What Length Furniture Cover Bungee Cord?

[mizfiesta]

It's for a 3/4 seater garden bench. I have covered the bench with a Vonhaus cover, and a friend suggested I should secure it further with a bungee cord to prevent it flying off -  but not sure what size to buy? Unless I can buy a pack of 6 smaller ones and they all join together? I've never used these before so I am clueless. I thought the only reason people used these was to just off tall objects! Who knew?!

[Buenchico]

Bungee cords generally shouldn't be stretched to more than about 50% of their original length. 

Looking at that the other way around, measure how long the cord will be when stretched and in place, then buy a cord that's roughly two thirds of that length or pehaps a little bit longer.  (I'd probably look for one that was around three quarters of the desired stretched length).

[mizfiesta]

Buenchico, thanks for your response. On your calculations I've worked out that I may need about 3.5 metres in length given that the approx diameter of bench is 5.28 metres. I'll try this, thank you.