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Octopus Agile explained: how half-hourly pricing works

Last updated: 10 August 2026

Most electricity tariffs charge you one flat price per kWh, all day, every day. Agile Octopus doesn't. Its price changes every half hour — 48 different prices a day — following the wholesale electricity market. That single difference is what makes it either the cheapest tariff you've ever been on, or a trap for the unwary.

Where the prices come from

Great Britain's electricity is traded ahead of time on wholesale markets. Every afternoon, a day-ahead auction settles a price for each half hour of the following day — high when the grid expects demand to outstrip cheap supply, low when there's plenty of wind and solar to go round. Agile takes those wholesale half-hourly prices, applies Octopus's published formula (which adds the usual costs of getting electricity to your door, and weights the early-evening peak more heavily), and turns them into the unit rates you pay.

The shape of a typical day is surprisingly consistent. Prices are usually lowest in the small hours — roughly midnight to 6am — when most of the country is asleep but the wind keeps blowing. There's often a second, shallower dip in the early afternoon when solar output peaks. And there's almost always a spike between about 4pm and 7pm, when everyone arrives home, turns on the oven, and boils the kettle at once. On many days that evening peak costs several times the overnight rate.

When tomorrow's prices appear

Octopus publishes the next day's half-hourly prices at around 4pm UK time each day, covering through to 11pm the following evening. That rhythm matters for planning: from late afternoon onwards you can see the whole of tonight and tomorrow, which is exactly when you'd load the dishwasher and set a delay timer. Before 4pm you can only see prices to 11pm today, so longer delays can't be scored yet — Cheap Hours works with today's remaining prices until the new ones land, then picks the fresh ones up within minutes.

The 100p cap — and negative prices

Agile's unit rate is capped at 100p/kWh, so a wild day on the wholesale market can't charge you more than that. The cap is a backstop, not a typical price — but it's worth knowing it exists, because on a cold, still winter evening the peak really can get close to it.

The opposite end is more fun: when the grid has more cheap generation than it needs — usually a windy night or a bright, breezy spring afternoon — wholesale prices can fall below zero, and Agile follows them there. In a negative half hour you are literally paid per kWh you use. It only happens a handful of times a year, but when it does, it's the best moment all month to run the tumble dryer. We've written a whole guide to plunge pricing.

Who Agile suits

Agile rewards flexibility. The people who do best on it share one habit: they can move their biggest electricity users — washing machine, dishwasher, tumble dryer, EV charger, immersion heater — out of the evening peak and into the cheap windows. If most of your usage is things you can shift, the arithmetic is strongly in your favour: the everyday appliance cycles that make up a big slice of a typical bill can often be run for half price or less just by timing them well.

Agile is a poorer fit if your usage is concentrated in the peak and can't move — for example if you must cook dinner electrically at 6pm every night and have little else to shift. Those households can end up paying more than they would on a standard tariff. It also asks a little of you: either a willingness to glance at prices, or a tool that does the glancing for you.

Things to know before switching

Cheap Hours turns Agile's 48 daily prices into one instruction per appliance — the exact delay-timer setting for the cheapest run. Free, no account needed.

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