Air Testing Your Metal Detector

Air Testing Your Metal Detector

Understanding generally what numbers appear for different detecting finds under ideal conditions is critical to mastering the operation of your detector. Sure you probably understand penny, nickel, dime, quarter etc. from your test garden. But what about a wider variety of targets that you stand a good chance of finding.

How are you going to decide whether or not to dig a $5 gold piece, for example, if you have no idea at what range it falls on your detector? Understanding which targets’ numbers fall in the same ranges as common trash is also important. As the saying goes: “You have to dig a lot of pull-tabs to dig gold rings.”

A good detectorist understands that the readings displayed on the detector are only one piece of information provided to assist you in evaluating a target to determine if you would like to dig. Other information includes, but is not limited to, signal repeatability, repeatability at different angles, and the characteristics of the target’s sound in your headphones.

You can consult the internet and detecting forums to locate numbers for different common finds for your detector, or you can test different objects yourself. Just pick a spot away from any metal or electrical interference. Laying the detector on the kitchen table works, but I prefer to put the objects on a piece of clear ground and pass the coil over them at about 4 inches, so I can see the display.

The following tests were performed on both the MineLab e-Trac and the Fisher F75 LTD. All targets were tested at about 4″ in open air. Keep in mind that the readings displayed on your detector can vary +/- about two points even under ideal conditions, and can vary wildly due to factors such as depth, orientation, your detector’s settings, and the effect of other metal objects in the same proximity.

If you would like to contribute readings for other detectors, we would be happy to put them here and credit you with them.  Also, If you see anything that looks out of norm with your experience, please comment below and we’ll take another look at it!


Possible Target MineLab e-Trac Fisher F-75
Shotgun Shell Casing 12 23
US Shield Nickel 13 28
Typical 14k Female Diamond Ring 13 27
Pull Tab 13 33
US V Nickel 14 30
US Buffalo Nickel 14 30
US Jefferson Nickel 14 30
US War Nickel 15 31
Female 14K Class Ring 17 33
US Gold $2.50 22 53
US Indian Cent (1859-1864) 22 45
US Flying Eagle Cent 23 47
Typical Mens 14K Wedding Band 30 62
US 3 Cent Piece (Silver) 31 56
US Gold $5 31 58
Civil War Three Ringer 34-35 54-60
US Indian Cent (1864-1909) 36 60
US Zinc Cent 37 62
US Seated Half Dime 37 61
US Gold $10 38 65
US Two Cent Piece 40 67
US Silver Dollar 01-41 90
US Half Cent 41 67
US Wheat Penny 42 67
US Bust Dime 43 67
US Gold $20 44 69
US Roosevelt Dime (1965+) 44 71
US Memorial Cent 44 70
US Roosevelt Dime (Silver) 46 70
US Mercury Dime 45 70
US Seated Dime 45 69
US Large Cent 46 81
US Barber Dime 46 71
US Roosevelt Dime (-1964) 46 70
US Seated Quarter 46 79
US Washington Quarter (1965+) 46 82
US Seated 1/2 Dollar 11-46 87
US Barber 1/2 Dollar 11-46 87
US Walking 1/2 Dollar 10-46 89
US Barber Quarter 47 81
US Standing Liberty Quarter 47 80
US Washington Quarter (-1964) 47 82
US Kennedy Half Dollar 47 87
CIVIL WAR PLATE 36 80

Photo Credits

Various charts Flickr:  Some rights reserved by GrapeCity



There are 3 comments for this article
  1. OZARKS at 12:50 pm

    Great Article! I personally think everyone should air test their machines themselves versus finding the numbers online. Sometimes they will find that the numbers are slightly different, and that can make a difference. 🙂 I also feel like a test garden is more accurate for the numbers as air tests aren’t all that accurate when the coins aren’t in the ground. Loving the articles, keep ’em coming!

Discuss This Article