Interest plays a vital and increasing role in international arbitration proceedings, with almost every case having an element of interest involved. However, until now, the topic has received very little attention, meaning that arbitrators have had very little concrete foundation on which to judge decisions on interest awards. This book is the first authoritative guidance to address this, providing a uniform approach to the awarding of interest in international arbitration. The book aligns arbitrators' decisions with standard commercial practice, offering a practical and logical approach to how interest should be awarded. It sets out traditional approaches that arbitrators have followed in the past, such as using conflict of law to apply a statutory rate from a given law, or awarding instead a subjectively ‘reasonable’ rate, and examines how these inconsistent approaches have resulted in a variety of awards and decisions. The book uses this analysis as a basis for a uniform approach to the issue: granting compound interest at appropriate rates unless constrained by truly mandatory law. It sets out the calculation method, explores the benefits and limitations, and presents a thorough argument for the movement toward a uniform approach to interest awards.