The Tower Vortx 4.2L costs at most 12.3p for a 20-minute cook at the October 2026 price cap. The Ninja Air Fryer Pro 4.7L (AF140UK) costs at most 15.4p on the 1,750W rating Ninja prints in its own manual. The Tower was also £29.01 cheaper on Amazon UK on 5 November 2026, so the Ninja never earns its higher price back. It has no pence-back point at all.
One more thing to know before you compare them anywhere else. Amazon's listing for the Ninja says 2,000W. Ninja's instruction manual and Ninja's own UK shop both say 1,750W. At Amazon's figure the Ninja would cost 17.5p a cook, so any running cost worked from the listing overstates it by about 2.2p.
The verdict, 5 November 2026
- Rated power: 1,400W for the Tower, 1,750W for the Ninja on Ninja's own figure. A 20-minute cook at full power costs 12.3p and 15.4p at 26.32p per kWh.
- Over a year of five cooks a week the ceiling is £31.93 for the Tower and £39.92 for the Ninja.
- The Tower is cheaper to buy and cheaper to run, so the Ninja has no pence-back point. Over three years at five cooks a week the Tower costs £52.96 less in total.
- The Ninja's extra half litre of drawer costs £29.01, which works out at £58.02 per extra litre.
- The Tower's guarantee runs three years if you register it, the Ninja's two. Per guaranteed year that is £16.66 against £39.50.
- The Ninja's Amazon listing gives its power as 2,000W and its warranty field reads "No warranty". Ninja's manual and shop say 1,750W and two years on registration.
| Tower Vortx 4.2L (T17147) | Ninja Air Fryer Pro 4.7L (AF140UK) | |
|---|---|---|
| Rated power | 1,400W | 1,750W (Ninja manual and shop); 2,000W on the Amazon listing |
| 20-minute cook at full power | 12.3p | 15.4p |
| A year, 260 cooks | £31.93 | £39.92 |
| Running cost per litre of drawer, per cook | 2.9p | 3.3p |
| Drawer | 4.2 L, one basket | 4.7 L, one drawer |
| Listed size, W × D × H | 34.6 × 28.5 × 28.4 cm | 28.5 × 36 × 26.5 cm |
| Who the listing says it feeds | "the entire family" | "up to 2 people" |
| Guarantee | 1 year, plus 2 more if registered online | 2 years if registered within 28 days |
| Price, 5 Nov 2026 | £49.99 | £79.00 |
| Total over three years, 260 cooks a year | £145.79 | £198.76 |
Prices and specs last checked by Look Into on 5 November 2026 · next check 1 January 2027 · how we picked
Why the Ninja has no pence-back point
On most of our head-to-heads the dearer machine is the cheaper one to run, and the question is how many uses it takes to earn its price back. Here the dearer machine is also the one that uses more power. The Ninja costs 3.07p more on each 20-minute cook and £29.01 more to buy, so the gap only ever widens.
| Cook length | Tower | Ninja | Ninja costs more by |
|---|---|---|---|
| 15 minutes | 9.2p | 11.5p | 2.3p |
| 20 minutes | 12.3p | 15.4p | 3.1p |
| 30 minutes | 18.4p | 23.0p | 4.6p |
These are ceilings. Both elements switch off once the drawer reaches temperature and back on as it cools, so real cooks cost less. Neither maker publishes a measured kWh for a cook, so the rated power is the only number either gives you to work from.
The 250 watts that went missing
Amazon's listing for the AF140UK says 2,000W in its bullets and in its technical details. Ninja's own instruction manual, on its UK support site, prints "Watts: 1750W". Ninja's UK shop lists 1,750 watts on the same product page as the price. We have used Ninja's figure, because it is the maker's and it appears in the document that comes in the box.
The difference matters if you are comparing fryers on running cost. Worked from the listing, the Ninja would cost 17.5p a cook and £45.62 a year at five cooks a week, about £5.70 a year more than Ninja's own rating gives. Our own air fryer guide used the listing's 2,000W until today and has been corrected.
The bigger drawer claims the smaller household
Tower's listing says its 4.2-litre basket makes enough food for the entire family. Ninja's listing says its 4.7-litre drawer is for up to two people, and that it takes a whole 1kg chicken or 500g of chips. The fryer with the bigger drawer makes the more modest claim. Ninja's is the only one of the two that says what fits, so it is the only one you can check against your own cooking.
Shape matters as much as litres. The Tower is 34.6 cm wide and 28.5 cm deep. The Ninja is 6.1 cm narrower but 7.5 cm deeper, at 28.5 cm by 36 cm. On a shallow worktop under wall cupboards the Tower is the easier fit; in a narrow gap between a kettle and a toaster, the Ninja is.
What the guarantees cost per year
Tower gives one year as standard and two more if you register the fryer online, three in total. Ninja gives two years if you register within 28 days of purchase. Divide each price on 5 November by the years covered and the Tower costs £16.66 per guaranteed year against £39.50 for the Ninja. Register either one the day it arrives, because neither gets its full term otherwise. The Ninja's Amazon listing has a warranty field that reads "No warranty", which contradicts Ninja's own terms.
