The government recommends that free or added sugars shouldn't make up more than 5% of the energy (calories) you get from food and drink each day. That's a maximum of 30g of added sugar a day for adults, which is roughly seven sugar cubes.
Children should have less – no more than 19g a day for children aged 4 to 6 years old (5 sugar cubes), and no more than 24g (6 sugar cubes) for children aged 7 to 10 years old.

Read the NHS guidelines on sugar intake.