Frame Size Calculator
Calculate total Ethernet frame size including headers, payload and trailer.
About Frame Size Calculator
The total Ethernet frame size on the wire is the payload plus a 14-byte header (destination/source MAC and EtherType) and a 4-byte Frame Check Sequence; a tagged trunk frame adds a further 4-byte 802.1Q VLAN tag between the source MAC and EtherType fields. Ethernet also enforces a 64-byte minimum frame size, so undersized payloads are padded up to that floor, and any frame exceeding 1518 bytes (1522 with a VLAN tag) is considered oversized unless the network explicitly supports jumbo frames.
Formula
Total frame size
total = payload + ethernet_header(14) + FCS(4) [+ VLAN_tag(4) if tagged]
- P
- Payload size in bytes
- \mathbb{1}_{VLAN}
- 1 if 802.1Q tagged, else 0
Worked example
With the default values below, Frame Size Calculator returns Total Frame Size on Wire of 1,478. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Payload Sizeaccepts 0–9,000 bytes
- 1,460 bytes
- 802.1Q VLAN Tagged
- No
Results
- Total Frame Size on Wire
- 1,478 bytes
- VLAN Tag Added
- 0 bytes
- Minimum-Size Padding Added
- 0 bytes
- Exceeds Standard 1518/1522-byte Frame?
- No — fits standard Ethernet
Step by step
- 1Values used
- 2Total frame size
- 3Total Frame Size on Wire= 1,478 bytes
- 4VLAN Tag Added= 0 bytes
- 5Minimum-Size Padding Added= 0 bytes
- 6Exceeds Standard 1518/1522-byte Frame?= No — fits standard Ethernet
Assumptions and limits
- The result is derived only from the 2 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 whole numbers, 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
What is the maximum standard Ethernet frame size?
The standard maximum is 1518 bytes total (1500-byte MTU payload + 14-byte header + 4-byte FCS). An 802.1Q VLAN-tagged frame adds 4 more bytes, raising the tagged maximum to 1522 bytes. Anything larger requires jumbo frame support end-to-end.
Why is there a 64-byte minimum Ethernet frame size?
The minimum frame size exists so that, historically on shared half-duplex Ethernet (CSMA/CD), a transmitting station could reliably detect a collision before finishing sending a frame — a frame shorter than the round-trip propagation delay of the segment could complete transmission before a collision was noticed. Modern full-duplex switched networks don't need this for collision detection, but the minimum remains part of the standard, and undersized frames are padded to meet it.
How much extra overhead does VLAN tagging add per frame?
An 802.1Q tag adds exactly 4 bytes to every frame that carries it (2 bytes Tag Protocol Identifier + 2 bytes Tag Control Information containing the VLAN ID and priority bits), which is why the maximum tagged frame size is 1522 rather than 1518 bytes.