Quick answer
Buy a protein shake for most of your protein and keep bars for the days you cannot mix one. On the prices we track, Protein Works Whey Protein 360 Black costs 24p per 10g of protein on its OnTap subscription price, while the Myprotein Layered Bar costs 92p per 10g, so a bar is nearly four times the cost per gram. A bar wins on convenience, because it needs no shaker, no water and no prep, and our best protein bars in the UK guide shows which bar to pick when you do want one.
A protein shake is the cheaper way to buy protein, and a bar is the easier one to carry, so the right choice depends on which of those you need more. On the figures we track, Protein Works Whey Protein 360 Black costs 24p per 10g of protein on its OnTap subscription price, against 92p for the Myprotein Layered Bar, so the bar is nearly four times the cost per gram. This guide sets out the costs, the calories and the times when each makes sense, and it hands the bar choice back to our best protein bars in the UK guide.
How much does a shake cost compared with a bar?
Protein Works Whey Protein 360 Black costs 60p per 25g of protein in the 4.8kg bag at £68.49, which is its OnTap subscription price. That works out at 24p per 10g of protein. OnTap is a subscription discount, about 15% below the one-off price, so a single tub costs more per gram than this figure.
Myprotein Layered Bar costs £1.83 a bar in a box of 12 on myprotein.com, which is 92p per 10g of protein for 20g a bar. Myprotein Impact Bar costs £1.92 a bar in the same box size, or 96p per 10g of protein. Prozis Melty Low Sugar Protein Bar costs £1.83 a bar with code WHEYWISE, or 85p per 10g of protein for its 21.6g, and £2.03 without the code.
| Option | Protein | Price basis | Per 10g of protein |
|---|---|---|---|
| Protein Works Whey Protein 360 Black, scoops with water | 25g | 60p per 25g, OnTap price (4.8kg for £68.49) | 24p |
| Protein Works The Big Little Bar | 10g | £1.00 a bar, box of 20 | £1.00 |
| Prozis Melty Low Sugar Protein Bar, with WHEYWISE | 21.6g | £1.83 a bar, box of 10 | 85p |
| Myprotein Layered Bar, Triple Chocolate Fudge | 20g | £1.83 a bar, box of 12 | 92p |
| Myprotein Impact Bar, Fudge Brownie | 20g | £1.92 a bar, box of 12 | 96p |
Whey Protein 360 Black from Protein Works' feed on 19 October 2026, at the OnTap subscription price. The Big Little Bar from theproteinworks.com on 3 October 2026. Prozis and Myprotein bars are from their own sites on 14 October 2026; per 10g is the box price divided by the protein per serving.
Cheapest per gram of protein in this comparison
Protein Works Whey Protein 360 Black
2.4kg bag
Protein Works' Whey Protein 360 Black: 60p per 25g of protein on its OnTap subscription price, the lowest cost per gram of the options here.
or compare all UK prices →Cheapest per gram of protein in this comparison
Protein Works Whey Protein 360 Black
2.4kg bagPros
- + 24p per 10g of protein on the OnTap price
- + Chocolate Silk has 59g of protein per 100g on its label
- + Mixes with water in a shaker, with no bar packaging to carry
Cons
- – 24p is the OnTap subscription price, so a one-off tub costs more
- – Needs a shaker and water, so it is less convenient out and about
●Nutrition per scoop · 17.7g protein in 30g▼
Protein makes up 59%
of this 30g scoop · 109 kcal total
Over ten 20g servings the gap is easy to see. Ten Myprotein Layered Bars at £1.83 each come to £18.30 for 200g of protein, while the same 200g from Whey Protein 360 Black at the OnTap price is about £4.80, or twenty lots of 24p. Those are arithmetic on the figures above, not a quote, and a single tub bought one-off costs more than the subscription figure.
How do the calories compare?
A 20g bar is around 210 kcal in our examples: the Myprotein Layered Triple Chocolate Fudge gives 20g of protein in 212 kcal, and the Impact Fudge Brownie gives 20g in 233 kcal. Before you compare, check the label on each product, because the protein-per-calorie figure is the useful one. Our guide on how to read a protein bar label shows how to work that out from any panel.
