Resistors are available in a large amount of different packages. Besides rectangular surface mount resistors,  axial resistor and MELF packages also draw users' close attention. The size of axial resistors is not as standardized as the SMD resistors and different manufacturers often use slightly different dimensions. Furthermore the size of an axial resistor depends on the power rating and the type of resistor such as carbon composition, wirewound, carbon or metal film. The following drawing and table give an indication of the dimensions of common carbon film and metal film axial resistors. Whenever the exact size needs to be known, always check the manufacturer datasheet of the component. PMRY series and MCC series axial resistor of Microhm Electronics follow below rules.

Power rating	Body length (l)	Body diameter (d)	Lead length (a)	Lead diameter (da)
Watt	mm	mm	mm	mm
1/8 (0.125)	3.0 ± 0.3	1.8 ± 0.3	28 ± 3	0.45 ± 0.05
1/4 (0.25)	6.5 ± 0.5	2.5 ± 0.3	28 ± 3	0.6 ± 0.05
1/2 (0.5)	8.5 ± 0.5	3.2 ± 0.3	28 ± 3	0.6 ± 0.05
1	11 ± 1	5 ± 0.5	28 ± 3	0.8 ± 0.05

Sometimes surface mount resistors are also used as MELF packages (Metal Electrode Leadless Face). The main advantage of using MELF in stead of standard SMD packages is the lower thermal coefficient and better stability. The TCR of thin film MELF resistors is often between 25-50 ppm/K while standard thick film SMD resistors often have a TCR of > 200 ppm/K. This is possible due to the cylindrical construction of MELF resistors. This cylindrical construction also gives the package distinct disadvantages, mainly when the components have to be placed using pick and place machines. Because of their round shape a special suction cup and more vacuum is required. There are three common MELF package sizes: MicroMELF, MiniMELF and MELF. The following table lists the characteristics of these types.

Name		Code	Length	Diameter	Power
			mm	mm	Watt
MicroMELF		0102	2.2	1.1	0.2 – 0.3
MiniMELF		0204	3.6	1.4	0.25 – 0.4
MELF		0207	5.8	2.2	0.4 – 1.0

Microhm Electronics' MELF resistor HPMRY also conform to above standards.