Parachute size table 
There are plenty of calculators around to size parachutes, but the following table will give a quick guide to the right size. It assumes a round parachute. Recommended descent rates vary between 15 and 20 feet per second, depending on the landing surface, toughness of the rocket and how little walking you want to do. The rocket mass includes an empty motor case (i.e. the condition after separation), and parachute size is given in inches, rounded to the nearest likely size available. 
Rocket mass 	Diameter (inches)
for 15 ft/s descent 	Diameter (cm)
for 15 ft/s descent	Diameter (inches)
for 20 ft/s descent	Diameter (cm)
for 20 ft/s descent	
100g	12	30,5	10	25,4	
200g	18	45.7	14	35,6	
300g	22	55,9	18	45,7	
400g	26	66	20	50,8	
500g	30	76	24	61	
600g	32	81	27	68,5	
800g	36	91,5	30	76	
1kg	42	106,7	36	61,5	
1.5kg	50	127	42	106,7	
2kg	60	152	48	122	
3kg	72	183	56	142	
4kg	84	213	66	168	
5kg	93	236	72	183	

For other sizes see http://www.rocketreviews.com/cgi-bin/myemrr/descent33_distr.cgi