 | Result of AND (*) (relational operation 1) * (relational operation 2) |
Result of OR (+) (relational operation 1) + (relational operation 2) |
---|---|---|---|
0 (false) | 0 (false) | 0 * 0 = 0 | 0 + 0 = 0 |
0 (false) | 1 (true) | 0 * 1 = 0 | 0 + 1 = 1 |
1 (true) | 0 (false) | 1 * 0 = 0 | 1 + 0 = 1 |
1 (true) | 1 (true) | 1 * 1 = 1 | 1 + 1 = 1 |
A logical operator is applied only if both operands—the values on either side of the operator—are relational operations. An arithmetic operator is applied if either of the operands is a number value.
Logical operation | Arithmetic operation | Arithmetic operation |
---|---|---|
Both operands are relational operations: (0 <= 1) * (1 < 2) Result: 1 |
One operand is a relational operation and the other is a value: (0 <= 1) * 120 Result: 120 |
Both operands are values: 1 * 120 Result: 120 |
This tag expression consists of 2 relational operations on either side of the operator (0<=1 and 1<2), so the logical operator is applied. Because both of the relational operations are true, the final result of this tag expression is 1 (true). | This tag expression consists of a relational operation (0<=1) and a number value (120), so the arithmetic operator is applied. The result of the relational operation is 1 (true) which is then multiplied by 120. The final result of this operation is 120. | This tag expression consists of 2 number values (1 and 120), so the arithmetic operator is applied. The result is 1 multiplied by 120, which returns a final result of 120. |
Ternary operators
Ternary operations have 3 operands: a conditional operation, then a result if the conditional operation is true, and then a result if the conditional operation is false. A conditional operation can be a relational or logical operation.
Ternary operations are presented in the following format:
conditional_operation? result_if_true: result_if_false
Examples
The following examples are used to set the opacity of an image on the watch face.
-
[BATT_PER] <= 20? 15: 100
This operation sets the opacity of an image on the watch face to 15 if battery percentage is less than or equal to 20%. Otherwise, it sets the opacity to 100.
-
([BATT_PER] >= 50) * ([BATT_PER] <= 75)? 100: 0
This example uses a logical operation for its conditional operation.
This sets the opacity of an image on the watch face to 100 if the battery percentage is greater than or equal to 50% and less than or equal to 75%. Otherwise, it sets the opacity to 0.
Nested ternary operations
Ternary operations can be nested within the result operand of another ternary operation.
For example, if you have 2 ternary operations (a? b: c) and (x? y: z), you can create the following nested ternary operations:
-
conditional_operation? (a? b: c): result_if_false
If
conditional_operation
is true, then check conditional operation a.If a is true, the result is b. If a is false, the result is c.
If
conditional_operation
is false, the result isresult_if_false
. -
conditional_operation? result_if_true: (x? y: z)
If
conditional_operation
is true, the result isresult_if_true
.If
conditional_operation
is false, then check conditional operation x.If x is true, the result is y. If x is false, the result is z.
-
conditional_operation? (a? b: c): (x? y: z)
If
conditional_operation
is true, then check conditional operation a.If a is true, the result is b. If a is false, the result is c.
If
conditional_operation
is false, then check conditional operation x.If x is true, the result is y. If x is false, the result is z.