A team’s cap hit is calculated based on each day of the season (186 days). For every day a player is on the roster, the team’s cap hit is their full year cap hit divided by 186.  Once a player is on the roster, the calculations assume they will be on the roster for the remainder of year. Example: If a player with a $925K cap hit gets called up 86 days into the season (100 days remaining), on that day the team’s projected cap hit for the year goes up $497,312 ($925K/186)*100.

Cap space “accrues” over time.  A team with $500K cap room to start the year can add a player with a $1,000,000 Cap Hit halfway through season (Day 93). Due to the way the cap is calculated, a player worth $1M annually will only count for $500,000 in actual cap charge through the remainder of the year.