The way dishwasher tablets are sold is one of the most confusing areas of the store.
Value impacts: Price inflation, Shrinkflation, Range variation, Promotion variance
What matters: Price per tablet, does it clean your dishes?
What to look for: Promotions, Bulk discount, Value brands
Every superlative imaginable is given to dishwasher tablets from ultra clean to lemon sparkle and after all who hasn't been dazzled in the Produce aisle by the mirror like gleam of the lemon display!
To sell dishwasher tablets the marketing focusses on technical capabilities over and above washing dishes themselves. Modern tablets claim to leave your machine clean and protect your glasses and more. This amount of choice diversifies the range, building in confusion and clouding your value judgement. The additional functionality also comes at a cost, increasing the price; whilst often reducing the number of tablets per pack.
It is unlikely that a supermarket will sell you a dishwasher tablet that does not clean your dishes, so the best thing is to work out which attributes you really need and then buy the lowest cost tablet that meets that need. You only use one tablet per wash, so the best calculation I can see is the cost per tablet. As you work your way up the level of technical add-ons that you want, you will be conscious of how much extra each additional function costs and so be better informed.
Dishwasher tablets are susceptible to shrinkflation. Typically the number of tablets per box/sachet was writ large as a selling point, but the print is becoming smaller as we start to see fewer tablets per pouch and weird number combinations like 59 tablets appear.
Supermarket own label brands can offer significant savings with similar performance to the leading brands. Within the big four supermarket brands like Sainsbury's Tesco, Morrison Asda, there are also sub brands. The Sainsbury's House 24/7 or Asda Essentials for example can be priced as low as 4 pence per tablet but still work sufficiently well to clean most dishes.
Promotions distort the value perception too as a single brand might be promoted two different ways with different values per tablet and that may not follow the principle that buying in bulk guarantees a cheaper price. Promotions need evaluating to the cost per tablet too as larger non promoted items may still be cheaper with similar performance.
Buying bulk online can also lead to better deals. Below are lines available on Amazon, prices were correct at time of publication, but may change. Click on an image to buy through Amazon. (Sponsored links).
In summary the more you research the cost per tablet against the performance claims, the better chance you have of getting best value.
Disclaimer: I receive a small affiliate commission on lines bought through these links to support my costs and time involved. I am not sponsored by any company directly