What’s the Difference Between Ninja AF400UK and AF451UK? [UK Air Fryer Models Explained] 2026

So, what’s the difference between Ninja AF400UK and AF451UK? The biggest change in the air fryers is the AF451UK’s digital cooking probe and Smart Cook System. Both air fryers give you a generous 9.5-litre capacity, two independent drawers, six cooking programmes and SYNC and MATCH functions. The AF451UK can also monitor the internal temperature of your food, rather than relying on cooking time alone.

Is that extra feature worth paying for? If you regularly roast chicken, cook steaks or prepare thicker pieces of meat, it could be. But for chips, vegetables, frozen foods and most midweek dinners, the AF400UK already does much the same job. The two models also have slightly different controls and timer options, so let’s compare what you’ll actually notice.

Ninja AF400UK vs AF451UK: Quick Comparison

Here are the main differences at a glance. The comparison is formatted as a side-by-side table on larger screens and separate labelled product cards on mobile.

About the figures: This table is based on the supplied UK instruction booklets and manufacturer information. The timer limits are specific to those booklet editions. We haven’t listed exact exterior dimensions because current and older manufacturer pages give conflicting figures for the model codes; check the measurements of the actual unit before ordering.

Ninja AF400 vs AF451: What Are the Main Differences?

The AF451UK Adds a Digital Cooking Probe

The AF451UK’s probe is more than an ordinary kitchen thermometer. It stays in a suitable piece of food while it cooks, and the appliance shows the internal and target temperatures on its display. You can choose a food preset or a manual setting, and probe-controlled cooking stops when the selected result is reached.

Think of cooking chicken in one drawer and potatoes in the other. You can monitor the chicken’s progress while the second zone is running, without repeatedly guessing how many minutes are left. This is where the Smart Cook system earns its place.

There are a few catches. The manual says the probe works in Zone 1 only. It shouldn’t be used with frozen protein or cuts thinner than 1.5cm, and it must be positioned correctly in the thickest part of the food. The probe also needs cleaning by hand, not in the dishwasher.

Don’t rely only on a preset’s label for food safety. The Food Standards Agency’s cooking guidance explains safe internal temperatures and how to check food with a clean thermometer.

The Control Panels Are Different

The AF400UK uses a central rotary START/STOP dial to select a cooking programme, alongside separate temperature and time arrows. The AF451UK has dedicated cooking-function buttons, arrows, a separate START/STOP button and its PROBE control.

One isn’t automatically easier than the other. If you prefer to choose a programme, time and temperature and get cooking, the AF400UK’s dial is straightforward. The AF451UK has more options to navigate when you use the probe, but that’s the point of the upgrade.

There Is a Small Air Fry Timer Difference

A detail you might miss in shop descriptions is that the supplied AF400UK manual lists Air Fry times of up to 60 minutes, while the supplied AF451UK manual allows up to 90 minutes. That is unlikely to matter for chips or reheating leftovers, but could make longer cooking sessions more convenient. The figures refer to these instruction booklet editions.

What’s the Difference Between Ninja AF400UK and AF451UK in Everyday Use?

For most everyday food, surprisingly little. Both models give you two independent cooking zones and the same six programmes: Max Crisp, Air Fry, Roast, Reheat, Dehydrate and Bake. Both use a fixed 240°C Max Crisp setting, and neither manual requires a separate preheat for ordinary use.

Both also have SYNC, which coordinates different dishes so they finish together, and MATCH, which copies the settings from one drawer to the other. You can use either machine with just one drawer when you don’t need to cook a full family meal.

If you’re still weighing up the format itself, have a look at our guide to whether a dual-basket air fryer is worth it. The two-drawer advantages are largely shared by these models.

What’s the Difference Between the AF400UK and AF451UK Specifications?

Capacity: Both Are 9.5-Litre Air Fryers

Each has two 4.75-litre drawers, so the AF451UK doesn’t give you any more room for food. You’re paying for additional cooking control rather than extra capacity. That makes the choice easier: if both will fit the food you want to cook, the probe and price matter much more than the litre figure.

For practical advice on portions, see our Ninja air fryer sizing guide for a family of four. If you’re keen on cooking Sunday lunch, our guide to what size air fryer fits a whole chicken covers the shape and space considerations.

Power: Both Are Rated at 2,470W

Both instruction booklets specify 2,470 watts. That doesn’t mean either uses exactly 2.47kWh for every hour of cooking; heating elements cycle, and usage depends on the food, temperature and cooking time. A built-in probe doesn’t by itself show that the AF451UK costs more to run.

Our UK air fryer running costs guide explains the difference between the power rating and the electricity a meal actually uses.

Dimensions and Ventilation Need Checking

These are similarly sized countertop machines, but we’d be wary of treating every dimension listed online as definitive. Current and older Ninja product pages provide inconsistent outer measurements for the same model codes. If you’re buying for a narrow worktop gap or beneath cupboards, confirm the exact dimensions with the seller before you buy.

One worthwhile manual detail: Ninja’s AF451UK booklet specifies at least 15cm clearance above and on all sides for air circulation. The supplied AF400UK booklet asks for adequate clearance without giving a number in that section. For either model, don’t cover the vents or push the machine against surrounding surfaces. Electrical Safety First has further UK air fryer safety advice.

Cleaning and Included Accessories

Both models come with two non-stick drawers and two removable crisper plates. Their manuals list the drawers and plates as dishwasher-safe, although Ninja recommends hand-washing the drawers to help them last longer. The AF451UK adds the digital cooking probe, which is not dishwasher-safe.

