There are a number of methods of estimating bodyfat percentage ranging from lo-tech to high-tech and accurate to horribly inaccurate. Which you use depends on your goals and what you have access to. I won’t bore you listing all of them, rather I’ll focus on which ones I think are worth pursuing in this specific case.
According to the information presented in the book A Guide to Flexible Dieting by Lyle McDonald, relatively lean individuals, athletes or bodybuilders, should either know what their bodyfat percentage is or have some reasonable method of estimating it. Calipers would be one of preferred method.
Another possible method, although fraught with potential problems are the bioelectrical impedance bodyfat scales . The problem is that these devices are drastically affected by hydration, a large glass of water or a big piss can alter the number. But it is doubtful they are that accurate but assuming you control for hydration, they can at least give you a starting point and some ability to track relative changes. If you’re not that lean and not currently very active, there’s a fairly easy way to get a rough estimate of your bodyfat percentage and that is by using something called the Body Mass Index (BMI). BMI is supposed to be a measure of fatness but it’s really not, what it does is relate height and weight with certain BMI ranges (supposedly) being associated with health or not. The problem with BMI is that it doesn’t factor bodyfat percentage into account.
For example we have two individuals who are 6 feet tall and weigh 200 lbs.. But say one is an athlete and has 10% bodyfat and the other is not and has 30% bodyfat. They will have the same BMI value but it’s fairly clear (it should be anyhow) that they are not going to be in the same boat in terms of health risk or anything else. Basically, BMI makes no distinction between fat mass and LBM and since active individuals typically have more LBM (and hence less fat) at any given bodyweight, BMI is not accurate for them.However, recent research allows us to use BMI to get a rough idea of bodyfat percentage.