Fiber Transceiver Distance Chart: SR, LR, ER, ZR, ZR+
Fiber optic transceivers come in different reach categories defined by IEEE 802.3 standards. Understanding the distance specifications helps you select the right transceiver for your network link.
SR (Short Reach)
SR transceivers use multimode fiber (OM2/OM3/OM4/OM5) and support distances from 100m to 600m depending on fiber type. OM4 multimode fiber achieves 400m at 10G and 150m at 100G. SR modules are the most cost-effective choice for data center intra-rack and inter-rack connections.
LR (Long Reach)
LR transceivers operate over single-mode fiber (OS2) and support 10km reach at 10G. LR4 modules for 40G/100G support 10km using CWDM wavelengths. These are the standard choice for campus and metro area network links.
ER (Extended Reach)
ER transceivers support 40km reach over single-mode fiber. ER4 modules for 40G/100G also achieve 40km. These require more optical power and are used for longer metro and regional network connections.
ZR and ZR+ (Ultra Long Reach)
ZR transceivers support 80km reach, while ZR+ can reach 120km or more. ZR optics use coherent technology for 100G/400G/800G speeds. These are essential for long-haul and submarine network applications.
Selection Guide
Choose SR for links under 600m (data center), LR for 10km links (campus/metro), ER for 40km links, and ZR for 80km+ links (long-haul). Using longer-reach optics than needed adds unnecessary cost without performance benefit. Always match the transceiver reach to your actual link distance.
