My chest is 35" and I still have trouble getting my medium on. You + small = no chance. You want a medium, and if you're actually in store there'd be no harm in trying the size above either. And yeah what he said above is way off. All Superdry clothing is smaller than usual UK sizes because it's modelled on Japanese sizes (and don't call me racist, but generally speaking the Japanese are a bit smaller than Caucasians). Superdry isn't international but to fit in with their 'Japanese' stuff they use Japanese sizing. Anyway that's why Superdry sizes start at small and go all the way up to extra extra large in the UK, because they have to try and accommodate for the larger sizes of Caucasians.