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Why This Guide Is Different (Tested for Real UK Homes)
- We test in real UK rooms — bedrooms, flats, open-plan spaces — not labs
- Every recommendation is matched to room size, dust levels, and budget
- We only recommend products we'd use in our own homes
- Prices, availability, and picks updated monthly for the UK market
Quick Picks
Blueair Blue Pure 511i Max
19dB on its lowest setting and 43m² coverage — tracked at £79.99
Xiaomi Mi Air Purifier 4 Compact
App control and auto mode at 27m² coverage — tracked at £88.97
Levoit HEPA Bedroom Purifier
Dual HEPA filtration for a single bedroom or desk — tracked at £49.99
As an Amazon Associate, AirDaddy earns from qualifying purchases. All prices in GBP, recorded from Amazon UK between 24 and 31 August 2026.
Best Choice for Most People
- →If you want the best all-round purifier under £100 → Blueair Blue Pure 511i Max (£79.99)
- →If you want app control for the least money → Xiaomi Mi Air Purifier 4 Compact (£88.97)
- →If you want to spend as little as possible → Levoit HEPA Bedroom Purifier (£49.99)
- →If you want to measure the air before you buy → Temtop S1 monitor (£29.99)
Until this summer, the honest answer to "what is the best air purifier under £100 in the UK?" was: not much. The sub-£100 shelf was dominated by ioniser-style units with no real filter, and by "HEPA-type" media that does not meet the H13 standard. That has changed. Our Amazon UK price tracking now records several genuine HEPA units at or below £100, including one with app control and auto mode.
This guide is built entirely on those recorded prices. Every GBP figure on this page is a price our tracker logged from Amazon UK on the date shown, not a manufacturer RRP and not an estimate. Amazon prices move constantly, so treat each figure as the price at the moment it was recorded and check the live price before you buy.
One correction, published openly: this guide previously led with the Levoit Core 300S at £99.99. That price came from a superseded Amazon listing rather than the Core 300S we recommend, which is verified at £149.99. It has been removed from this page and now sits in our best air purifier under £200 guide, where it belongs. The full UK buying guide covers every price point.
Our Top Picks
Key Factors to Consider
True HEPA H13 is the only filtration worth buying at this price
Under £100 the single biggest risk is buying something that does not actually filter. Look for the words "True HEPA H13" or an explicit 99.97% at 0.3 microns claim. "HEPA-type", "HEPA-style" and "HEPA-like" are marketing terms with no standard behind them, and at this price they are common.
Avoid anything sold primarily as an ioniser or ozone generator. An ioniser charges particles so they stick to nearby surfaces rather than removing them from the room, and ozone-producing units are actively unhelpful in a sealed UK bedroom. Every unit on this page uses physical filtration and is ozone-free. Our HEPA filters explained article covers the grading system in full.
Filter cost matters more than purchase price under £100
A £50 purifier with £35 filters twice a year costs more over three years than a £100 purifier with a £20 annual filter. Cheap purifiers are often sold at a loss and recovered on consumables, so the filter price is the number to check before you check the sticker price.
Levoit is the strongest brand in this range on consumables — replacement filters are widely stocked by UK sellers and typically fall in the £20–£30 band. Our Filter Club sends a reminder when a replacement is due, which matters because a clogged filter quietly turns a working purifier into an expensive fan.
Match coverage to the room, not to the budget
Coverage figures under £100 range from 15m² to 43m² across the units here. A 15m² unit in a 30m² living room will run flat out and still lose. Measure the room, and if you are between sizes, size up rather than down — a larger unit on a low speed is quieter and more effective than a small one at maximum.
As a rule of thumb for UK housing: a typical double bedroom is 12–16m², a box room 7–10m², and a terraced-house living room 18–25m². Our room size guide works through the CADR maths if you want to be precise.
Noise decides whether the purifier actually runs
The most common failure mode for a bedroom purifier is that its owner turns it off. A unit that only reaches its rated clean air delivery at a speed you cannot sleep through is, in practice, a slower purifier. Manufacturer decibel figures are usually lowest-speed chamber measurements, so treat them as a ranking tool rather than an absolute.
Of the units here, Blueair states 19dB on the 511i Max's lowest setting and Levoit states 28dB on its compact bedroom unit — both quiet enough for most sleepers. Our quietest air purifiers guide covers this in more depth, and the AirDaddy Labs noise testing protocol explains how we measure it.
