# Question #a5122

##### 1 Answer

Take the number of plaques in on your plate and multiply by 10. If you counted 1 plaque, you would get 10.

Multiply the number that you got in the previous step by the inverse of the number on your dilution tube.

For example, if the plate you selected was the

This final number is your virus titer, and represents the number of viruses (1,000) per ml of your original culture.

However, to minimize error, only plates containing between 10 and 100 plaques are counted, depending on the size of the cell culture plate that is used.

Otherwise the margin of error will be very large and perhaps unusable.