Non-Witness:
Outpoint size = 32+4 Sequence size = 4 ScriptSig VarInt Size= 1
Witness:
WitScript VarInt Size= 1 Then script itself: 65 signature size + 1 byte of push opcode
(32 + 4 + 4 + 1) + (65+1+1)/4=57.75, rounded up 58.
We assume 65 of signature size rather than 64, since we can't assume the sighash to be Default.