Packet Rate Calculator
Calculate packets-per-second rate and its CPU load impact on network interrupt handling.
About Packet Rate Calculator
Line-rate packets-per-second isn't simply bandwidth divided by frame payload size — the wire-level cost of every Ethernet frame also includes a fixed preamble/SFD (used for clock synchronization) and a mandatory interframe gap (idle time between frames), both of which consume link time without carrying data. Dividing total link bandwidth by the sum of frame size, preamble, and IFG (all converted to bits) gives the maximum achievable packet rate — this is why small packets achieve far lower throughput efficiency than large ones: the fixed overhead is amortized over less payload.
Formula
Packets per second
pps = bandwidth_bps / (frame_size_bits + IFG_bits + preamble_bits)
- B
- bandwidth in bits/sec
- L_{frame}
- frame size in bits
- G_{ifg}
- interframe gap in bits
- L_{pre}
- preamble + SFD in bits
Worked example
With the default values below, Packet Rate Calculator returns Packet Rate (packets/sec) of 81,274.4. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Bandwidth (Mbps)minimum 0.1
- 1,000
- Frame Size, Excl. Preamble/IFG (bytes)accepts 64–9,018
- 1,518
- Interframe Gap (bits)minimum 0
- 96
- Preamble + SFD (bits)minimum 0
- 64
Results
- Packet Rate (packets/sec)
- 81,274.4
- Packet Rate (Mpps)
- 0.0813
- Total Bits per Frame (incl. IFG + preamble)
- 12,304
Step by step
- 1Values used
- 2Packets per second
- 3Packet Rate (packets/sec)= 81,274.4
- 4Packet Rate (Mpps)= 0.0813
- 5Total Bits per Frame (incl. IFG + preamble)= 12,304
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 or compounding frequency into account.
- Figures are rounded for display to 4 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
Why is minimum-size-frame PPS the key metric for network hardware specs?
Vendors quote 'line-rate' or 'wire-speed' PPS using the smallest legal Ethernet frame (64-byte payload, 84 bytes on the wire with overhead) because that's the worst case for a switch/router's per-packet processing budget — a device rated for line-rate at 64 bytes can handle any larger, less demanding frame size at full bandwidth too.
How do I measure actual packet rate on a Linux interface?
`sar -n DEV 1` reports rxpck/s and txpck/s per interface per second; `ethtool -S <iface>` on supported NICs exposes hardware packet counters that can be sampled and diffed for precise rate calculation.
Does jumbo frame usage change the packet rate for the same bandwidth?
Yes — larger frames (e.g. 9000-byte jumbo frames) amortize the fixed preamble/IFG overhead over more payload bytes, reducing the packets-per-second needed to sustain the same throughput and lowering per-packet CPU/interrupt overhead, at the cost of requiring jumbo-frame support across the entire path.