PCIe Bandwidth Calculator
Choose a PCIe generation and lane count to see the link bandwidth, or enter a target to see how many lanes it needs.
Figures are theoretical link bandwidth after line encoding, before packet and protocol overhead, so real throughput is lower. Gen 6 and Gen 7 values are the headline rates (GT/s divided by 8). Estimates for general planning purposes — always verify against the PCI-SIG specification and your device and connector manufacturers' data.
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How This Is Calculated
Each PCIe lane runs at a raw rate in gigatransfers per second (GT/s). Bandwidth per lane is that rate, multiplied by the encoding efficiency of the generation, divided by 8 bits per byte:
Bandwidth per direction = (GT/s × efficiency ÷ 8) × lanes
Gen 1 and Gen 2 use 8b/10b encoding (80% efficient). Gen 3, Gen 4 and Gen 5 use 128b/130b encoding (about 98.5% efficient). Gen 6 and Gen 7 use PAM4 signaling with flit-based transfer, and this tool shows their headline rates (GT/s divided by 8) without subtracting flit or protocol overhead.
These are theoretical link figures. Real throughput is lower because of packet headers and other protocol overhead. For how the connector side changes between generations, see PCIe Connector Evolution: Gen 5 and Gen 6 and the Gen 5 vs Gen 6 vs Gen 7 connector comparison.