How do you determine or calculate ground lease monthly payments?

You would calculate it like any other form of commercial lease rates: by taking the value of the asset and multiplying it by an appropriate cap rate or yield. This would give you the annual net lease rate (ie. taxes and other operating costs in addition to this amount). As an example, if the land was improved with completed site work and asphalt and that value for the land equated to $1,000,000 per acre, you then take a market capitalization rate (say 8%) and apply it to the land value. The result is an annual net lease payment of $80,000 per acre.

Take the land value and multiply that number by a fair cap rate. Divide that number by 12, for a monthly payment.
I hope that this helps!
Francis Lennarz
RE/MAX of Valencia Commercial
1.661.406-4682
lennarzrealestate@gmail.com

Follow-up from my previous answer...
The payment would be NNN. The tenant would absorb the taxes, etc.

In an absolute NNN lease situation - take the value of the land and divide by 10 years and then by 12 months and there is an indication of the ground lease amount.