This is another question that we are frequently asked. We have had various tests done on the effectiveness of our Himalayan Salt Lamps to generate negative ions, and have developed the following general guidelines. Please note that different companies refer to the sizes of the Himalayan Salt Lamps by various names, so it is important to compare by weight and height, not just name. At Himalayan Salt Cart our lamps are categorized as follows: 

<< NAME >>      <<  HEIGHT  >>    <<  WEIGHT  >>     <<  PROTECTION RADIUS  >>

Mini Lamps               4 - 5 Inches               3 - 5 Pounds                 8 X 8 SQUARE FEET

Small Lamps              5 - 7 Inches               6 - 8 Pounds               10  X 10 SQUARE FEET

Medium Lamps         7 - 9 Inches               9 - 11 Pounds             12  X 12 SQUARE FEET

Large Lamps             9 - 11 Inches            12 - 15 Pounds             14  X 14 SQUARE FEET

Extra Large Lamps   10 - 12 Inches           16 - 20 Pounds             15  X 15 SQUARE FEET

Jumbo Lamps          11 - 13 Inches           21 - 25 Pounds             16  X 16 SQUARE FEET

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