How break-even works
Out of every £1 you take (without VAT), your GP is what's left after ingredients. That's the money that pays your running costs. So divide your monthly running costs by your GP %.
Sales needed = running costs ÷ GP %
With £8,000 of running costs and a 68% GP, that's about £11,765 per month without VAT, or about £452 per opening day if you open six days per week.