What is half hourly metering?
Half hourly metering measures your electricity use in 30 minute blocks and settles your bill on what you actually used in each of those blocks, instead of a supplier’s rough estimate of when you probably used it. It sounds like plumbing, and it is, but it quietly decides whether your business pays a fair price or funds someone else’s guesswork.
Written by Kofi, business energy desk. Last updated 16 July 2026.
Most firms never think about how their meter is read. Suppliers are perfectly happy with that. An estimated bill is easy to pad with assumptions about your usage, and the longer nobody looks, the longer you keep paying for timing and capacity you may not actually need. That’s the quiet cost of doing nothing. It’s the bit worth fixing.
The good news is that the whole market is moving to half hourly metering anyway, and if you understand what’s changing you can turn it from an admin headache into a genuine lever on your bill.
Who needs a half hourly meter?
Not every business has a dedicated half hourly meter, and until recently most didn’t. The traditional rule is about size: any site drawing more than 100 kVA of maximum demand in any half hour has to be on a half hourly meter (checked July 2026, per Ofgem and industry guidance). Those are your larger premises, factories, big retail units and busy offices.
Smaller sites have historically sat in “profile classes” instead, where a standard usage shape is assumed rather than measured. Back in 2017, a rule change known as P272 moved medium businesses in profile classes 05 to 08 onto half hourly settlement. The wider reform now under way, called MHHS, finishes the job for everyone else.
Here’s the picture at a glance.
| Meter or profile type | Typical business | How it’s settled today |
|---|---|---|
| Profile classes 03 to 04 | Smaller shops, offices, cafes | Estimated usage shape, moving to half hourly under MHHS |
| Profile classes 05 to 08 (P272) | Medium sites | Half hourly since 2017 |
| 100 kVA plus demand | Large premises, industrial units | Dedicated half hourly meter, already settled half hourly |
If you’re not sure which one you are, your electricity bill or your meter number (the MPAN) will tell you, and a quick look at your business energy contract is a sensible first move before anything changes.
What is MHHS and why does it matter in 2026?
MHHS stands for Market wide Half Hourly Settlement, and it’s an Ofgem led reform that ends estimated electricity billing for good. The plan is that every meter capable of it gets settled on real half hourly data rather than an assumed profile, so bills reflect what you genuinely used and when.
The rollout is happening in phases between September 2025 and July 2027, with suppliers migrating their meter points across that window (checked July 2026, per Ofgem and supplier programme updates). A key industry milestone, when suppliers must be fully ready to handle meters under the new model, is set for October 2026, and from December 2026 suppliers are expected to settle smart and advanced meters half hourly as standard.
None of this arrives as a letter marked “your bill is going up”. It happens quietly, in the background. But it changes what your usage data can do, and that’s where the money is. You can read the detail in Ofgem’s guide for businesses on moving to half hourly reads.
Will half hourly metering make my bill go up or down?
Honestly, it depends on your business, and anyone who promises you a saving before seeing your usage is guessing. The point of half hourly metering is accuracy, not a discount, and accuracy cuts both ways.
Since P272 arrived in 2017, many medium businesses saw little change or a small drop once their bills reflected real usage, while some paid more because the estimate had been flattering them. If most of your electricity is used in the cheaper parts of the day, precise settlement tends to work in your favour. If you’re heavy in the expensive early evening peak, it can expose that.
There’s also a trap on the fixed side of the bill. Larger sites agree an “available capacity”, and it’s common to be signed up for far more than you’ll ever draw, then charged for it every month. Industry estimates put that waste at anywhere from a few hundred to several thousand pounds a year on bigger sites, depending on your agreed capacity, so it’s worth checking rather than assuming. Treat any figure as an estimate until your own data confirms it.
The real risk isn’t the switch to half hourly metering. It’s sitting on an expensive out of contract or deemed rate while it happens, which is exactly the default suppliers rely on.
How to use half hourly metering to cut your bill
The businesses that come out ahead treat their half hourly metering data as management information, not paperwork. Here’s the practical version.
Before your next renewal
- Ask your supplier for your half hourly data, then look at when you actually use electricity across the day.
- Shift what you can (charging, heating, heavy equipment) away from the expensive late afternoon and early evening peak.
- Check your agreed available capacity against your real peak demand and query it if there’s a big gap.
- Compare business energy deals before your current one ends, so you never roll onto a deemed rate.
The last point does the heavy lifting. The single most expensive thing a business can do is nothing, letting a contract lapse and drifting onto out of contract rates that are set to be uncompetitive on purpose. Half hourly data just makes it easier to find the deal that actually fits your usage pattern.
It’s the same logic we cover in our guide to the new Ofgem rules for brokers, and it sits alongside simpler wins like making sure you’re on the correct VAT rate. If you’ve never checked, it’s worth a look at how to cut the VAT on your business energy too.
When you’re ready, comparing takes a few minutes, and it’s the one step that turns better data into a smaller bill. Switcheroo is rated 4.45 out of 5 on Reviews.io, and any saving depends entirely on your site, your usage and the deals live at the time.
Frequently asked questions about half hourly metering
- How do I know if I have a half hourly meter?
- Check your electricity bill or your meter point number (the MPAN). Half hourly meters are usually flagged on the bill, and larger sites over 100 kVA of demand are always on one. If you’re unsure, your supplier can confirm it.
- Is half hourly metering compulsory for my business?
- For larger sites it already is, and under the MHHS reform running to 2027 all capable meters are being moved to half hourly settlement. You don’t have to do anything to be migrated, but it’s worth engaging with the change rather than ignoring it.
- Does a half hourly meter mean a bigger bill?
- Not automatically. It means a more accurate bill. Businesses that use most of their power in cheaper periods often benefit, while peak heavy users may see the true cost. Any change depends on your own usage, so treat estimates as a guide, not a promise.
- What is the difference between P272 and MHHS?
- P272 was the 2017 rule that moved medium businesses in profile classes 05 to 08 onto half hourly settlement. MHHS is the wider reform now finishing the job for the rest of the market between 2025 and 2027.
- Can half hourly metering actually help me save?
- It can, indirectly. Seeing exactly when you use electricity lets you shift usage off peak, right size your agreed capacity and pick a tariff that suits your pattern. The saving isn’t guaranteed and depends on your business, but the data makes a better deal easier to find.
