Optical layer

400G vs 800G Economics

Per-Gbps cost, power, and rack-density tradeoff for 400G vs 800G fabric in mid-2026.

The engineer question
Is 800G cheaper per Gbps than 400G right now?

Where the data lives today

The current quarter snapshot is generated by the V17 Phase D Product Landscape module and lives on the parent topic page. The interactive comparator below ships once a structured spec datasource is wired.

View Optical product landscape →

Inputs

Count of full duplex modules in the deployment.

Result

$ / Gbps — 400G
$1.50
$ / Gbps — 800G2% cheaper per Gbps
$1.46
W / Gbps — 400G
27.5 mW/Gbps
W / Gbps — 800G
20.0 mW/Gbps
Total module spend — 400G
$598.0 k
Total module spend — 800G
$1.17 M
Rack density delta800G halves the switch-port count for the same fabric bandwidth
+100%

Recommendation

800G is ~2% cheaper per Gbps but the margin is small — switch-silicon refresh cost dominates the decision. If you're locked into 12.8/25.6 Tbps switches for the next 12 months, stay on 400G.

Assumptions

  • · Reach: DR4 (single-mode, ≤ 500 m). Mid-2026 hyperscaler module ASP. Spot-market prices on alibaba/fibermall are 30–60% higher for sub-1k volume.
  • · 400G module price today: $650; 800G module price today: $1500
  • · Horizon adjustment: +12 months — 400G drops 8% (mature curve), 800G drops 22% (ramping)
  • · Power: 11 W (400G), 16 W (800G). LPO/CPO can shave 20–30% off these but adds vendor lock-in.
  • · Excluded: switch silicon refresh cost (typically $50–150k/switch), DSP/CDR refresh, optics-to-fibre breakout cassettes, ZR coherent for > 10 km reach
  • · Excluded: supplier reliability dimension (Coherent / Lumentum / Innolight / Eoptolink) — see /tools/optical/coherent-vs-lumentum-comparison

Worked example (default inputs)

Result

$ / Gbps — 400G
$1.50
$ / Gbps — 800G2% cheaper per Gbps
$1.46
W / Gbps — 400G
27.5 mW/Gbps
W / Gbps — 800G
20.0 mW/Gbps
Total module spend — 400G
$598.0 k
Total module spend — 800G
$1.17 M
Rack density delta800G halves the switch-port count for the same fabric bandwidth
+100%

Recommendation

800G is ~2% cheaper per Gbps but the margin is small — switch-silicon refresh cost dominates the decision. If you're locked into 12.8/25.6 Tbps switches for the next 12 months, stay on 400G.

Assumptions

  • · Reach: DR4 (single-mode, ≤ 500 m). Mid-2026 hyperscaler module ASP. Spot-market prices on alibaba/fibermall are 30–60% higher for sub-1k volume.
  • · 400G module price today: $650; 800G module price today: $1500
  • · Horizon adjustment: +12 months — 400G drops 8% (mature curve), 800G drops 22% (ramping)
  • · Power: 11 W (400G), 16 W (800G). LPO/CPO can shave 20–30% off these but adds vendor lock-in.
  • · Excluded: switch silicon refresh cost (typically $50–150k/switch), DSP/CDR refresh, optics-to-fibre breakout cassettes, ZR coherent for > 10 km reach
  • · Excluded: supplier reliability dimension (Coherent / Lumentum / Innolight / Eoptolink) — see /tools/optical/coherent-vs-lumentum-comparison

Related tools in the Optical layer

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