Hi guys quick question

Had a few various decorating guys come quote me for a paint job and I just got an email back about my living room and he said

"According to the specs, coverage is 14m2/L so for two coats in your lounge you’ll just about get away with 5L which will probably cost you at least £100."

I've just bought 5 litres of little greene last week do I need to buy another small 2.5 litre can or is the coverage good with little greene? Professional opinions welcome

(Am autistic so sometimes I don't understand things like meter squared all this, makes wanting to do stuff difficult and I've never painted before, just after some thoughts because the 5 litre I bought cost £110, funnily enough 🤣)