how to calculate body fat percentage

{"cid":"91170832","title":"Sports Center \/ Wellness Spa Body Fat Percentage Calculator Machine with Multi - Frequency","imgUrl":"https:\/\/img.chinax.com\/nimg\/19\/7d\/a7126826a4a53d9d4754a5f4916a-200x200-1.jpg","attrs":{"Price":"Negotiated","Brand Name":"Lumsail","Model Number":"BS-BCA3","Minimum Order Quantity":"1 Set","Delivery Time":"Within 3 working days after we received the payment","Certification":"CE","Place of Origin":"Shanghai, China","Payment Terms":"L\/C, T\/T, Western Union, MoneyGram","Supply Ability":"500 unit per month","Packaging Details":"Standard export packing","Measurement Method":"Direct Segmental Multi-frequency Bioelectrical Impedance Analysis Method(DSM-BIA)","Electrode":"Tetrapolar 8-Point Tactile Electrode System","Body composition calculation method":"No Empirical Estimation","Testing Frequency":"5, 50, 100, 250, 500 KHz","Resistance Scope":"100 ~ 1000\u2126","Measurement item":"Right arm, left arm, body, right leg, left leg","Analysis History Storage":"10000 (can export through USB port)","External Interface":"RS232, USB2.0 (Storage & Printer), Ethernet"}}

{"cid":"91206047","title":"Professional Powerful Body Fat Percentage Calculator Machine 53VA","imgUrl":"https:\/\/img.chinax.com\/nimg\/cf\/c4\/9068a3c466f750f4ee85ea909d70-200x200-1.jpg","attrs":{"Price":"Usd","Brand Name":"OEM","Model Number":"C27","Minimum Order Quantity":"1 Set","Certification":"CE","Place of Origin":"China","Payment Terms":"D\/A, D\/P, T\/T, Western Union, MoneyGram","Packaging Details":"1. Standard export cartons. 2. Marked \"Handle with care\". 3. We also can pack goods as your request.","Product name":"Body Composition Analyzer","Type":"Body Fat Analyzer,Professional powerful type","Warranty":"1 Year","Function":"Body Healthy Check,fat analysis\/weight control,Body composition analysis","Printer":"Micro+Color","Rated current":"<180\u03bcA","Color":"Black","Application":"nutrition center,etc.,Gym,Home use,Hosipital","Language":"Enlglish"}}

{"cid":"91202149","title":"BCA100 Body Composition Analyzer Machine 50kHz Fat Percentage Calculator Machine","imgUrl":"https:\/\/img.chinax.com\/nimg\/11\/01\/c3b08ee1da3fe9986c1686031fbf-200x200-1.jpg","attrs":{"Price":"1850-2300usd\/piece","Model Number":"Body Composition Analyzer-4","Minimum Order Quantity":"1","Delivery Time":"3-5days","Certification":"CE,FDA,ISO90","Place of Origin":"Beijing,China","Payment Terms":"L\/C, D\/A, D\/P, T\/T, Western Union, MoneyGram","Supply Ability":"1000 sets per week","Packaging Details":"118X55X40 cm","Name":"body composition analyzer","Type":"biochemical analysis system","Warranty":"1 Year","Color":"white","After-sale Service":"Online technical support","Technology":"BIA Technology","Input":"AC 100-240V, 50\/60HZ, 0.8-1.5A","Output":"DC 12V, 3A adaptor","Operation environment":"50-104\u00b0F(10-40\u00b0C), 30-75%RH, 70-106KPA","Storage environment":"4-158\u00b0F(-10-70\u00b0C), 10-80%RH, 50-106KPA"}}