100G to 400G Upgrade Calculator
Consolidate 100G ports into 400G: port count saved, capacity delivered and power per gigabit improvement.
Inputs
400G Ports Required
32ports
Capacity Delivered
12,800Gbps
Switch Ports Freed
96ports
Optical Power Saved
192.0W
Power per Gigabit after Upgrade
0.0300W/Gbps
Logical Ports after Breakout
128ports
Step by step
Values used
100G ports in service = 128 ports; 400G breakout mode = 4 × 100G; Power per 100G optic = 4.50 W; Power per 400G optic = 12 W
100G to 400G Upgrade
400G ports = ceil(100G ports ÷ 4) when each 400G port breaks out to 4 × 100G; power per gigabit = 400G optic power ÷ 400.
400G Ports Required
= 32 ports
Capacity Delivered
= 12,800 Gbps
Switch Ports Freed
= 96 ports
Optical Power Saved
= 192.0 W
Power per Gigabit after Upgrade
= 0.0300 W/Gbps
Logical Ports after Breakout
= 128 ports
How it works
A 400G port carries four 100G lanes, so four existing links collapse onto one port and one trunk. Because a 400G optic draws roughly 12 W against 4.5 W for 100G, the per-gigabit power falls by about a third even though each module draws more. Switch port count and optical power are the two limits in a modern spine rack, and 400G consolidation relieves both without new fibre if MPO-16 trunks are already in place.
Formula
100G to 400G Upgrade
400G ports = ceil(100G ports ÷ 4) when each 400G port breaks out to 4 × 100G; power per gigabit = 400G optic power ÷ 400.
- breakout
- 400G port split into 4 × 100G, 8 × 50G or 2 × 200G lanes
- power per gigabit
- Optical watts divided by delivered capacity — the figure that scales in a rack
Frequently Asked Questions
How is 100G to 400G Upgrade calculated?
400G ports = ceil(100G ports ÷ 4) when each 400G port breaks out to 4 × 100G; power per gigabit = 400G optic power ÷ 400. A 400G port carries four 100G lanes, so four existing links collapse onto one port and one trunk. Because a 400G optic draws roughly 12 W against 4.5 W for 100G, the per-gigabit power falls by about a third even though each module draws more.
Why does 100G to 400G Upgrade matter?
Switch port count and optical power are the two limits in a modern spine rack, and 400G consolidation relieves both without new fibre if MPO-16 trunks are already in place.
What values do I need to enter?
This calculator takes 4 inputs: 100G ports in service, 400G breakout mode, Power per 100G optic, Power per 400G optic. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.