# Costs

If your network traffic costs you money, you can set up DU Meter to track your costs. DU Meter rules are
flexible and can be adjusted to conform to the accounting practices of most service providers. What happens
when a rate or the free allowance changes in the middle of a month is explained in [Data transfer costs calculations](https://www.hageltech.com/support/kb/du/data_transfer_costs).

### Calculate costs

By default costs are off. Specify whether all network traffic should be assigned a monetary value, or only
received or only sent traffic.

### Billing period

How often you are billed. First date of the month and week are specified in the
[History](https://www.hageltech.com/support/kb/du/using/options/database) options.

### Free allowance

Some providers give you a "free" allowance that you can use each month, and only "extra" traffic costs you
money. Specify this threshold here.

### Normal rate

Specify how much each megabyte of network traffic costs. If you are billed in kilobytes or gigabytes, multiply
or divide your cost by 1024, accordingly.

### Reduced rate

Some network providers have a reduced rate during off-peak time, for example during the late night hours or on
Saturday and Sunday. If you have such a provider, you will need to specify two things: the rate itself (how
much data costs during the reduced rate hours) and when this rate is in effect.

### Reduced rate hours

To configure the reduced rate hours, click with your mouse in the grid. Columns correspond to hours (from 0 to 23,
using 24-hour format) and rows correspond to days of the week. When you click on the cell, it changes color from
green to blue and vice versa. Blue corresponds to normal rate, and green to reduced rate.

For example, if your reduced rate is in effect every Sunday from 5PM to midnight, click on cells in the first
row from 17 to 23.