NIC Throughput Calculator
Compare a NIC's line-rate packet ceiling against what its CPU cores can actually process.
About NIC Throughput Calculator
The link imposes one packet ceiling and the host's packet-processing path imposes another; the achievable rate is the lower of the two, converted back into bits per second. Segmentation and receive-side offloads raise the CPU ceiling by batching per-packet work. A 25 or 100 Gbit/s NIC in a box with too few cores or offloads disabled delivers a fraction of its rating, and the symptom looks like a network fault rather than a host limit.
Formula
NIC Throughput
line-rate pps = link bits/s ÷ ((frame + 20) × 8); achievable pps = min(line rate, cores × pps per core × offload factor).
- frame + 20
- Frame plus preamble and interframe gap
- pps per core
- Packets a single core can process per second
- offload factor
- Uplift from TSO, LRO and RSS (≈1.8×)
Worked example
With the default values below, NIC Throughput Calculator returns Achievable Throughput of 10.00. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Link speedminimum 0.001 Gbit/s
- 10 Gbit/s
- Average frame sizeaccepts 64–9,022 bytes
- 1,518 bytes
- Cores handling packetsminimum 1 cores
- 4 cores
- Packets per second per coreminimum 1,000 pps
- 1,400,000 pps
- Hardware offload enabled (TSO/LRO/RSS)
- Yes
Results
- Achievable Throughput
- 10.00 Gbit/s
- Line-Rate Packet Ceiling
- 812,744 pps
- CPU Packet Ceiling
- 10,080,000 pps
- Achievable Packet Rate
- 812,744 pps
- Binding Constraint
- Link line rate
Step by step
- 1Values used
- 2NIC Throughput
- 3Achievable Throughput= 10.00 Gbit/s
- 4Line-Rate Packet Ceiling= 812,744 pps
- 5CPU Packet Ceiling= 10,080,000 pps
- 6Achievable Packet Rate= 812,744 pps
- 7Binding Constraint= Link line rate
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, 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 NIC Throughput calculated?
line-rate pps = link bits/s ÷ ((frame + 20) × 8); achievable pps = min(line rate, cores × pps per core × offload factor). The link imposes one packet ceiling and the host's packet-processing path imposes another; the achievable rate is the lower of the two, converted back into bits per second. Segmentation and receive-side offloads raise the CPU ceiling by batching per-packet work.
Why does NIC Throughput matter?
A 25 or 100 Gbit/s NIC in a box with too few cores or offloads disabled delivers a fraction of its rating, and the symptom looks like a network fault rather than a host limit.
What values do I need to enter?
This calculator takes 5 inputs: Link speed, Average frame size, Cores handling packets, Packets per second per core, Hardware offload enabled (TSO/LRO/RSS). The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.