Probably 3m x 6mIt depends on the size of your lawn.
We have a two small (approx 6m*2m) at back of house, I can aerate those with a hollow tine fork, but, our front lawn is approx 7m * 8m, I have done it with a hollow tine fork, but, it is really tedious and hard work.
I have this type of thing, cheap, but, not really unto the task for a large lawn. https://www.ebay.co.uk/itm/Lawn-Gra...578482&hash=item447043569d:g:-VsAAOSwtBZf1-Of