A waist measurement is the cheapest and simplest way other than just looking.

You want to make sure you measure under similar conditions, like in the morning after relieving yourself (for example).

If it's too high, losing a ~0.5-1 lbs per week while strength and endurance training with progressive overload will get it down sustainably.

https://www.barbellmedicine.com/blog/visceral-fat-waist-vs-w...