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Français Reach tables: how far each optic goes on each fibre
"How far does SR go on OM3?" is the most common lookup in optics. The answer is a standard figure that assumes worst-case fibre, connectors within budget and the specified BER (with FEC where the PMD requires it). These tables collect the standard reaches for Ethernet, Fibre Channel, InfiniBand and PON, plus the cable lengths that replace optics inside a rack. Real plant with clean connectors often goes further; design to the standard figure, not to luck.
Ethernet, multi-mode (850 nm unless noted)
| PMD | OM1 (62.5 µm) | OM2 | OM3 | OM4 | OM5 | Standard |
|---|---|---|---|---|---|---|
| 1000BASE-SX | 275 m | 550 m | 550 m (≈ 800–1 000 m practical) | 550 m | 550 m | 802.3 Cl. 38 |
| 1000BASE-LX on MMF (1310 nm, mode-conditioning cord) | 550 m | 550 m | 550 m | 550 m | — | Cl. 38 |
| 10GBASE-SR | 33 m | 82 m | 300 m | 400 m | 400 m | Cl. 52 |
| 10GBASE-LRM (1310 nm) | 220 m | 220 m | 220 m | 220 m | — | Cl. 68 |
| 10GBASE-USR (vendor) | — | — | 100 m | 100 m | — | vendor |
| 25GBASE-SR | — | — | 70 m | 100 m | 100 m | Cl. 112 |
| 40GBASE-SR4 (MPO-12) | — | — | 100 m | 150 m | 150 m | Cl. 86 |
| 40G eSR4 / 40G BiDi SR-BD (vendor) | — | — | 300 m / 100 m | 400 m / 150 m | — / 150 m | vendor |
| 50GBASE-SR | — | — | 70 m | 100 m | 100 m | Cl. 138 |
| 100GBASE-SR10 (MPO-24) | — | — | 100 m | 150 m | 150 m | Cl. 86 |
| 100GBASE-SR4 (MPO-12) | — | — | 70 m | 100 m | 100 m | Cl. 95 |
| 100GBASE-SR2 (2 × 50G) | — | — | 70 m | 100 m | 100 m | Cl. 138 |
| 100G SWDM4 / 100G BiDi SRBD (LC duplex) | — | — | 75 m / 70 m | 100 m | 150 m | MSA / vendor |
| 100GBASE-SR1 / VR1 (100G per lane) | — | — | — | 100 m / 50 m | 100 m / 50 m | Cl. 167 (802.3db) |
| 200GBASE-SR4 | — | — | 70 m | 100 m | 100 m | Cl. 138 |
| 200GBASE-SR2 / VR2 | — | — | — | 100 m / 50 m | 100 m / 50 m | Cl. 167 |
| 400GBASE-SR16 (MPO-32) | — | — | 70 m | 100 m | 100 m | Cl. 123 |
| 400GBASE-SR8 (MPO-16 / 2 × MPO-12) | — | — | 70 m | 100 m | 100 m | Cl. 138 (802.3cm) |
| 400GBASE-SR4.2 (BiDi, MPO-12) | — | — | 70 m | 100 m | 150 m | Cl. 150 |
| 400GBASE-SR4 / VR4 | — | — | — | 100 m / 50 m | 100 m / 50 m | Cl. 167 |
| 800GBASE-SR8 / VR8 | — | — | — | 100 m / 50 m | 100 m / 50 m | 802.3df |
Multi-mode reach is set by modal bandwidth and, at 25G+ per lane, by the receiver's dispersion tolerance — not by attenuation (Fibre types).
