Just to extend that . . . it's not possible -- with ANY acid or base -- to calculate the exact pH rise from a given addition of acid or base, without DETAILED and ACCURATE knowledge of the pool's water chemistry. Many pool dealer test computers are more than 'detailed' enough, giving answers like 161 ppm hardness . . . but they are not nearly accurate enough. We've several times had neighbors go into pool stores carrying water samples that were all from the same pool, and get wildly different results from the super-detailed, but super-inaccurate pool dealer test computer!

You have to remember: pool stores make more if your pool water is messed up!

Anyhow, you can use an acid/base demand kit to determine the pH increase or decrease if you use a strong* acid or base (like muriatic acid or caustic soda) but once you start using weak* acids (like boric acid or) bases (like borax) the situation becomes more complicated.

That is why it's better to add a reasonable dose, check the pH, and add more if needed.

* In this case, "strong" or "weak" are chemical technical terms with very specific meanings.