CAN ID Calculator
Convert and analyze standard 11-bit and extended 29-bit CAN identifiers. View decimal, hexadecimal and binary representations and inspect J1939-style fields for extended identifiers.
What Is a CAN ID?
A CAN identifier is the arbitration identifier carried by a Controller Area Network frame. It identifies the message and participates in CAN bus arbitration.
Lower numerical identifier values have higher arbitration priority because dominant zero bits win over recessive one bits during arbitration.
Standard 11-Bit CAN IDs
A standard CAN frame uses an 11-bit identifier. This provides values from 0 through 2047.
Maximum: 0x7FF
Decimal maximum: 2047
An identifier such as 0x7DF can be represented as:
Decimal: 2015
Binary: 11111011111
Extended 29-Bit CAN IDs
The extended CAN frame format uses a 29-bit identifier. The valid unsigned identifier range is 0 through 536,870,911.
1FFFFFFF hex
Decimal: 536870911
Extended identifiers provide a much larger identifier space and are used by protocols and applications that require additional message addressing or classification information.
CAN ID Decimal, Hex and Binary Conversion
Decimal, hexadecimal and binary are simply different representations of the same identifier bits.
Decimal: 291
11-bit binary: 00100100011
Hexadecimal is especially convenient for CAN analysis because it provides a compact representation of binary values.
CAN Arbitration Priority
CAN uses bitwise arbitration when multiple nodes attempt to transmit at the same time. A dominant zero bit overrides a recessive one bit.
As a result, an identifier with a lower numerical value generally wins arbitration over a higher identifier value when competing under the applicable CAN arbitration rules.
has higher arbitration priority than
CAN ID 0x500
11-Bit vs 29-Bit CAN Identifier
| Identifier Type | Width | Maximum Hex | Maximum Decimal |
|---|---|---|---|
| Standard CAN | 11 bits | 7FF | 2047 |
| Extended CAN | 29 bits | 1FFFFFFF | 536870911 |
J1939 29-Bit Identifier Layout
SAE J1939 uses the 29-bit CAN identifier as a structured field containing priority and message-addressing information.
Reserved: 1 bit
Data Page: 1 bit
PDU Format: 8 bits
PDU Specific: 8 bits
Source Address: 8 bits
The calculator can display these fields when an extended 29-bit identifier is selected.
J1939 Priority
The upper three bits of a J1939 identifier contain the priority field, giving values from 0 through 7.
Priority is one component of the full CAN identifier and influences message arbitration.
J1939 PDU Format and PDU Specific
The PDU Format field determines whether a J1939 message uses the PDU1 or PDU2 format.
PF 240 or greater: PDU2
For PDU1 messages, the PDU Specific field commonly acts as a destination address. For PDU2 messages, it contributes to the group extension portion of the PGN.
J1939 PGN Calculation
The Parameter Group Number identifies the message group in J1939. Its construction depends on the PDU Format value.
PDU2: PGN uses DP, PF and PS
This calculator performs that basic J1939-style PGN extraction when extended-ID analysis is enabled.
CAN ID vs CAN Payload
The identifier and payload serve separate purposes.
| CAN Component | Purpose |
|---|---|
| CAN ID | Message identification and arbitration |
| CAN Payload | Carries application data and signals |
This calculator analyzes the identifier only. Signal extraction belongs to the CAN Bus Data Decoder.
Important CAN ID Notes
The largest valid standard ID is 0x7FF.
The largest valid extended ID is 0x1FFFFFFF.
Lower numerical CAN IDs generally have higher arbitration priority.
J1939-style analysis should be used only when the 29-bit identifier actually follows J1939 field conventions.
Not every extended CAN network is J1939.
This calculator does not decode payload data or determine manufacturer-specific message meaning.