The accuracy of consumer weight scales varies widely, which makes it challenging to track your progress. This is especially true if you're on a targeted weight loss plan, or you are an athlete in a sport such as wrestling or boxing, where you must reach a certain weight to participate. It's necessary to find the most accurate bathroom scale that meets your needs. Analog scales -- the ones with the wobbly dials -- aren't very accurate, so you should avoid them when you need a precise measurement.
Most Accurate for Measuring Body Fat
Weighing underwater has long been regarded as the gold standard for assessing body fat percentages. The margin of error is approximately plus or minus 1.5 percent, according to Georgia State University's Department of Kinesiology and Health. Underwater systems are based on the principle that lean tissue is heavier than fat; therefore, fat is expected to float in water, while lean tissue will sink.
A professional assesses your dry weight out of water versus your weight submerged underwater to accurately determine your body fat percentage. This is a good option if, for instance, you are a bodybuilder and want to accurately track your body fat and lean mass. Due to the nature of this type of scale setup, you'll need to see a sports medicine professional to have this method of weighing performed.
Most Accurate Digital Scales
In digital scales, the accuracy varies widely; watchdog website Consumer Search conducted a review and rounded up the top three most accurate, best overall digital scales. Ranging in price from $36 to $65, the top picks are the EatSmart Precision Plus Digital Bathroom Scale, the Taylor 7506 Glass and Chrome Digital Scale and the Tanita HD-357 Digital Weight Scale with Handle. The Good Housekeeping Institute agreed that the Tanita HD was excellent, but chose a different model -- the Tanita HD-384 -- as the best overall digital scale after testing 30 models.
Most Accurate Smart Scale
The era of technology has ushered in smart scales to replace simple bathroom scales. This new breed of scales tracks all manners of your health, such as BMI and body fat, with sophisticated graphs and charts that wirelessly sync to your cellphone. However, smart scales come with a steeper price tag, so you'll want to make sure yours is accurate. Tech and science publisher LiveScience tested nine smart scales, including the Withings Smart Body Analyzer and the Fitbit Aria. After hands-on testing and analysis, LiveScience declared the Withings Smart Body Analyzer the most accurate and best overall smart scale.
Tips for Getting the Most Accuracy
Your weight varies depending on a number of variables, such as how much water you've had to drink, what time of day you weigh yourself, and what type of food you've eaten, as well as the amount of clothing or lack thereof you wear during the measurement. If you're tracking weight loss progress and want to get the most accurate results, in addition to having an accurate scale, weigh yourself at the same time of day and under the same conditions. For example, it's common to track weight measurement first thing in the morning upon waking, with no clothing on and before you've had anything to eat or drink.
Don't Forget to Calibrate Your Body Weight Scale
Many consumers are unaware that when you first set up your scale and whenever you move it to a new location, you need to calibrate it. Calibrating allows the scale to adjust to any environmental factors -- such as carpet or hardwood floor -- so that it reads accurately. Check your scale's manual for calibration instructions. The process varies depending on the model of scale you have, but typically involves locating the calibration mode or button and placing an object that you know the weight of, such as a 3-pound dumbbell, onto the scale. Most modern scales reset automatically once the calibration process is complete.