Not just the number. The weight that moves you a category, and how close you are.
BMI is a blunt instrument, and it knows nothing about you. It's height and weight. That's the whole formula. It can't tell muscle from fat, so it calls plenty of athletes obese; it doesn't see where you carry weight, which is the part that actually matters for health; and it behaves differently across ages and ethnicities. It's a rough population screen, useful mostly for watching your own number move. It is not a diagnosis and not medical advice.
Tirzing tracks your BMI off every weigh-in, alongside body measurements, which catch what BMI can't: the weeks the scale sits still and your waist doesn't.