Changing eating habits and a preference for packed lunches are said by some authorities to be responsible for the drop.
Around 314,000 pupils took lunch on the school meals census day in November. Forty-seven per cent were in primary and 43 per cent in secondary. School dinners are most popular in Shetland, where four out of five pupils tuck in at the lunch hall.
Twenty-two per cent of nursery and primary pupils and 17 per cent of secondary pupils are entitled to free meals, marginally higher than in the previous four years.
Glasgow, with high levels of poverty, outstrips all other authorities. Just over 46 per cent of primary pupils and 41.6 per cent of secondary pupils are entitled to free meals. In Aberdeenshire, only 7.1 per cent of primary and 3.8 per cent of secondary pupils are entitled to free lunches because of family poverty.