CAN bus tools · runs in your browser

CAN signal bit calculator

Pull one signal out of a CAN frame — start bit, length, byte order, sign, scale and offset, the same things a DBC file defines — and see exactly which bits it uses. Or type a value and get the bytes to send.

Examples:
Physical value
13.97V
1397 × 0.01 + 0
Raw (dec)
1397
Raw (hex)
0x0575
Raw (bin)
0000010101110101
Byte76543210Hex
0
0
7
0
6
0
5
0
4
0
3
0
2
0
1
1
0
01
1
0
15
1
14
1
13
1
12
0
11
1
10
0
9
1
LSB
75
2
0
MSB
0
22
0
21
0
20
0
19
1
18
0
17
1
16
05
3
1
31
1
30
1
29
1
28
1
27
1
26
1
25
1
24
FF
4
0
39
1
38
1
37
1
36
1
35
1
34
1
33
1
32
7F
5
1
47
1
46
1
45
1
44
1
43
1
42
1
41
1
40
FF
6
1
55
1
54
1
53
1
52
1
51
1
50
1
49
1
48
FF
7
1
63
1
62
1
61
1
60
1
59
1
58
1
57
1
56
FF
Encode a value into the bytes
Raw 1350
01 46 05 FF 7F FF FF FF

How it works

Bits are numbered byte × 8 + bit, with bit 0 the least significant bit of each byte. Intel (little endian) signals — NMEA 2000, J1939 and CANopen all use this — start at their least significant bit and continue upwards into the next byte. Motorola (big endian) signals start at their most significant bit, as DBC files give it, and continue towards the LSB and then into the next byte's top bit.

Physical value = raw × scale + offset. Signed signals are two's complement over the signal's own length. Encoding rounds to the nearest raw step and refuses values that don't fit.

Typical uses: a CANopen PDO from a motor controller whose mapping you have from the manual, a proprietary frame from a BMS, or checking your own firmware's packing.

Other CAN tools

CAN ID decoder
Priority, PGN, source and destination from any identifier
Open
CAN frame decoder
ID + data bytes → named fields with units
Open
CAN log analyzer
candump, PCAN, Yacht Devices, Actisense, Vector logs
Open
Sources & privacy

Everything is decoded in your browser — logs and frames are never uploaded. Message layouts come from these documents; where a source doesn't define something, the tools show the raw bytes rather than guess.

The NMEA 2000 definitions are derived from canboat, © 2009–2026 Kees Verruijt, under the Apache License 2.0. NMEA 2000® is a registered trademark of the National Marine Electronics Association; canboat's definitions are reverse-engineered, not the official NMEA database. Check critical values against your equipment's documentation.