I know it is an algorithm owned by Majestic, however is there a rough calculation formula? For example, let's assume we register a new domain with no backliks and than add 10 dofollow backlinks, each from domain of TF=20. What TF will my domain get? A couple of years ago when google page rank mattered, there were formulas to calculate PR.
Trust Flow is calculated using a (secret) set of highly authoritative seed websites as a baseline. The further away your domain is from these seed sites, the lower your domain's trust flow will be. The seed set of authority sites link out to other good sites, and those sites link out to more good sites, etc. The closer your domain is to these seed sites, via inbound links, the higher your Trust Flow score will be.
I prefer to think of it this way; Trust Flow measures the quality of your inbound links based on the quality of the inbound links pointing to the site that your inbound links come from. To simplify it further, if all of your inbound links come from sites with high trust flow, then your domain will also have a high trust flow. That's because the sites that your links come from also have great inbound links going to them.
Trust flow is quite a difficult metric to manipulate, and topical trust flow is virtually impossible to manipulate and inflate.