BIK on LCV's including private use

Can you guys please clarify what the BIK costs are for a company van/pickup, based on including private use? I've had a look online and I'm getting conflicting information, some which say if the van is occasionally used for private use or contributions are paid towards the vehicle. So confused.

All I am after is simply the monthly BIK including private use. I think it's £3,170 divided by 12 months or is it 20% of £3,170 divided by 12 (based on being a 20% tax payer)? Or something completely different.

Cheers.