CAN Bit Timing Calculator

Calculate generic CAN nominal bit timing from clock frequency, bitrate, and sample point targets. Compare top candidate combinations with error metrics.

CAN nominal timing calculator

Inputs

CAN clock frequency (MHz) Target nominal bitrate (kbps)

Target sample point (%) SJW mode

Prescaler minimum Prescaler maximum

Total TQ minimum Total TQ maximum

Candidate rows CAN FD data phase hint (kbps)

Best match

Actual nominal bitrate-

Bitrate error-

Actual sample point-

Sample point error-

Prescaler-

Total TQ-

TSEG1-

TSEG2-

SJW-

TQ clock-

One TQ time-

CAN FD note-

Enter CAN clock and bitrate targets to calculate timing candidates.

Top timing candidates

Rank	Bitrate	Bitrate error	Sample point	Sample error	Prescaler	Total TQ	TSEG1	TSEG2	SJW
No candidate yet.

Generic register snippet

What is CAN bit timing?

CAN bit timing splits one nominal bit into SyncSeg, TSEG1, and TSEG2 using a controller clock and prescaler. Matching timing across nodes is required for stable bus communication.

Time quantum, TSEG1 and TSEG2

Time quantum (TQ) is the smallest timing unit. Total bit time is 1 + TSEG1 + TSEG2 in TQ units. This calculator searches practical combinations and ranks them by error.

CAN sample point

Sample point is where the bit value is read inside each bit period. Typical nominal CAN settings are often around 75 to 87.5 percent.

CAN FD nominal and data phase

CAN FD uses separate nominal and data phase timing. This page focuses on nominal timing and gives a practical note for data phase planning.

Generic timing vs controller-specific registers

Different controllers use different register names and legal ranges. Use this as a first-order calculator, then map values to your specific MCU or controller.

CAN timing reference examples

Bitrate	Typical sample point	Common use	Notes
125 kbps	80%	Long or industrial bus	More tolerant timing in noisy environments
250 kbps	80%	Industrial CAN	Common automation speed
500 kbps	75-87.5%	Automotive and OBD projects	Very common nominal bitrate
1 Mbps	75-80%	Short bus	Requires strong wiring and termination
CAN FD data	60-80%	High-speed data phase	Controller-specific limits apply

FAQ

What is sample point in CAN?

Sample point is the position in the bit period where the controller reads the bus state. It is usually expressed as a percentage of the nominal bit time.

What are TSEG1 and TSEG2?

They are timing segments after SyncSeg that define propagation and phase adjustment windows. Their ratio strongly affects sample point and tolerance.

How do I choose CAN bitrate and sample point?

Start from common profiles (for example 500 kbps near 80 percent) and adjust based on bus length, node count, and controller limits.

Why do different CAN controllers use different register names?

Vendors expose the same timing concepts using different register layouts and bit names. Always map values to your controller datasheet.

Is this calculator the same as an MCP2515 CNF calculator?

No. This is a generic CAN timing calculator. For MCP2515-specific CNF1/CNF2/CNF3 values, use the dedicated MCP2515 tool.