Hopped Extracts IBUs

I have a can of muntons hopped extract. It says 17-31 IBUs but there’s no mention to the volume of the batch. Would it be 5 gallons, I think that’s what the kit it came in was. I got it in a beer kit that was a gift and pieced out everything else. I was going to use it to check some yeast I harvested and maybe end up with 2.5 gallons of beer.

If the kit was purchased in the US it is 5 gallons. If it was from AU or UK it is 23 litres.

Thanks I changed my plan, its now going to become 3 gallons of pressure canned starter

Check the OG to have a healthy starter wort.