For more information, read our article on Ninja air fryer drawers and dishwasher cleaning. We’ve also compared which Ninja air fryers have ceramic-coated components and explained PTFE coatings in Ninja models; adding a probe doesn’t in itself change a drawer’s material.

Is the AF451UK Smart Cook System Worth Paying Extra For?

We’d say yes if you regularly cook meat or fish and would actually use a leave-in thermometer. The ability to see internal temperature rather than judge by the clock can be especially helpful for a larger joint or thick chicken breast, with vegetables cooking alongside it.

But if your air fryer is mostly used for chips, frozen snacks, roasted vegetables and leftovers, it’s difficult to justify a large premium for the probe. Both machines already have the same capacity and everyday cooking functions.

• Choose the AF400UK if you want dependable dual-zone cooking and a simpler control layout, especially when it’s cheaper.
• Choose the AF451UK if you regularly cook larger pieces of meat or fish and value built-in temperature monitoring.
• Check the actual price gap before deciding. A modest premium for Smart Cook may be worthwhile; a large one makes less sense if you’ll rarely use it.

Ninja AF400UK and AF451UK Deals: What Should You Compare?

Promotions can turn the expected price order upside down, so don’t assume the AF400UK will always be the cheaper choice. Instead of quoting a deal that may disappear tomorrow, we’d compare the full UK model code, whether the product is new or refurbished, delivery costs, return terms, guarantee and included parts.

For the AF451UK, check that the digital cooking probe is actually included. Some listings use very similar product photographs, and a low price isn’t a bargain if the bundle is missing the feature you wanted.

Where Can I Buy a Ninja AF400UK or AF451UK in the UK?

Look for the full model number from Ninja directly, or check established UK retailers such as Argos, Currys, John Lewis, AO and Amazon UK. Availability and promotions vary, and you may also encounter refurbished or special-edition variants.

The manufacturer’s UK pages are helpful for identifying the models and their listed accessories: Ninja AF400UK product page and Ninja AF451UK Smart Cook product page. Check the exact variant you’re buying rather than relying on a shortened name.

Which Is Better, Ninja AF400UK or AF451UK?

We’d choose the AF400UK for most everyday air frying if the price is noticeably lower. You get the same total capacity, two cooking zones and all six core functions. It doesn’t feel like a stripped-down option just because it lacks a probe.

The AF451UK is better suited to people who will actually use Smart Cook. If a built-in meat-and-fish probe would make your regular meals easier, it’s a worthwhile feature rather than just another button.

Ultimately, what’s the difference between Ninja AF400UK and AF451UK for the person buying one? Not extra drawer space or another standard cooking mode, but the probe, the controls and a small timer difference. Buy according to the meals you cook and the price gap in front of you.

Frequently Asked Questions

Is the Ninja Dual Zone Air Fryer AF400 the Same as the AF400UK?

AF400 is commonly used as shorthand for AF400UK, but don’t assume every listing without the UK suffix is an identical UK-market appliance. Check the complete code, plug and bundle contents, particularly for imported or refurbished stock.

Is the Ninja Dual Zone Air Fryer AF451 the Same as the AF451UK?

AF451 is often shorthand for AF451UK, but the suffix still matters. Check that the model is AF451UK and that the Smart Cook digital probe is included.

Can You Use Only One Drawer on the AF400UK and AF451UK?

Yes. Both instruction manuals explain how to run a single zone. You don’t have to fill both drawers for a small meal.

Can the AF451UK’s Probe Be Used in Both Drawers?

No. The built-in probe works in Zone 1 only. You can still use Zone 2 and coordinate the two zones with SYNC or MATCH.

Do the AF400UK and AF451UK Have the Same Cooking Programmes?

Yes: Max Crisp, Air Fry, Roast, Reheat, Dehydrate and Bake. The AF451UK adds probe control, not a seventh standard programme.

Do These Ninja Air Fryers Need Preheating?

Neither supplied manual requires preheating for normal cooking. Follow the relevant recipe or cooking chart and check your food as it cooks.

Are the AF400UK and AF451UK the Same Size?

Both have 9.5-litre total capacity split between two 4.75-litre drawers. For outer dimensions, verify the particular seller’s measurements: online manufacturer specifications aren’t fully consistent across versions.

Are Both Ninja Models Dishwasher-Safe?

Both manuals list drawers and crisper plates as dishwasher-safe, though hand-washing the drawers is recommended to help preserve them. Do not put the AF451UK’s probe in the dishwasher.

What’s the Difference Between Ninja AF400UK and AF451UK If I Don’t Cook Meat?

If you won’t make use of the Smart Cook probe, their everyday cooking features are very similar. We’d usually choose the cheaper AF400UK in that situation.

UK Manufacturer Manuals and Further Reading

We checked the two official UK instruction manuals and quick-start information supplied for this article. The main sources are:

• Ninja AF400UK Instruction Booklet — controls, functions, cleaning and power rating (printed pages 5–14).
• Ninja AF400UK Quick Start Guide — SYNC/MATCH cooking and the six programmes.
• Ninja AF451UK Instruction Booklet — Smart Cook probe, Zone 1 limitation, controls and cleaning (printed pages 5–16).
• Food Standards Agency: Cooking Your Food — independent UK cooking and probe guidance.
• Electrical Safety First: Air Fryers — independent UK electrical safety guidance.