Can someone please help me work out how much fabric I need for this?

[ZombiesAteMyCunnyFunt]

I have this dog bed for my dog, (well, I will when DP buys one this afternoon.) and I want to make one of these plastic bed liners for it. But I just can't seem to work out how much fleece I need for the bed and for a seperate cushion cover! The dogs mattress is 3" thick and will be the same measurement as the base of the plastic bed when I cut it down. The left over foam from cutting the mattress will be used to line the sides of the bed so it'll be nice and cosy for him.

Please help! I'm no good at working with numbers and it's giving me a headache!

I can't guess it from what you write, especially as I don't know dog beds at all -

BUT... If I say that the wide part of the bed is the "width" & the narrower the "Depth"

for the bed cover hold one end of a tape measure on the outside bottom edge of the dog bed so that you will be measuring the depth -

then run your tape measure up from the bottom edge to the top edge - & then over & down into the bed - then across the base of the bed to the centre point - now double this figure - & write it down & add 10 cm

Now for the - cushion - measure the depth of the base of the bed & write that down

IF the width of the bed base is wider than 28" then Double the figure for the cushion if less than 28cm you can cut the back & front of the cushion pad side by side from the single figure you get from measuring the depth of the base-, then add 10cm -

Add the the figure you get from measuring for the bed cover, to the figure for the cushion round up to the nearest 1/4 meter & the answer is the amount of fleece you need to buy - this is based o fleece being 60" wide, which all I've seen is

HTH