How much coolant do I need?

[JRC1]

Just fitting a Nissens radiator. What ratio of coolant to water do I need to use?

Thanks in advance.

[Tom5190]

Standard 16v set up holds 6.1 litres

Ive got a 1.1 sytem holds 5.7 litres and ive used 1.5 litre's of anti-freeze it's down to -20C which is enough for me.