Shark IZ251 Anti-Hair Cordless vacuum Review

The Shark IZ251 is a fantastic cordless vacuum for those with limited space – especially if you’re concerned about cleaning up pet hair. Let’s talk about why and share our testing – after all, it’s always best to be well informed when making a purchase of this size.


Overall Score

Basic Function & Special Features (30%)


Ease of Use (30%)


Maintenance (40%)



  • Price: £321.89
    • Editor’s Note: At the time of publication, this device was on sale. Its base price before the discount was £449.99.
  • Brand: Shark
  • Pros: Compact, flexible, powerful, great with pet hair and small, hard to reach places
  • Cons: Somewhat short battery life (45 minutes), long-ish charge time (2 hours)
  • Amazon Listing: Shark IZ215

The Ruling

While the Shark IZ251 has a relatively low battery life in comparison to the manufacturer’s claims, it’s a highly efficient, easily manoeuvrable, and compact cordless vacuum. It’s one of the best out there, and we say that with good reason – we’ve reviewed dozens of vacuums, and this was one of our top choices.

Let’s talk about why – shall we?

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Product Testing & Comparison

Shark vacuum extended

Our reviewer used a specific set of guidelines to rank each and every bit of this device to ensure the most accurate testing possible. She examined:

  1. Ease of Use
    • Weight
    • Dust Bag/Canister
    • Battery & Indicators
    • Flexibility and Maneouverability
  2. Maintenance
    • Filters
  3. Basic Function and Special Features
    • Modes
    • Dimensions and Attachments

We performed an extensive series of tests on every minor detail imaginable. Let’s get right into it!

Shark IZ251 Review

Let’s work our way through the review together. We’re going to detail exactly how we tested each part, and just for you, our reviewer took some pictures. Let’s get going.

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Shark IZ251: Ease of Use

This section will be broken down into the four sections listed above. Let’s see if Shark’s IZ251 holds up to the manufacturer’s claims, shall we?


compact vacuum

Our reviewer first examined the weight of the IZ251. This is a surprisingly important factor in a cordless vacuum that many seem to overlook. The weight of your cordless vacuum drastically impacts your ability to take it where it’s needed – the entire draw of a cordless device in the first place!

Our reviewer weighed the vacuum both with the battery and without using our standard review scale. When you first grab a battery-powered device, it’s often surprising how light it is – until you add the battery. Then you realize that the majority of the device’s weight comes from the most important part of the device. Luckily, with this particular item, the weight of the vacuum barely varies – battery or not.

Executive Summary: Regardless of whether or not you have the battery in, this vacuum weighs in just below 5 kilo (11 pounds).

This makes it incredibly simple to pick up and carry the vacuum wherever it’s needed. That means bonus points for manoeuvrability!

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Dust Bag/Canister

dust canister

This particular vacuum is bagless. In our eyes, that’s a plus – it’s never fun to try and clean out bagged vacuums, no matter how ergonomic the manufacturer claims it is to clean.

Luckily, Shark opted for a dust canister that’s incredibly easy to remove and clean (we’ll get to that in the maintenance section).

Our reviewer found that the dust canister was incredibly easy to remove and empty. It needs to be cleaned monthly (unless you clean regularly on a professional level), and its filters need annual replacement and regular (weekly/biweekly) cleaning.

Executive Summary: The dust canister for the Shark IZ251 is removable with the push of a button and requires little regular maintenance. It should be cleaned monthly to ensure it stays in prime condition, and its filters need annual replacement, assuming they’re properly maintained.

Battery and Indicators

Next up is the battery itself. We’re going to be talking about a few things in this section: battery life, voltage, and low-power indicators, specifically.

With a voltage of 25.5 volts, this battery is right in the middle range of voltage for cordless vacuums (most range between 12-40 volts).

The manufacturer claims that it boasts an 80-minute battery life, though our reviewer discovered that this isn’t quite accurate. When she let a fully-charged battery run the vacuum until it died, it only lasted 45 minutes. She repeated this test several times, and the variance in battery life was negligible (+/- 1 minute).

Luckily, she found a few good things to note about the battery and its lifespan. First, she was able to easily clean her entire home – a 3-bedroom, semi-detached house. So while the battery life may be less than the manufacturer claims, it’s effective enough that you shouldn’t find yourself racing the battery to finish up a small-to-midsized home.

The battery indicator is in clear view on the front of the vacuum and uses a 3-bar measurement system. Once you reach the final bar, it’s time to let the battery recharge – which takes roughly 2 hours from dead to fully charged.

Executive Summary: While the battery life isn’t as long as claimed (80 minutes), its ~45-minute battery life is more than enough to clean a small-to-midsized home. The battery indicator is accurate and placed directly on the front for a simple warning for when you need to charge your battery – which takes roughly two hours from dead to fully charged.

While we were bummed that the manufacturer stretched the truth a bit, they still made an efficient and quick-to-charge battery.

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Flexibility and Maneouverability

Shark IZ251 folded under couch

Perhaps the most important part of a cordless vacuum is manoeuvrability. They’re designed to go wherever you can and help clean hard-to-reach areas such as under your couch or the small crevices of carpeted stairs.

