When you use the powder, 1/4t is equal to almost 500 mg. So if you want 250mg twice a day, just guesstimate half of a 1/4 scoop. If you get a little more, you're okay. A little bit less isn't a big deal either. What you want to be sure of is keeping the lysine in their system since it will be excreted out in urine. That's why you do it twice a day. If they have an active flare up of herpes, then up it to 500mg twice a day. With mine, I have found that the flare up dose is her maintenance dose. If we cut it back, she starts having symptoms of a flare up.