Rate is a statistic found in Castlevania games that measures map completion. Starting from Castlevania: Symphony of the Night, each map would count as 100% toward the total, leading to many following games having a greater than 100% maximum map rate.
Game specific information
Aside from a percentage rate of map completion, this game also features a room count, which allows the players to determine the number of blocks they have explored in the game's dungeons. The first map of the game takes place on the "normal castle" and it's possible to obtain an approximate of 99% map rate here. All of the blocks counted in the room count for the normal castle are 942 rooms.
However, once Alucard is able to save Richter Belmont through the use of the Holy Glasses, the dark priest Shaft appears and reveals the Reverse Castle, thus being the game's second map (but with an inverted layout). Entering this castle extends the map rate beyond 100%, as it contains another 948 rooms.
The maximum map rate in Symphony of the Night is 200.6% by visiting all 1,890 rooms without glitching.
Portrait of Ruin has a total of 10 maps (9 portraits plus the castle), and every map, including its secret rooms, has a maximum completion rate of 100%. So, by completing all 10 maps individually, the combined maximum rate is 1,000%. Each map counts toward an equal fraction (among maps) of the total map completion rate, regardless on how many block units the map contains relative to other maps. For example, a single map block will count more in total completion on the relatively sparse City of Haze or 13th Street maps than on other larger maps with more blocks.
Having at least 888% total map rate allows the player to access the Nest of Evil secret area.
Order of Ecclesia features a separate map for each dungeon unlike one whole map for the whole game. Therefore, the various areas in this game have their own map rates, which is helpful for determining what area has been cleared from those that were not. The map rate also makes up a percentage of the game's total completion rate.