Running cost is small, but it is not nothing
These are 10W to 40W devices. Run twelve hours a day on a low speed, most of them cost single-digit pounds a year in electricity at the prevailing Ofgem unit rate. The dominant cost is filters, which is why the annual figures quoted below are mostly filter cost.
Across this group we would budget £25–£55 a year in total ownership cost. That is meaningfully lower than the £60–£90 typical of the £200–£400 tier, largely because smaller filters cost less.
Sub-£100 purifiers — tracked UK prices and running costs (recorded 24–31 August 2026)
| Product | Tracked price (GBP) | Date recorded | Coverage | Stated noise (low) | Annual running cost |
|---|---|---|---|---|---|
| Xiaomi Mi Air Purifier 4 Compact | £88.97 | 25 August 2026 | Up to 27m² | 27dB | ~£45–£55 |
| Blueair Blue Pure 511i Max | £79.99 | 31 August 2026 | Up to 43m² | 19dB | ~£55–£65 |
| Levoit HEPA Bedroom Purifier (Quiet Sleep) | £49.99 | 24 August 2026 | Up to 15m² | 28dB | ~£25–£35 |
| Temtop S1 air quality monitor | £29.99 | 31 August 2026 | n/a (monitor) | Silent | Negligible |
Prices are the figures recorded by AirDaddy's Amazon UK price tracking on the dates shown, in GBP. Noise and coverage are manufacturer-stated. Amazon prices change frequently — check the live price before buying.
Is a £100 air purifier actually worth buying?
Yes, provided it uses true HEPA H13 filtration and is sized for the room. The filtration standard does not change with price: an H13 filter captures 99.97% of particles at 0.3 microns whether it sits in an £80 Blueair or a £399.99 Dyson. What you lose at the lower price is coverage, sensor accuracy, build materials and smart-home depth — not filtration quality.
What you should not buy at this price is an ioniser, an ozone generator, or anything described as "HEPA-type". Those are the products that give budget purifiers a bad reputation, and they are concentrated below £80.
What is the cheapest air purifier in the UK with a real HEPA filter?
In AirDaddy's tracked Amazon UK data for August 2026, the cheapest unit with genuine HEPA filtration that we recommend is the Levoit HEPA Air Purifier for Bedroom (Quiet Sleep Mode), recorded at £49.99 on 24 August 2026. It uses dual HEPA filtration rated at 99.97% down to 0.3 microns plus an activated carbon layer, and it is ozone-free.
Below that price point we have not found a unit that meets our filtration and safety bar. Cheaper listings are predominantly ionisers or unrated "HEPA-type" media.
How much does a sub-£100 air purifier cost to run per year in the UK?
Between roughly £25 and £65 a year, and most of that is filters rather than electricity. These units draw 10W to 40W; running one twelve hours a day on a low speed costs single-digit pounds a year at the prevailing Ofgem unit rate.
The Levoit bedroom unit is cheapest to own at roughly £25–£35 a year. The Xiaomi sits at roughly £45–£55. The Blueair 511i Max is the dearest of the group to keep running, at roughly £55–£65, because its filters cost more than Levoit's.
Can an air purifier under £100 help with hay fever or dust?
For pollen and household dust, yes — both are comfortably within the size range a HEPA H13 filter captures, and a correctly sized unit running continuously in a bedroom will lower the particle load you breathe overnight. Our hay fever guide and dust guide go into the specifics.
Two caveats. A purifier does not remove dust that has already settled on surfaces — you still have to clean. And it only treats the room it is in, with the door closed, so one unit will not cover a whole house.
Should I buy an air quality monitor as well?
It is optional, but it is the single cheapest way to find out whether a purifier is doing anything. Our tracker recorded the Temtop S1 at £29.99 on 31 August 2026, which makes a monitor plus the £49.99 Levoit a complete sub-£80 setup.
A monitor tells you your baseline PM2.5, shows the decay curve when the purifier runs, and stops you guessing. See our cheap air quality monitors guide for the alternatives.
Our Recommendations
Blueair Blue Pure 511i Max
Typical price: £79.99Blueair states 19dB on the lowest setting and never above 48dB at maximum, and the 511i Max covers up to 43m² — the largest coverage figure of anything we track under £100. Our tracker recorded it at £79.99 on 31 August 2026, down from £89.99 earlier in the month. HEPASilent combines mechanical and electrostatic filtration, so it moves more air for less fan noise than a purely mechanical unit of the same size.
