Four inputs: the model and its current market value, the condition grade (Flawless, Good, Average or Below Average), how long ago you bought it (under 4 months, 4-12, 12-18, 18-24 or over 24 months) and which accessories you still have (box, charger, battery, bill, bag, strap/caps/mounts, warranty card). The full explanation is on our
camera resale value page.