Which one to buy
Buy the Tower if you want the cheaper fryer to buy, to run and to keep covered. On these figures it wins on all three, and over three years at five cooks a week it costs £52.96 less in total.
Buy the Ninja if you specifically want to roast a whole 1kg chicken in a single drawer, or if your worktop is narrow and deep. Those are the only reasons on the page, and you pay about £29 up front and about £8 a year for them.
How we worked it out
| Item | What we did |
|---|---|
| Electricity rate | 26.32p per kWh, the Ofgem cap for 1 October to 31 December 2026, direct debit, Great Britain average. Standing charge left out. |
| Power | Tower: 1,400W, the same on the Amazon UK listing and Tower's retailers. Ninja: 1,750W from Ninja's AF140UK instruction manual and Ninja's UK shop; the Amazon UK listing's 2,000W is shown for comparison. No listing publishes a measured kWh for a cook. |
| Cost per cook | Rated watts for 20 minutes at 26.32p per kWh. The element cycles off once the fryer is up to temperature, so this is the most a 20-minute cook can cost. |
| A year | 260 cooks, five a week. |
| Prices | Amazon UK, read 5 November 2026: Tower £49.99, Ninja £79.00, both sold by Amazon. They move often, especially in late November. |
| Three-year total | Price plus three years of 260 cooks at the current cap. It ignores future cap changes, which move both fryers by the same proportion. |
| Cost per guaranteed year | Price divided by the guarantee years available on registration: £49.99 ÷ 3 and £79.00 ÷ 2. |
What this comparison could not check
- We have not cooked in either fryer. How evenly each one crisps needs the machine in your hands.
- What a real cook uses. No listing publishes a measured kWh, so every cost here is rated power for the whole cook, the most it could cost.
- Whether a 1kg chicken fits the Tower. Tower does not say what its basket takes.
- Why the Ninja listing says 2,000W. We have reported the disagreement rather than guess at it.
Today's Amazon prices
These boxes pull Amazon's live price when you load the page, so they can differ from the figures above, which were read on 5 November 2026. Look Into earns a commission if you buy through them; it does not change the verdict.
As an Amazon Associate, Look Into earns from qualifying purchases. Product prices and availability are accurate as of 6 November 2026 10:08 am and are subject to change.
As an Amazon Associate, Look Into earns from qualifying purchases. Product prices and availability are accurate as of 6 November 2026 8:41 am and are subject to change.
The two fryers
Tower Vortx 4.2L (T17147)
At most 12.3p for a 20-minute cook at the October 2026 cap, on its 1,400W rating. One 4.2-litre basket, eight presets and a shake reminder. Three years of guarantee if you register it.
The catch: Tower does not say what fits in the basket, and it is the wider and shallower of the two at 34.6 cm across.
Ninja Air Fryer Pro 4.7L (AF140UK)
At most 15.4p for a 20-minute cook on the 1,750W rating in Ninja's manual. One 4.7-litre drawer that Ninja says takes a whole 1kg chicken. Two years of guarantee if registered within 28 days.
The catch: dearer to buy and to run than the Tower, so it never pays back, and its Amazon listing overstates its power by 250W.
Look Into earns a commission on qualifying purchases made through the Amazon links above, at no extra cost to you. It never changes the arithmetic.
Common questions
Is the Tower Vortx 4.2L cheaper to run than the Ninja AF140UK?
Yes. Tower rates the Vortx 4.2L at 1,400W and Ninja rates the AF140UK at 1,750W in its manual, so a 20-minute cook at full power costs at most 12.3p against 15.4p at the October 2026 cap of 26.32p per kWh. Over 260 cooks a year that is about £8.
Is the Ninja AF140UK 1,750W or 2,000W?
Ninja's instruction manual and Ninja's UK shop both give 1,750W. The Amazon UK listing says 2,000W. We use the maker's figure.
Is the Ninja AF140UK worth the extra money over the Tower Vortx?
Not on cost. On 5 November 2026 it cost £29.01 more on Amazon UK and it costs more on every cook, so it never earns the difference back. Buy it only if you want a drawer that takes a whole 1kg chicken or a narrower, deeper body.
Which has the longer guarantee, Tower or Ninja?
Tower: one year, plus two more if you register online, three in total. Ninja: two years if you register within 28 days of purchase.
Compare more
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- Ninja AF300UK vs AF400UK: the bigger one costs more per cook and less per litre of drawer
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Sources
- Ofgem, energy price cap unit rates and standing charges (1 October to 31 December 2026)
- Ninja, Air Fryer 4.7l Pro AF140UK instructions ("Watts: 1750W"), read 5 November 2026
- Ninja UK shop, Air Fryer PRO 4.7L AF140UK (1,750 watts, 2-year warranty), read 5 November 2026
- Amazon UK listings for the Tower Vortx 4.2L (B0CTS3W442) and Ninja Air Fryer Pro 4.7L AF140UK (B0CYH88L3D): power, capacity, size, guarantee wording and price, read 5 November 2026
- Look Into, best air fryers UK 2026