What Is a MIRN Number on a Gas Bill?

What the Meter Installation Registration Number on your gas bill identifies

Last Updated: 2026-09-16

Key Takeaways

• A MIRN is the unique number for one gas delivery point in Australia. MIRN stands for Meter Installation Registration Number.
• A MIRN number is 10 characters plus a single check digit, which makes 11 in total. The check digit is always a numeric digit.
• A MIRN is an NMI issued from the gas number range that begins with 5, so one check-digit calculation serves gas and electricity.
• The MIRN on a gas bill identifies the delivery point. The meter serial number identifies the physical meter, and it changes when the meter is replaced.
• Your MIRN stays the same when you switch gas retailer, because the number belongs to the delivery point.
• New South Wales and the ACT call the same number a DPI (Delivery Point Identifier).

What a MIRN Identifies on a Gas Bill

A MIRN identifies one gas delivery point — the single point at which the gas network delivers gas to a property. Your gas retailer, your gas distributor, and the market systems behind them all use it to mean your connection.

Several numbers can appear on the paperwork for one property, and each names a different thing.

• Street address: names the building.
• MIRN: names the gas delivery point.
• Meter serial number: names the physical gas meter.
• Gas account number: names your contract with a retailer.

MIRN Meaning and the Names on Your Bill

MIRN stands for Meter Installation Registration Number. The industry expands the acronym inconsistently, so the same number also appears under other formal names.

• Metering Installation Registration Number
• Meter Installation Reference Number
• Meter Identification Reference Number
• Meter Indicator Reference Number

All of them name one thing. Because a MIRN names a single gas connection, people sometimes call it a gas connection number in everyday speech.

What Does a MIRN Look Like?

A MIRN is 10 characters plus a single check digit, which makes 11 characters in total. The check digit is always a numeric digit. Every MIRN number in Australia begins with the digit 5.

AEMO (the Australian Energy Market Operator) publishes 5600012357 as a sample gas identifier. With its check digit added, the full sample reads 56000123579.

Which forms want all 11 characters varies. Retailer transfer forms and new connection applications commonly ask for the full number (subject to confirmation).

The check digit is calculated from the first 10 characters, and it catches typing errors. An off-the-shelf validator returns a wrong check digit for a MIRN. Our free MIRN Checksum Digit Calculator uses the correct method.

Try our MIRN Checksum Digit Calculator Tool

Why a MIRN Is an NMI from the Gas Range

The Australian gas market did not build its own numbering system. It adopted the National Metering Identifier (NMI), the electricity market's unique number for one connection point. Gas took the block of NMIs that begins with 5.

AEMO reserved that whole range for gas and agreed to issue no electricity NMIs inside it. A MIRN is therefore an NMI, and gas holds one part of the NMI range.

The check digit therefore uses the NMI checksum method, and the length is the same for gas and electricity. An Australian meter identifier beginning with 5 is a gas identifier.

For a general overview of the electricity side of the same numbering system, see our info guide on what an NMI is.

MIRN vs Meter Serial Number

Gas customers frequently enter the meter serial number when a form asks for the MIRN. Both numbers appear on a gas bill, often near each other.

The MIRN identifies the delivery point. The meter serial number identifies the physical device at the property. A technician who replaces the meter changes the serial number, and the MIRN stays the same.

Victorian meter serials often take the form 1234AB. New South Wales meter serials often take the form AB123456. South Australian meter serials are typically eight digits (subject to confirmation).

A number in one of those shapes is the serial number of the meter, so a form asking for the MIRN needs a different number from your bill.

Does a MIRN Change When You Switch Gas Retailer?

No. The MIRN belongs to the gas delivery point. It does not change when you change retailer, and it does not change when a technician replaces the meter.

That permanence is why a retailer asks for it. A transfer request names the delivery point, so the incoming retailer can pick up the correct connection.

Finding Your MIRN on a Gas Bill

Where is my MIRN? Most gas retailers print it on page 1, in a Your Details or Customer Number section. The position varies by retailer.

