What Is an NMI (National Metering Identifier)?

What Does NMI Stand For, and How Does an NMI Differ From a Meter Number?

Last Updated: 2026-08-20

Key Takeaways

What is an NMI? It is a unique number that identifies one electricity connection point in Australia's National Electricity Market.
What does NMI stand for? It stands for National Metering Identifier. AEMO, the market operator, uses that full term.
NMI vs meter number: the NMI identifies the connection point, and the meter serial number identifies the physical meter installed there.
The NMI does not change when your meter is replaced. The meter serial number does change on replacement.
Most NMIs are 10 characters long. Some are shown with an 11th character, which is a check digit.
Your electricity distributor allocates the NMI. Retailers, distributors, and AEMO all read the same number.

What Is an NMI, and What Does NMI Stand For?

NMI stands for National Metering Identifier. An NMI is a unique number that identifies one electricity connection point in Australia's National Electricity Market.

A connection point is the place where the electricity network meets a property. It is where the wires from the street end and your premises begin. Every connection point in the market has its own NMI.

An NMI identifies an electricity connection point. It does not identify a person, an address, or a physical meter. Your customer account, your street address, and your meter are each recorded separately.

National Metering Identifier Meaning, in Plain Terms

The NMI answers one question for the electricity industry: which connection is this?

It identifies a connection point: the NMI belongs to the point where the network meets the property, and it stays there.
It is separate from your account: your account number identifies your relationship with your retailer. The NMI identifies the connection.
It is separate from your address: one street address can be written several ways, and one address can hold several connection points.
It is separate from your meter: the meter is equipment installed at the connection point. Replacing that equipment leaves the NMI unchanged.

What Does an NMI Look Like?

Most NMIs are 10 characters long, and some are shown with an 11th character on the end. The exact pattern depends on the network area. Treat the examples below as typical only.

The anonymised sample NMI used across this site is 6200000000. That is 10 characters, all numeric.

What to expect in the characters

Length: usually 10 characters, and sometimes presented as 11.
Numbers and letters: many NMIs are entirely numeric, and in some network areas an NMI includes letters.
The opening characters: these often indicate the distributor for the area. Victorian NMIs commonly begin with 6, and some Queensland NMIs begin with the letters QB.
The 11th character: where it appears, it is a check digit calculated from the first 10 characters.

Why an NMI Sometimes Has an 11th Character

A check digit is an extra character worked out from the characters before it. Mistype one digit of the NMI, and the check digit no longer matches, so the receiving system can reject the entry.

Bills often show the 10-character NMI, while some online portals ask for all 11 characters. Our NMI Checksum Digit Calculator works out the missing 11th character from the 10 you already have.

Try our NMI Checksum Digit Calculator Tool

NMI vs Meter Number Explained

The NMI and the meter number are commonly mixed up. The meter number is also called the meter serial number, and the manufacturer prints it on the physical meter.

These two identifiers change independently of each other. The table below sets them side by side.

Question	NMI	Meter serial number
What does it identify?	The electricity connection point	The physical meter installed at that point
Does it change when the meter is replaced?	No	Yes
Who allocates it?	Your electricity distributor	The party that installs the meter
Typical form	10 characters, sometimes shown as 11	Varies by manufacturer and meter type
Where you normally see it	On your electricity bill	On the meter itself, and usually on the bill too

Why the Difference Matters to You

When a smart meter replaces an older meter at the same address, an installer fits new equipment with a new meter serial number. The connection point is untouched, so the NMI carries on as before.

The NMI identifies the connection point and does not change when the physical meter is replaced. The meter serial number identifies the device and does change on replacement.

Both numbers usually appear on the same bill, a few lines apart. For step-by-step instructions on telling them apart, see How to Find My NMI on My Electricity Bill.

Who Assigns and Uses Your NMI?

Your electricity distributor allocates the NMI. The distributor is also called a DNSP, short for Distribution Network Service Provider, and it owns the poles and wires in your area.

