The scales don't tell you the whole picture - your weight is less important than your percentage of body fat when it comes to appearance, fitness, and health. Tracking your percentage of body fat better shows how you are doing with diet and exercise than measuring weight.
Home Body Fat Monitors
To take your body fat percentage yourself at home, you can use one of the bioelectrical impedance devices for a measurement that is about as consistent and accurate as hydrostatic weighing, and as easy to use as your bathroom scale - in fact many models ARE bathroom scales. Or you can learn to use body fat calipers, which can be trickier to get a consistent reading.
Bioelectrical Impedance Analysis (BIA)
With this method, a device sends a tiny electrical charge through your hands or feet and uses the data to determine how much of you is fat and how much of you is water, with muscles and lean tissues being mostly water. To do the calculation, the unit needs to know your gender, age, and weight. These units should not be used by anybody with a pacemaker, but should be safe for most others.
Features of BIA Fat Monitors
Look for memory features so don't have to put in your basic data each time, and if others will use it get a unit that remembers multiple users. If you are an athlete of low body fat/high muscle mass you should get a unit with an athlete setting to get more accurate measurement. If you have a child to measure, get a unit with a child setting. A unit that acts as a scale is also convenient.
Getting Accurate Readings with BIA Monitors
You must not be dehydrated - do not use first thing in the morning or immediately after a workout or after consuming alcohol. Use 3 hours after a meal and after voiding your bladder. Women may experience fluctuations with retaining water, and those on diuretics may see inaccurate readings. You need to weigh yourself without clothes.
Skinfold Caliper Method
With the caliper method, you take pinches of your skin at three points on your body and calculate the fat percentage from those readings. New electronic calipers sense the right pressure and do the calculations for you, plus store data for multiple users.