So I got some bags of Muntons Hopped Spraymalt (Light Dried Malt Extract) on the cheap, so thought I'd have ago at brewing a beer with it.

The calculation Muntons gave me for calculating the IBU's that this stuff would give in a brew is as follows:

"1g of the product dissolved into 1l would deliver 0.29IBU. From this you can calculate your total bitterness as you change the amount you add and the total volume.

So, for 500g dissolved into 1l would give 145IBU (0.29 x 500 = 145).

If you were to use 2.5kg for a 23l batch, then 0.29 x 2500 = 725 725/23 = 31.5IBU"