Work out bitstream size instantly with clear inputs, formula shown and shareable results.
Bitstream size is logic cells times configuration bits per cell — roughly 100-150 bits each once routing, LUT contents and BRAM initialisation are counted. Configuration time is the compressed size divided by the load interface speed, which is why boot time drives the choice of x8 or x16 flash.
Bitstream
bits = cells x config bits per cell; config time = compressed bits / interface speed
Most bits configure routing, not logic. Interconnect multiplexers vastly outnumber LUT configuration bits.
Wider and faster flash interfaces, bitstream compression, and partial reconfiguration where only the changed region is loaded.