Below is a loop sizing chart that outlines various loop sizes and their characteristics. All the numbers are approximated and actual results may vary. This chart gives you a good ballpark figure on what can be expected.

Loop Length (Feet)	Loop Width (Feet)	Number of Turns	Approximate Loop Inductance (uH)	Approximate Detection Height (Feet)
6 feet	4 feet	3	75uH	2.7 feet
8 feet	4 feet	3	100uH	2.7 feet
10 feet	4 feet	3	120uH	2.7 feet
12 feet	4 feet	3	145uH	2.7 feet
8 feet	6 feet	2	145uH	4 feet
10 feet	6 feet	2	90uH	4 feet
12 feet	6 feet	2	110uH	4 feet
10 feet	8 feet	2	120uH	6 feet
12 feet	8 feet	2	145uH	6 feet

Loop Sizing "Rule of Thumbs":
1) The MINIMUM loop inductance should be 50uH for stability.
2) The loop lead-in should have an inductance LESS THAN the loop inductance.
3) The detection height of the loop is approximately 2/3 of the shortest side of the rectangular loop.
4) Small motorcycles cause a frequency shift of 1% to 2% of the change of a standard vehicle.
5) The loop should have a MINIMUM of 2 turns.