40G to 100G Migration Calculator
Plan a 40G to 100G migration: ports needed, capacity gain and access ports gained through 4×25G breakout.
About 40G to 100G Migration Calculator
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
Worked example
With the default values below, 40G to 100G Migration Calculator returns 100G Ports Required of 24. Change any input above and every figure here is recalculated in your browser.
Inputs used
- 40G ports in serviceaccepts 1–20,000 ports
- 64 ports
- Average utilisation todayaccepts 1–100 %
- 65 %
- Growth over the planning horizonaccepts 0–500 %
- 40 %
- Use 100G to 4×25G breakout for access
- Yes
Results
- 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
Step by step
- 1Values used
- 240G to 100G Migration
- 3100G Ports Required= 24 ports
- 4Capacity after Migration= 2,400 Gbps
- 5Projected Demand= 2,329.6 Gbps
- 6Switch Ports Freed= 40 ports
- 7Capacity Gain per Port= 150
- 8Access Ports Presented= 96 ports
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
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.