The first step to using the electricity calculator tool is to get comfortable reading your meter.

The key thing to note when reading your meter is the direction the dial hand is traveling.

Start Reading from left to right.

When standing in front of meter the leftmost dial is the first one you should read. It's hand turns clockwise and it gives you your first number when recording your usage. The next dial's hand turns counter-clockwise.The third dial from the left turns clockwise. The forth dial from the left turns counter-clockwise. The last dial, the dial on the far right turns clockwise.
So, reading dials from left to right: the pattern is clockwise, counter-clockwise, clockwise, counter-clockwise, clockwise.

Choosing the correct number

Now that you know the direction the dial hand is moving, you can easily read the dial. A simple rule of thumb is, if the dial hand is between two numbers, use the lower number. If the dial hand appears to be pointing at a number but it may be a little off, go ahead and go with the numer even though you are not sure if the hand is actually on the number.

Location

This tool works for both city and county residents. Depending on where you live the tax structure is different and makes a difference how your bill charges get tabulated. Make sure you always choose either 'city' or 'county' depending on where you live so the tool can apply the right tax formulas for you.

Show History Only

The meter ID you enter allows the tool to keep track of your activity. If you chose to see history from previous postings, your meter ID is all you would need in order to do that. A listing in chronological order will be displayed for you analysis. You must have input data using Add meter reading selection before you can use the history feature.

Add meter reading

This is where you start creating your history data. You should probably have access to your billing statement as you get started with the tool. On the statement you will find your meter ID, previous and present meter readings.

GRU reads your meter once a month, so the previous and present numbers on your bill show the amount of kilowatts you used in a billing period.

The GRU calculator tool gives you the ability to monitor your electricity usage on whatever cycle you choose. If you wish to see how much electricity you've use over a given period of time and have the taxes and fees added in for you, the calculator tool is the way to go.
The ideal scenario for using the tools would be to get a current meter reading the day GRU reads your meter. This allows you to be in sync with GRU. Now you can start entering your daily reading until the next time GRU reads your meter. If you enter each day from start to finish, you will have the most accurate usage information for your meter logged in the system for the billing period. You can now audit the electricity usage statement you receive from GRU for accuracy.

Add current

Selecting this option makes entering daily readings faster because the system automatically finds your previous reading. All you do is enter your meter number and the current day's reading.

The GRU calculator tool can be very effective when used correctly. Hands-on practice using the tool is the be way to become familiar with the tool's functionality.

A good plan of approach for the average user would be to start out by checking the accuracy of the electric meter itself. This can be done by entering as close to a full month's daily readings as possible. Doing so will allow you to see your average daily KWHs used. Once you establish your daily average, you can spot any malfunctions, if there are any, as you you continue to use the tool.

Fees are determined based on the amount of Kilowatt hours used, so your attention should be on KWHs rather than on dollar amounts. Daily dollar amounts reflect Kilowatt hours used that will always be less than the 850 KWH threshold that separate tier1 and tier2 charges. In other words, if you used the tool to take a daily reading everyday of your billing period and totaled all the daily reading charges, the amount you get will not be accurate and will not match the amount on your billing statement. The reason being your daily KWH totals were always less than 850 (if you had a daily KWH reading of over 850, that would be very unusual) which keeps you in tier1 usage for the entire billing period.
However, it is possible to use 850 KWH or less during a billing period but that too is unusual.

Try taking a picture of your meter daily and entering the readings into the GRU calculator at a convenient time. If your meter ID is something you can't memorize, you can use any preferred ID for your meter ID in GRU calculator. All your meter history you enter into the tool is tied to your meter ID.