Ethernet, single-mode
| PMD | Reach | Wavelengths | Notes |
|---|---|---|---|
| 1000BASE-LX / LX10 | 5 km / 10 km | 1310 | most "LX" products are 10 km |
| 1000BASE-EX / ZX / EZX (vendor) | 40 / 80 / 120–160 km | 1310 / 1550 / 1550 | non-IEEE |
| 1000BASE-BX10 | 10 km | 1310/1490 BiDi | 20/40/80 km variants vendor |
| 10GBASE-LR | 10 km | 1310 | Cl. 52 |
| 10GBASE-ER | 40 km | 1550 | Cl. 52; watch Rx overload on short links |
| 10GBASE-ZR (vendor) | 80 km | 1550 | often APD receiver |
| 10G BiDi (vendor) | 10 / 20 / 40 / 60 / 80 km | 1270/1330, 1490/1550 | pairs must match |
| 10G CWDM / DWDM | 40 / 80 km (120 km with amplification) | per grid | CWDM, DWDM |
| 25GBASE-LR / ER | 10 / 40 km | 1310 / 1550 | Cl. 114 |
| 40GBASE-LR4 / ER4 | 10 / 40 km | LAN-WDM 4 λ | Cl. 87 |
| 40GBASE-FR | 2 km | 1550 serial | Cl. 89 |
| 40G PSM4 (MSA) | 10 km | 1310 × 4 fibres (MPO) | — |
| 50GBASE-FR / LR / ER | 2 / 10 / 40 km | 1310 / 1550 | Cl. 139 |
| 100GBASE-DR | 500 m | 1310 | Cl. 140 |
| 100G PSM4 (MSA) | 500 m (2 km some) | 1310 × 4 fibres | MPO-12 |
| 100G CWDM4 (MSA) / CLR4 | 2 km | 1271–1331 × 4 | LC duplex |
| 100G 4WDM-10 / -20 / -40 (MSA) | 10 / 20 / 40 km | LAN-WDM / CWDM | — |
| 100GBASE-FR1 / LR1 (100G Lambda) | 2 / 10 km | 1310 single λ | Cl. 140 (802.3cu) |
| 100GBASE-LR4 | 10 km | LAN-WDM | Cl. 88 |
| 100GBASE-ER4 / ER4-lite (vendor) | 40 km / 25–30 km | LAN-WDM | Cl. 88 / vendor (ER4-lite without SOA, FEC assumed) |
| 100GBASE-ZR | 80–120 km | C-band coherent | Cl. 154 (802.3ct) |
| 200GBASE-DR4 / FR4 / LR4 / ER4 | 500 m / 2 / 10 / 40 km | 1310 ×4 / LAN-WDM | Cl. 121, 122 |
| 400GBASE-DR4 | 500 m | 1310 × 4 fibres (MPO-12) | Cl. 124 |
| 400GBASE-FR4 / LR4-6 | 2 km / 6 km | CWDM 4 λ | Cl. 151 (802.3cu) |
| 400G-LR4-10 (100G Lambda MSA) | 10 km | CWDM 4 λ | MSA |
| 400GBASE-FR8 / LR8 / ER8 | 2 / 10 / 40 km | LAN-WDM 8 λ | Cl. 122 (ER8: 802.3cn) |
| 400GBASE-ZR / OpenZR+ | 80–120 km / up to ~400 km+ amplified | C-band coherent | Cl. 156 (802.3cw) / MSA |
| 800G-DR8 / DR8-2 | 500 m / 2 km | 1310 × 8 fibres | 802.3df |
| 800G 2×FR4 / 2×LR4 (MSA) | 2 / 10 km | CWDM 4 λ × 2 | dual LC / CS |
| 800G-ZR / ZR+ | 80–120 km / longer amplified | coherent | OIF 800ZR / OpenZR+ |
| 1.6TBASE-DR8 / DR8-2 | 500 m / 2 km | 1310 × 8 fibres | 802.3dj (in progress) |
Wavelength plans: Wavelength bands; full PMD list: PMD reference.