Compare per 10g of protein rather than per portion, because a bar and a shake rarely deliver the same grams in one serving. The table above does that, so the cost comparison and the calorie comparison can be read on the same basis. Either way, the ISSN position stand on protein and exercise puts a useful serving at 20g to 40g of protein, so a 20g bar counts as a full serving.
We don't have a calorie figure for Whey Protein 360 Black in our data, so we won't put one on it. A shake made with water and one made with milk give different totals, because milk adds calories of its own, so say which you use when you compare.
Which is more convenient after training?
A bar wins on convenience: it needs no shaker, no water and no preparation, so it fits a gym bag or a coat pocket. That makes it the easy choice when you have no kitchen nearby, such as on a train or straight after a late session.
A shake wins when you train at home or can make it the moment you get back. For when a bar helps most in the day, including after training, read when to eat a protein bar.
When does each one make sense?
Buy a shake if your priority is cost per gram: it is the cheapest protein in this comparison, and you control the portion with the scoop. Bars also suit a fixed snack size, and some people prefer a bar's texture to a drink.
A shake lets you adjust the amount with the scoop, while a bar is one fixed portion, so the shake suits days when you need more or less protein. A shaker also has to be washed afterwards, a small chore that adds up in a busy week.
Buy a bar when you need protein with no prep, such as between meals at work or on a day out, and the Myprotein Layered Bar gives 20g in one piece. Some bars also use sweeteners that some people find hard to digest, which our guide to why protein bars taste artificial covers. If you eat bars most days, check how many is sensible in can you eat protein bars every day.
20g of protein with nothing to mix
Myprotein Layered Protein Bar
Myprotein's six-layer bar. Triple Chocolate Fudge gives 20g of protein in 212 kcal with 1.9g of sugar, sweetened with maltitol and no sucralose.
Myprotein's six-layer bar. Triple Chocolate Fudge gives 20g of protein in 212 kcal with 1.9g of sugar, sweetened with maltitol and no sucralose.
Pros
- + 20g of protein in 212 kcal
- + 1.9g of sugar per bar
- + Rated 4.6 out of 5 from 1,113 reviews on myprotein.com
Cons
- – Uses palm and palm kernel oil
- – Hydrolysed beef gelatin is one of its protein sources, so it isn't vegetarian
- – Sweetened with maltitol, which can upset some stomachs
How do you split bars and shakes across a week?
Many people use both: a shake at home on training days, and a bar on the days when they are out from morning until night. That keeps the cost down without giving up convenience when you need it.
If you do that, count bars and shakes in the same daily total, so you can see how many sweetened bars sit on top of the shake. A bar a day plus a shake is a simple pattern, and our guide on whether you can eat protein bars every day covers how far that goes.
Which should you choose for most weeks?
Choose a shake as your main source of protein if you can make it, because it is the cheapest way to buy protein, and keep bars for the days you can't. For a bar to snack on, Protein Works The Big Little Bar is the lightest option, at £1.00 a bar. For more protein from one bar, the Myprotein Layered Bar gives 20g.
For the bar you should buy, and how the bars compare on protein, sugar and sweeteners, go to our best protein bars in the UK guide. For the daily total and whether bars fit it, see can you eat protein bars every day.
Frequently asked questions
Is a protein bar or a protein shake better?
For cost, the shake. Protein Works Whey Protein 360 Black is 24p per 10g of protein on its OnTap price, against 92p per 10g for the Myprotein Layered Bar in a box of 12. For convenience, the bar, because it needs no shaker or water. Choose the one you will actually use.
Is a protein shake cheaper than a protein bar per gram?
Yes, on the prices we track. The OnTap price for Whey Protein 360 Black is a subscription price, and its one-off price is about 15% higher, so a single tub costs more per gram than the subscription figure.
Do protein bars have more calories than shakes?
A 20g bar is around 210 kcal in our examples, such as the Layered Triple Chocolate Fudge at 212 kcal. We don't have a calorie figure for Whey Protein 360 Black, so read the scoop size and kcal on the tub before comparing.
How much protein should I have after training?
The ISSN position stand puts a serving at 20g to 40g of protein, spread through the day. A 20g bar or a 20g scoop counts as one serving, and the total across the day matters more than the exact hour.
Can I just carry bars instead of a shaker?
Yes. A bar needs no water or shaker, so it is the easier option away from home. It costs more per gram of protein than a shake, so it suits the odd snack better than a daily habit.
