Shoppers have more money-off deals to choose between than ever before but the size of the savings is shrinking fast, according to exclusive research carried out for The Grocer.

The number of promotions in supermarket featured space, such as gondola ends and pallets, hit a high of 8,291 this week, 1,065 more than this time last year [4w/e 21 August]. But data from promotion tracker Assosia reveals the price of more choice is smaller savings, especially on own label.

The average discount on featured deals has dropped a hefty 2.5 percentage points year-on-year, down from 34.3% to 31.8%. But on own-label promotions, the drop is much larger. Last August, a typical own-label money-off deal offered a 33.5% saving. This year, that dropped a full 6.5 percentage points to 27%.

Savings on branded lines remained high despite a similarly large rise in total offers. Brand deals offered a typical reduction of 33.6%, exactly the same as this time last year. However, month-on-month there has been a 0.9 percentage point fall in typical saving.

"Shoppers have a huge range of deals to choose from at the moment, and so are more likely to find offers they like," said Assosia MD Kay Staniland. "But because there are so many deals, retailers can't afford to keep discounts at previous levels, so the saving has dropped in cash and percentage terms.

"Because much of the cost of branded promotions is borne by manufacturers, branded savings are staying more or less constant, but on own-label the drop is really substantial. Shoppers are more likely to find the promotions they want, but the bargains generally aren't quite as good as a year ago."

Discounts fell most sharply at Tesco, where the typical saving in 2009 was 29% less than last year. Savings fell at all of the big four retailers, but least of all at Sainsbury's, where the typical discount was just 4.5% less than last year. Sainsbury's was also the retailer offering the highest savings on own-label products, with a typical 30.4% .