Copper and active cables (typical products)
| Rate | Passive DAC | Active (ACC / AEC) | AOC | Notes |
|---|---|---|---|---|
| 10G SFP+ | 1–7 m (10 m thin AWG) | up to 15 m active | 1–100 m (300 m OM3 vendor) | 10GBASE-CR / SFF-8431 |
| 25G SFP28 | 1–3 m (5 m with RS-FEC, CA-L) | up to 7 m | 1–100 m | CA-N/CA-S/CA-L cable classes |
| 40G QSFP+ | 1–5 m (7 m) | up to 10 m | 1–100 m | 40GBASE-CR4 |
| 100G QSFP28 | 1–3 m (5 m 26 AWG) | up to 7 m AEC | 1–100 m | 100GBASE-CR4 |
| 200G QSFP56 | 1–3 m | up to 5–7 m | 1–100 m | 200GBASE-CR4 |
| 400G QSFP-DD / OSFP | 1–2.5 m (3 m) | AEC 3–7 m | 1–100 m | 400GBASE-CR8 |
| 800G OSFP / QSFP-DD800 | 1–2 m | AEC 2–5 m | 1–50 (100) m | 800GBASE-CR8 |
| 1.6T (200G/lane) | ≤ 1 m | AEC ≤ 3 m | — | 802.3dj |
Passive reach shrinks with each doubling of lane rate; AEC restores 5–7 m at the cost of power (DAC vs AOC, Cable internals).
Fibre Channel
| Speed | OM2 | OM3 | OM4 / OM5 | LW (SMF) | Standard |
|---|---|---|---|---|---|
| 4GFC | 150 m | 380 m | 400 m | 10 km (4 km some) | FC-PI-2 |
| 8GFC | 50 m | 150 m | 190 m | 10 km | FC-PI-4 |
| 16GFC | 35 m | 100 m | 125 m | 10 km (ELW 25 km) | FC-PI-5 |
| 32GFC | 20 m | 70 m | 100 m | 10 km (ELW 25 km) | FC-PI-6 |
| 64GFC | — | 70 m | 100 m | 10 km | FC-PI-7 |
| 128GFC (4 × 32G, MPO) | — | 70 m | 100 m | — | FC-PI-6P |
FC optics are speed-negotiated over three generations; reach is quoted at the top speed (FC optics).
InfiniBand (typical LinkX-class portfolios)
| Generation | Passive DAC | AOC | Optics MMF | Optics SMF |
|---|---|---|---|---|
| FDR (56G) | 3–4 m | up to 100 m | SR4 100 m OM3 | — |
| EDR (100G) | 2–3 m (5 m) | 3–100 m | SR4 100 m OM4 | LR4 10 km (rare) |
| HDR (200G) | 1–2 m (3 m) | 3–100 m | SR4 100 m | DR4 500 m, FR4 2 km |
| NDR (400G, twin-port OSFP 2×400G) | 1–2 m; ACC 3 m | 3–50 m (100 m) | SR4 50 m / 100 m | DR4 500 m, FR4 2 km |
| XDR (800G) | ≤ 1.5 m; ACC/AEC 3 m | 3–50 m | SR8 50 m | DR8 500 m |
Fabric vendors validate cable identity and length (IB cables).
PON (budget classes, not fixed distance)
| System | Class | Loss budget | Typical distance |
|---|---|---|---|
| GPON | B+ / C+ | 28 / 32 dB | 20 km (60 km logical) |
| XG-PON / XGS-PON | N1 / N2 / E1 / E2 | 29 / 31 / 33 / 35 dB | 20 km, 40 km differential |
| EPON / 10G-EPON | PX20 / PR30 | 24 / 29 dB | 20 km |
| 50G-PON | N1 / N2 / E1 / E2 | 29 / 31 / 33 / 35 dB | 20 km |
The split ratio eats the budget: a 1:32 splitter costs ~17.5 dB, 1:64 ~21 dB (ODN classes & budget).
Reading the numbers
- Standard reach assumes worst-case fibre attenuation and modal bandwidth, a full connector allowance (typically 1.5 dB for MMF SR links) and end-of-life Tx power.
- Vendor reach ("300 m on OM3" for a 10G SR) may assume better fibre or less connector loss; check the datasheet's conditions (Reading a datasheet).
- Longer than needed is fine on MMF; on SMF a 40/80 km module on a 2 km link may overload the receiver — attenuate (Rx power & link budget).
- Mixing OM types, or SR and LR ends, does not work (Physical mismatches).
- Budget arithmetic and per-item losses: Units & conversions.
In CodingBox
The module's own reach claim is stored in the length bytes (SMF km, OM1–OM4 units) and its PMD in the compliance codes; CodingBox shows both, so a "10 km LR" label on a module whose EEPROM says 300 m OM3 is caught before it is racked (Check transceiver, Memory map).