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CWDM and DWDM Channel Wavelength Chart (ITU Grid)

CWDM and DWDM multiplex several wavelengths onto one fiber pair. This chart lists the 18 CWDM wavelengths and the 40 DWDM C-band channels from C21 to C60 on the 100 GHz grid, so you can match mux ports, transceivers and filter modules.

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Grid	Channel	Frequency (THz)	Wavelength (nm)	Band
CWDM 20 nm	1270	236.1	1270	O
CWDM 20 nm	1290	232.4	1290	O
CWDM 20 nm	1310	228.8	1310	O
CWDM 20 nm	1330	225.4	1330	O
CWDM 20 nm	1350	222.1	1350	O
CWDM 20 nm	1370	218.8	1370	E
CWDM 20 nm	1390	215.7	1390	E
CWDM 20 nm	1410	212.6	1410	E
CWDM 20 nm	1430	209.6	1430	E
CWDM 20 nm	1450	206.8	1450	E
CWDM 20 nm	1470	203.9	1470	S
CWDM 20 nm	1490	201.2	1490	S
CWDM 20 nm	1510	198.5	1510	S
CWDM 20 nm	1530	195.9	1530	C
CWDM 20 nm	1550	193.4	1550	C
CWDM 20 nm	1570	191.0	1570	L
CWDM 20 nm	1590	188.5	1590	L
CWDM 20 nm	1610	186.2	1610	L
DWDM 100 GHz	C21	192.1	1560.61	C
DWDM 100 GHz	C22	192.2	1559.79	C
DWDM 100 GHz	C23	192.3	1558.98	C
DWDM 100 GHz	C24	192.4	1558.17	C
DWDM 100 GHz	C25	192.5	1557.36	C
DWDM 100 GHz	C26	192.6	1556.55	C
DWDM 100 GHz	C27	192.7	1555.75	C
DWDM 100 GHz	C28	192.8	1554.94	C
DWDM 100 GHz	C29	192.9	1554.13	C
DWDM 100 GHz	C30	193.0	1553.33	C
DWDM 100 GHz	C31	193.1	1552.52	C
DWDM 100 GHz	C32	193.2	1551.72	C
DWDM 100 GHz	C33	193.3	1550.92	C
DWDM 100 GHz	C34	193.4	1550.12	C
DWDM 100 GHz	C35	193.5	1549.32	C
DWDM 100 GHz	C36	193.6	1548.51	C
DWDM 100 GHz	C37	193.7	1547.72	C
DWDM 100 GHz	C38	193.8	1546.92	C
DWDM 100 GHz	C39	193.9	1546.12	C
DWDM 100 GHz	C40	194.0	1545.32	C
DWDM 100 GHz	C41	194.1	1544.53	C
DWDM 100 GHz	C42	194.2	1543.73	C
DWDM 100 GHz	C43	194.3	1542.94	C
DWDM 100 GHz	C44	194.4	1542.14	C
DWDM 100 GHz	C45	194.5	1541.35	C
DWDM 100 GHz	C46	194.6	1540.56	C
DWDM 100 GHz	C47	194.7	1539.77	C
DWDM 100 GHz	C48	194.8	1538.98	C
DWDM 100 GHz	C49	194.9	1538.19	C
DWDM 100 GHz	C50	195.0	1537.40	C
DWDM 100 GHz	C51	195.1	1536.61	C
DWDM 100 GHz	C52	195.2	1535.82	C
DWDM 100 GHz	C53	195.3	1535.04	C
DWDM 100 GHz	C54	195.4	1534.25	C
DWDM 100 GHz	C55	195.5	1533.47	C
DWDM 100 GHz	C56	195.6	1532.68	C
DWDM 100 GHz	C57	195.7	1531.90	C
DWDM 100 GHz	C58	195.8	1531.12	C
DWDM 100 GHz	C59	195.9	1530.33	C
DWDM 100 GHz	C60	196.0	1529.55	C

CWDM channels are the ITU-T G.694.2 grid at 20 nm spacing; the Channel column shows the nominal wavelength. DWDM rows are the ITU-T G.694.1 100 GHz grid anchored at 193.1 THz, wavelength = 299792.458 / frequency in THz. Frequencies are rounded.

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How to use the chart

Search a wavelength or channel number to get the matching row. For CWDM, pick the wavelengths that your transceivers and mux support; many 8-channel muxes use 1470 to 1610 nm. For DWDM, match the C-number on the transceiver label to the mux port and check that the frequency is on the grid of your mux and amplifier.

The math behind the grid

Wavelength in nanometers equals 299792.458 divided by frequency in terahertz. The DWDM 100 GHz grid is anchored at 193.1 THz (about 1552.52 nm), and channel numbers on this table count 100 GHz steps from 190.0 THz, so C31 is 193.1 THz. Higher frequency means shorter wavelength, so C60 sits at the short end of the C-band near 1529.55 nm.

100 GHz spacing is about 0.8 nm near 1550 nm.
CWDM spacing is 20 nm, so uncooled lasers can drift without crosstalk.
50 GHz grids insert a channel between each 100 GHz pair.

Common mistakes

Do not mix CWDM and DWDM filters on the same port, and do not use 1470 to 1610 nm CWDM optics through a mux that passes only the C-band. Confirm the O-band 1270 to 1330 nm CWDM channels are supported by your fiber; legacy fiber with a water peak near 1383 nm loses E-band channels. Note that channel-numbering conventions differ between vendors, so always confirm the wavelength.

Frequently Asked Questions

How many CWDM channels are there?

The ITU-T G.694.2 grid defines 18 channels from 1271 to 1611 nm at 20 nm spacing. In practice vendors label them 1270, 1290 and so on up to 1610 nm, and most muxes use 4, 8 or 16 of them.

What is the DWDM 100 GHz grid?

It is the ITU-T G.694.1 frequency plan where channels are 100 GHz apart, anchored at 193.1 THz. Near 1550 nm that is roughly 0.8 nm of wavelength spacing per channel.

How do I convert THz to nm?

Divide 299792.458 by the frequency in THz. For 193.1 THz the result is about 1552.52 nm. The relation is inverse, so higher frequency gives a shorter wavelength.

Can CWDM and DWDM run together?

Yes, with a CWDM mux that has a pass port in the C-band, DWDM channels can be added behind it. Plan the loss of both mux stages in the link power budget.

Netray can map optical module part numbers and wavelengths to ERP item masters so planners see the right optics for each build.

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