Yeast slurry question

On Mr Malty if repitching yeast, it gives the amount of slurry you need in ml. I rinse my yeast after a batch right in my fermenter. I put cooled boiled water on the cake give it a stir and let it settle out for 15-20 min then I open my valve and fill whatever I’m using to store it in. My question is would the amount of slurry that mr malty is referring to be the amount once it’s settled to the bottom which takes a good day at room temp? Just seems like a lot of yeast to me. My current batch says I need 400 ml. 20 gal 1.057.

Are you talking about Ale yeast because when I plug in your numbers I get 284 ml. That seems correct because with that gravity it runs about 70 ml for every 5 gal for a thick slurry.