40G to 100G Migration Calculator
Plan a 40G to 100G migration: ports needed, capacity gain and access ports gained through 4×25G breakout.
Inputs
100G Ports Required
24ports
Capacity after Migration
2,400Gbps
Projected Demand
2,329.6Gbps
Switch Ports Freed
40ports
Capacity Gain per Port
150%
Access Ports Presented
96ports
Step by step
Values used
40G ports in service = 64 ports; Average utilisation today = 65 %; Growth over the planning horizon = 40 %; Use 100G to 4×25G breakout for access = Yes
40G to 100G Migration
projected demand = 40G ports × 40 × utilisation × (1 + growth); 100G ports = ceil(demand ÷ 100); each port carries 2.5× more, so the gain per port is 150%.
100G Ports Required
= 24 ports
Capacity after Migration
= 2,400 Gbps
Projected Demand
= 2,329.6 Gbps
Switch Ports Freed
= 40 ports
Capacity Gain per Port
= 150
Access Ports Presented
= 96 ports
How it works
The migration is sized on projected demand rather than a port-for-port swap, because each 100G port carries two and a half times the traffic of a 40G port and therefore fewer ports are needed. Where the workload is 10G or 25G servers, breakout turns each 100G port into four access ports and avoids buying separate access switches. 40G uses four 10G lanes and is a technological dead end; 25G-based 100G is cheaper per gigabit and is the step that unlocks 400G later on the same fibre.
Formula
40G to 100G Migration
projected demand = 40G ports × 40 × utilisation × (1 + growth); 100G ports = ceil(demand ÷ 100); each port carries 2.5× more, so the gain per port is 150%.
- breakout
- A 100G QSFP28 port split into four independent 25G lanes
- gain per port
- 100G against the 40G it replaces — 150% more capacity on the same cage
Frequently Asked Questions
How is 40G to 100G Migration calculated?
projected demand = 40G ports × 40 × utilisation × (1 + growth); 100G ports = ceil(demand ÷ 100); each port carries 2.5× more, so the gain per port is 150%. The migration is sized on projected demand rather than a port-for-port swap, because each 100G port carries two and a half times the traffic of a 40G port and therefore fewer ports are needed. Where the workload is 10G or 25G servers, breakout turns each 100G port into four access ports and avoids buying separate access switches.
Why does 40G to 100G Migration matter?
40G uses four 10G lanes and is a technological dead end; 25G-based 100G is cheaper per gigabit and is the step that unlocks 400G later on the same fibre.
What values do I need to enter?
This calculator takes 4 inputs: 40G ports in service, Average utilisation today, Growth over the planning horizon, Use 100G to 4×25G breakout for access. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.