How to measure sleeve: we can also measure your sleeve length from the centre back of your neck to the end of your shoulder at the top of your arm; then we measure sleeve length accurately; you'll need a flexible tape measure and someone to assist you with the most precise results. Here's a step-by-step guide: prepare the individual. If we are measuring for someone else, ensure they're standing comfortably with their arm slightly bent at the elbow and relaxed at their side.