Sometimes on screen we see 2 or 3 horses's prices either become Equal Favorites or close to being equal. They may jump around a bit one surpassing the other or what not.

Question is, how far apart number wise would be a general rule of thumb where it's EF or just off an EF race ?

For example, if Horse 1 is showing 2.50 and Horse 2 is showing 2.80,
that's 30 cents apart. One can assume they are "Equal Favorites"
At what point can it not be regarded as EF's ?
It can show sometimes to be the 3.80.s and 4.10's

Percentages would be fine to if anyone uses percentages rather than plain numbers.

Thanks