Whether a game is blitz or standard depends on a formula that takes into account both the Start time and the Increment (Inc) value to get a sense of the total time a game might last. Here is the formula:
BLITZ if_and_only_if (Start + Inc*2/3) < 15
STANDARD otherwise
The following table shows the slowest blitz and fastest standard time controls, the dividing line if you will between the two types of matches. [Thanks to schwartzeer for the calculations. :) ]
Slowest Blitz | Fastest Standard | ||
Mins | Incr | Mins | Incr |
1 | 20 | 1 | 21 |
2 | 19 | 2 | 20 |
3 | 17 | 3 | 18 |
4 | 16 | 4 | 17 |
5 | 14 | 5 | 15 |
6 | 13 | 6 | 14 |
7 | 11 | 7 | 12 |
8 | 10 | 8 | 11 |
9 | 8 | 9 | 9 |
10 | 7 | 10 | 8 |
11 | 5 | 11 | 6 |
12 | 4 | 12 | 5 |
13 | 2 | 13 | 3 |
14 | 1 | 14 | 2 |
15 | 0 |
As you can see, not every game with more minutes to start is Standard and not every game with few minutes to start is Blitz.
See also: match