- ✓ 19dB stated on lowest setting
- ✓ 43m² coverage — the widest here
- ✓ Blueair app with scheduling and filter tracking
- ✓ Tracked price fell £10 during August
- ✗ Blueair does not publish a CADR figure for this model
- ✗ Filters are dearer than Levoit equivalents
⚠️Prices can change frequently on Amazon.
💡Air purifiers only work properly if filters are replaced regularly. See our Filter Club for guidance.
Levoit HEPA Air Purifier for Bedroom (Quiet Sleep Mode)
Typical price: £49.99At the £49.99 our tracker recorded on 24 August 2026, this is the cheapest unit on the UK market we are willing to recommend. It is deliberately simple: three fan speeds on one button, no app, no sensor, ozone-free, dual HEPA filtration capturing 99.97% of particles down to 0.3 microns, plus activated carbon for odours. Coverage is only 15m², so treat it as a box-room, desk or nursery-corner unit rather than a whole-room solution.
- ✓ Lowest credible entry price we track
- ✓ Dual HEPA plus activated carbon
- ✓ ~£25–£35 a year to run — the cheapest here
- ✓ Ozone-free, no ioniser
- ✗ 15m² coverage only
- ✗ No app, sensor or auto mode
- ✗ Levoit does not publish a CADR for this model
⚠️Prices can change frequently on Amazon.
Want to catch this at the lowest price?
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What Size Air Purifier Do You Need?
| Room Size | Recommended |
|---|---|
| Up to 15m² (box room, nursery corner, desk) | Levoit HEPA Bedroom Purifier |
| 15–27m² (typical UK double bedroom) | Xiaomi Mi Air Purifier 4 Compact |
| 27–40m² (bedroom plus landing, small living room) | Blueair Blue Pure 511i Max |
| Up to 43m² (terraced living room) | Blueair Blue Pure 511i Max |
Comparison Table
| Product | Best For | Price | Rating | Noise | Coverage |
|---|---|---|---|---|---|
| Blueair Blue Pure 511i Max | Best Overall | Typical price: £79.99 | 4.4 | 19dB | 43m² |
| Xiaomi Mi Air Purifier 4 Compact | Best Smart Budget | Typical price: £88.97 | 4.5 | 27dB | 27m² |
| Levoit HEPA Bedroom Purifier (Quiet Sleep) | Best Budget | Typical price: £49.99 | 4.4 | 28dB | 15m² |
Who Should Buy This?
- →Choose the Blueair Blue Pure 511i Max if you want the widest coverage and the quietest unit under £100
- →Choose the Xiaomi Mi Air Purifier 4 Compact if you want app control and auto mode for the lowest possible price
- →Choose the Levoit HEPA Bedroom Purifier if you need a small unit for a box room, nursery corner or desk
Pros & Cons
Pros
- ✓ Genuine HEPA-grade filtration is now available well below £100 in the UK
- ✓ Annual running costs of £25–£55 — lower than any other tier
- ✓ Smart app control and scheduling available under £90
- ✓ Small footprint suits UK flats, box rooms and terraced bedrooms
Cons
- ✗ Coverage tops out at 43m² — not enough for open-plan spaces
- ✗ No unit at this price has a reliable numeric PM2.5 display
- ✗ The sub-£80 market is crowded with ionisers and unrated "HEPA-type" filters
- ✗ Prices at this level move quickly; a tracked price is not a guaranteed price
Frequently Asked Questions
Conclusion
For most UK households the answer under £100 is the Blueair Blue Pure 511i Max at the £79.99 we recorded on 31 August 2026 — the widest coverage here at 43m², a stated 19dB on its lowest setting, and app control.
If you want auto mode driven by an onboard sensor, the Xiaomi Mi Air Purifier 4 Compact at £88.97 is the smartest thing at this budget. If you simply want the least you can spend without buying something useless, the Levoit HEPA bedroom purifier at £49.99 is where that line sits.
Whichever you choose, size it to the room, put it where you sleep, and replace the filter on schedule. Those three decisions matter more than the difference between any two units on this page.
Don't Forget Your Filters
Air purifiers only work if the filters are replaced regularly. Most people forget — and end up breathing dirty air.
Join the Filter Club