There is no such globally accepted formula. Time controls are defined only by their formal definitions (as unhelpful as that sounds). Any further descriptive language, like "blitz" or "lightning" or "bullet", while they carry certain conventional connotations, do not have objective criteria. However, certain organizations may define these terms concretely within their own domains.
USCF
The USCF defines three time-control zones: Regular, Quick, and Blitz. Different sets of time controls fall into one (or more--it is possible for a game to count as both Regular and Quick, in which case the player's ratings in both categories are affected) of these categories. Determining the category is simple: calculate the [estimated] total playing time (TPT_U
) as:
TPT_U = Minutes + SecondsPerIncrement
The TPT_U
is then slotted into a zone as follows:
TPT_U > 65: Regular
30 ≤ TPT_U ≤ 65: Regular AND Quick
10 < TPT_U < 30: Quick
5 ≤ TPT_U ≤ 10: Blitz
FIDE
FIDE defines (as far as I can tell) two time-control zones beyond the standard FIDE time control: Rapid and Blitz. To determine which of these zones a time control falls within, calculate the [estimated] total playing time (TPT_F
) as:
TPT_F = Minutes + SecondsPerIncrement
The TPT_F
is then slotted into a zone as follows:
10 < TPT_F < 60: Rapid
TPT_F ≤ 10: Blitz
CHESS.COM
Chess.com defines three time-control zones: Standard, Blitz, and Bullet. To determine which of these zones a time control falls within, calculate the [estimated] total playing time in minutes (TPT_C
) as:
TPT_C = Minutes + 2/3*SecondsPerIncrement
This assumes a forty-move game and is derived from the following expression (multiply the increment in seconds by forty, then convert to minutes):
TPT_C = Minutes + (40 * SecondsPerIncrement / 60)
The TPT_C
is then slotted into a zone as follows*:
15 ≤ TPT_C: Standard
3 ≤ TPT_C < 15: Blitz
TPT_C < 3: Bullet
*I've had to extrapolate here, as the definition actually appears to leave a gap between 14 and 15 minutes. I've filled this gap in the manner I considered most likely to be accurate.
Examples
Base | Incr | TPT_U | TPT_F | TPT_C | USCF | FIDE | CHESS.COM
-----|------|-------|-------|-------|-------|-------|----------
2 | 1 | 3 | 3 | 2.667 | N/A | Blitz | Bullet
3 | 0 | 3 | 3 | 3 | N/A | Blitz | Blitz
3 | 2 | 5 | 5 | 4.333 | Blitz | Blitz | Blitz
5 | 0 | 5 | 5 | 5 | Blitz | Blitz | Blitz
10 | 0 | 10 | 10 | 10 | Blitz | Blitz | Blitz
10 | 1 | 11 | 11 | 10.67 | Quick | Rapid | Blitz
14 | 3 | 17 | 17 | 16 | Quick | Rapid | Standard