This is where the Shark IZ251 shines. As you can see from the image above, this particular vacuum is designed to do two things – save your back, and clean the areas that traditional vacuums struggle with the most. The combination of a slim design and purposely flexible grip, alongside a detachable handheld vacuum, makes this a fantastic flexible device.

Our reviewer gave it a test by vacuuming under her low-sitting sofa, coffee table, and TV stands – each of which is generally inaccessible without moving the furniture when using a traditional vacuum.

Executive Summary: The Shark IZ251 is extremely flexible and provides near-effortless access to even the hardest to reach areas. Trust me – your back will thank you in the long run.

In short, the flexibility of this vacuum is nearly unparalleled, making it ideal for those who lack flexibility or who just don’t want to put unneeded stress on their back and knees.

Shark IZ251: Maintenance

Now it’s time to talk about the nitty-gritty details. Specifically, what does the maintenance for this vacuum look like?

Mostly, the maintenance for this particular device is pretty negligible.

The process is quite simple – remove the three filters (2 sponge-like filters placed before the motor, one after the motor) and run them under the tap. They can then be left to air dry, and generally take less than 24 hours to fully dry.

The dust canister is exactly the same. Once per month (give or take, depending on how regularly you use it and how dirty it gets) you simply remove the canister and run it under the tap. You can then air dry it and wipe it down with a soft cloth.

Our reviewer noted that the filters generally dried within 18 hours, though she recommends that you give them a full 24 hours – just so you don’t risk mould or mildew building up in the filters over time.

Executive Summary: The Shark IZ251 is incredibly easy to maintain. The filters need regular cleaning, as does the canister, but it’s as simple as giving them a rinse and letting them dry. The filter needs annual replacement, but beyond that, there is a very minimal time investment in cleaning and maintaining the thing.

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Shark IZ251: Basic Function and Special Features

Now let’s talk basics. We’ve gotten the technical stuff out of the way, so now we can move on to what makes this particular device special.


Shark IZ251 modes and attachments

The Shark IZ251 has three modes: carpet, hard floor, and boost.

Our reviewer tested each on their primary target – carpet for the carpet setting, hardwood for the hard floor setting, and boost for more stuck-on items.

She vacuumed a number of things, each of which came up with absolutely zero issues:

  • Pennies
  • LEGO pieces
  • Hair clips
  • Bobby pins
  • Sweets wrappers
  • Food crumbs
  • Pet hair

While she did note that some of the harder bits (pennies, LEGO pieces) would likely damage the unit over time, if you’re in a bind, this thing will suck up just about anything.

The boost function is specifically designed to pick up things that a standard vacuum would struggle with. Think of it as the nitrous boost to your vacuum “racecar.”

Executive Summary: The Shark IZ251 has three high-quality settings that work wonders on their specified surface – carpet, hard flooring, and boost. While it will pick up just about anything, our reviewer recommends using caution on hard items that could crack the interior.

The power that this vacuum displayed gave it a huge boost in our rankings. The boost function alone was enough to put our reviewer’s mind at ease in terms of performance.

Dimensions and Attachments

size and attachments

Now we get into the (arguably) boring stuff. Let’s talk about dimensions and attachments.

The Shark IZ251 has a detachable handheld vacuum to reach small spaces that comes into two parts. You can then attach a wide range of attachments, though our reviewer focused on the pet hair attachment (which worked wonders, by the way).

When folded and upright, the vacuum measures:

  • Folded:
    • Height: 27 in. (68.5 cm.)
    • Width: 9.5 in. (24.1 cm.)
    • Depth: 10.3 in. (26.1 cm.)
  • Upright:
    • Height: 42.5 in. (107.9 cm.)
    • Width (hose): 2.2 in. (5.5 cm.)
    • Depth: 10.3 in. (26.1 cm.)
  • Hose:
    • Max. Length: 37 in. (93.9 cm.)
    • Min. Length: 25 in. (63.5 cm.)
    • Diameter: 2.2 in. (5.5 cm.)

And then there are the attachments. We tested:

  • Pet hair attachment (motorised and multitool)
    • When tested in a home with a golden retriever, both pet hair attachments worked wonders. Our reviewer said it was one of the best pet hair attachments she’s tested.
  • 12″ crevice tool
    • Our reviwer found the crevice tool to be incredibly handy and manouverable when trying to reach hard-to-clean places such as floorboards and the point that her stairs met.
  • Upholstery tool
    • Our reviwer tested this by vacuuming spread porridge oats over a (sacrifiical) chair. It cleaned the mess in seconds with very little spread.

Executive Summary: The Shark IZ251 is compact when folded and small enough when fully extended that it’s easy to manoeuvre. The numerous tools it features make cleaning just about any mess – from pet hair to upholstery – a breeze. In fact, our reviewer found this to be one of the best devices for cleaning pet hair, regardless of how fuzzy your critters may be.


While the battery leaves a bit to be desired, the Shark IZ251 is a fantastic choice for those who struggle with pet hair and flexibility issues. It will save your carpet, upholstery, and back – we guarantee it.

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About the Author Dale Richardson

Love doing DIY and renovating my house. When I'm not doing that or working on this website, I love cooking, playing computer games and playing/watching football.