• Some retailers print it further into the bill instead of on page 1.
• Near the meter serial number, which retailers usually print on the same bill.
• On a gas connection form or a retailer transfer form you have already completed.

Once you have the first 10 characters, our MIRN Checksum Digit Calculator works out the 11th.

Try our MIRN Checksum Digit Calculator Tool

The free tools for the gas meter identifier on your bill sit together on our MIRN and DPI tools page.

Which States Say MIRN and Which Say DPI?

A MIRN and a DPI are the same identifier under two names. The gas market itself uses MIRN in every Australian state.

• MIRN: used on its own in Victoria, Queensland, South Australia, and Western Australia.
• DPI (Delivery Point Identifier): the customer-facing name in New South Wales and the ACT, where the two terms mean the same number.
• MIRN in the market systems: the term retailers, distributors, and AEMO use in every state.

For why New South Wales uses its own word for it, see our info guide on what a DPI is, or browse our info guides.

Energy Assessments for an All-Electric Home

Either name belongs to the gas delivery point. If you plan to get off gas, an energy assessment can confirm whether an all-electric home suits your household.

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.

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Frequently Asked Questions

• What does MIRN stand for? Meter Installation Registration Number. The industry also writes Metering Installation Registration Number and Meter Installation Reference Number for the same number.
• What is the MIRN meaning in plain English? It is the unique name for the point at which the gas network delivers gas to a property.
• How many characters is a MIRN number? 10 characters plus one check digit, which makes 11 in total. Many gas bills print only the first 10.
• Is a MIRN number gas-only, or does it also cover electricity? A MIRN names a gas delivery point. Electricity connection points use NMIs from outside the range that begins with 5.
• Is a MIRN an NMI? Yes. A MIRN is an NMI issued from the gas range, so the same check-digit calculation applies to both.
• Why does a MIRN begin with 5? AEMO reserved the number range beginning with 5 for gas. The first character is 5 for any MIRN number Australia wide.
• Which part of a gas bill shows the MIRN? Most retailers print it on page 1, in a Your Details or Customer Number section. The position varies by retailer.
• Is a MIRN the same as my gas meter serial number? No. The MIRN names the delivery point, and the serial number names the physical meter at the property.
• Does my MIRN change when I switch gas retailer? No. The MIRN belongs to the gas delivery point, so a retailer switch leaves it unchanged.
• Does my MIRN change when the gas meter is replaced? No. The meter serial number changes, and the MIRN stays with the delivery point.
• Is a MIRN the same as a DPI? Yes. They are two names for one identifier, and New South Wales and the ACT use the DPI name.
• What is the 11th character of a MIRN for? It is a check digit calculated from the first 10 characters, and it catches transcription errors.
• Why did an online validator reject my MIRN? General-purpose check-digit validators use a different method, so they return a wrong digit for a MIRN.
• Can I look up my MIRN from my street address? No public lookup turns an address into a MIRN. Your gas bill, your gas retailer, or your gas distributor is the reliable source.
• What do people mean by a gas connection number? It is an informal name for the MIRN, because the number identifies one gas connection.
• Do all gas forms ask for all 11 characters? The requirement varies. Retailer transfer forms and new connection applications commonly ask for the full 11 characters (subject to confirmation).

Glossary

AEMO

Australian Energy Market Operator — the body that administers the National Electricity Market and defines and maintains the NEM12 specification.

Check Digit

The 11th digit of a full NMI — calculated from the first ten digits to detect transcription errors; some DNSP portals require it. Also called a 'Checksum'.

Delivery Point Identifier (DPI)

The customer-facing name used in New South Wales and the ACT for the same gas identifier that the rest of the Australian gas market calls a MIRN.

Gas Delivery Point

The single point at which the gas network delivers gas to a property. One MIRN identifies one gas delivery point.

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.

NMI

National Metering Identifier — the unique 10-digit identifier for an electricity connection point (11 with the Check Digit), permanent to the property. Note that the electricity connection point identified by the NMI, typically has multiple NMI Suffixes, and can have multiple Physical Meters. See also: Check Digit, NMI Suffix.