Abstract: Presented herein is a modular backpack comprising a front module and a back module, with the front module releasably attached to the back module via a connection between an attachment element of the front module and an attachment element of the back module. The modular backpack system can include any number of center modules positioned between the front module and the back module and releasably attached to both the front and back modules. To be a large capacity backpack, the modular backpack system can include a back module, the appropriate number of center modules, and a front module. To be a small capacity backpack, the modular backpack system can simply include a front module with a number of pockets and a back module. Accordingly, the modular backpack system thus enables the user to easily and quickly customize their backpack as needed based on the occasion.