The interior footpad is too narrow for my custom orthotics. The footpad is narrower than customary in this size shoe. I don't have the measurement now as I returned the shoe. I usually wear a medium width but even the wide here is too narrow. I have some older Merrell shoes I really like. I could get an orthotic for this shoe but it costs 3x the price of the shoe. I suspect the footpad may be narrow to increase the slope of the side to provide more arch support, but this is speculation.