Convert an absolute channel number into a DMX universe and local channel, or calculate the absolute number from a universe/channel pair. This tool uses one-based numbering: universe 1 starts at absolute channel 1.
Absolute channel to universe
Universe and channel to absolute number
How the calculation works
Each universe provides up to 512 channel slots. This converter groups absolute channel numbers into blocks of 512.
- Universe = floor((absolute channel − 1) ÷ 512) + 1
- Local channel = ((absolute channel − 1) remainder 512) + 1
- Absolute channel = (universe − 1) × 512 + local channel
Worked examples and boundary checks
| Absolute channel | Universe | Local channel |
|---|---|---|
| 1 | 1 | 1 |
| 512 | 1 | 512 |
| 513 | 2 | 1 |
| 525 | 2 | 13 |
| 1024 | 2 | 512 |
For absolute channel 525, subtract 1 to get 524. One complete block of 512 precedes it, so the universe is 2. The remainder is 12; adding 1 gives local channel 13. In reverse: (2 − 1) × 512 + 13 = 525.
This is numbering, not fixture patching
A fixture with F channels must start at or before 513 − F to fit within one universe. A 20-channel fixture starting at local channel 500 would need channels 500–519 and does not fit. This converter does not split that fixture or automatically route its remaining channels elsewhere.
For a non-overlapping list of fixture start addresses and channel ranges, use the DMX channel patch planner. For directly encoded switch positions, use the DMX DIP switch calculator.
Controller and network conventions
Some consoles or network interfaces display zero-based universe numbers or use protocol-specific identifiers. This tool’s universe 1 means the first block in a one-based numbering scheme. Check the controller or node manual before entering the result into its routing settings.
The conversion alone does not establish which output carries a universe. Assign the universe to the intended physical or network output separately.
Frequently asked questions
Why does channel 513 become universe 2, channel 1?
The first 512 absolute channels fill universe 1. The next absolute channel begins the second block.
Can I use local channel 0 or 513?
No. In this tool, a local DMX channel must be a whole number from 1 through 512. The universe number also starts at 1.
Does the absolute number go into a fixture’s DIP switches?
Usually the fixture needs a local start address within its routed universe. The absolute number is a numbering convenience. Follow the fixture manual for its address encoding.
Reference
CHAUVET DJ DMX Primer explains DMX channels, start addresses, and addressing. The block-number formulas above are the arithmetic convention used by this converter.