AEMO, the Australian Energy Market Operator, runs the National Electricity Market. AEMO keeps the central register of NMIs in a system called MSATS. Retailers, distributors, and AEMO all read the same NMI from that register.

Why an Address Alone Is Not Precise Enough

Addresses are written many ways: "12/5 Smith St" and "Unit 12, 5 Smith Street" describe one place. A billing system needs a single exact key.
One address can hold several connection points. A block of units, a farm with sheds, or a house with a studio may have more than one.
Addresses change: councils rename streets and surveyors subdivide lots. The connection point stays where it is.
Meters change: an upgrade replaces the equipment. The NMI keeps identifying the same connection.

You can browse more plain-language explainers of this kind in our info guides.

Energy Assessments Use Your NMI and Connection Details

Knowing your own NMI is exactly the kind of precise property detail a professional energy assessment records when documenting your connection.

If you would rather have a professional turn all of this into a clear, costed plan for your home, find out more about how our Energy Assessments can help you.

Frequently Asked Questions

What does NMI stand for? NMI stands for National Metering Identifier. AEMO uses that full term in its metering procedures.
What is a National Metering Identifier, in plain English? It is the unique number that identifies one electricity connection point in the National Electricity Market.
Is an NMI the same as a meter number? No. The NMI identifies the connection point, and the meter serial number identifies the physical meter installed at that point.
Does my NMI change when my meter is replaced? No. The NMI stays with the connection point, while the meter serial number changes with the new device.
How many digits does an NMI have? Most NMIs are 10 characters and some are shown with an 11th. Many are entirely numeric, and in some network areas an NMI includes letters.
What is the 11th digit of an NMI? It is a check digit calculated from the first 10 characters, and it catches a typing error. Our NMI Checksum Digit Calculator calculates it for you.
Who allocates my NMI? Your electricity distributor allocates it. AEMO keeps the central register of NMIs for the National Electricity Market.
Does my NMI change if I move house? Your new home has its own NMI. Each connection point carries a separate identifier.
Is an NMI the same as my customer account number? No. Your account number identifies your relationship with your retailer, and the NMI identifies the connection point.
Can one property have more than one NMI? Yes. A site with several electricity connection points, such as a block of units, has an NMI for each one.
Does every Australian property have an NMI? The NMI applies to connections in the National Electricity Market, which covers Queensland, New South Wales, the ACT, Victoria, South Australia, and Tasmania. Western Australia and the Northern Territory run separate arrangements.
Is an NMI the same as a MIRN? A MIRN identifies a gas connection. An NMI identifies an electricity connection point.
Where does the NMI appear on my bill? Retailers normally print it in the account or supply details area. For step-by-step instructions, see How to Find My NMI on My Electricity Bill.
What can I do with my NMI once I have it? The NMI identifies your connection when you deal with a retailer or a distributor. See What Is an NMI Useful For? for the detail.

Try our NMI Checksum Digit Calculator Tool

Glossary

AEMO: The Australian Energy Market Operator. It runs the National Electricity Market and keeps the central register of NMIs.
Check Digit: An extra character calculated from the characters before it, used to catch a typing error. An 11-character NMI ends in a check digit.
Connection Point: The place where the electricity distribution network meets a property. Each connection point has one NMI.
DNSP: Distribution Network Service Provider, usually called the electricity distributor. It owns the poles and wires in an area, and it allocates the NMI.
Electricity Retailer: The company that sells you electricity and sends your bill. It buys network services from your distributor.
Meter Serial Number: The number that identifies one physical meter, printed on the meter by its manufacturer. It changes when the meter is replaced.
MIRN: Meter Installation Registration Number — the unique identifier for one gas delivery point in Australia. It is 10 characters plus a check digit, and it begins with the digit 5.
MSATS: The Market Settlement and Transfer Solution, the AEMO system that holds the register of NMIs and the details recorded against them.
NEM: The National Electricity Market. It covers Queensland, New South Wales, the ACT, Victoria, South Australia, and Tasmania.
NMI: National Metering Identifier. The unique number that identifies one electricity connection point in the National Electricity Market.

Try our NMI Checksum Digit Calculator Tool