reckon on (something)
To consider or anticipate something as a factor in some decision, situation, or outcome. I thought we'd have enough money for a deposit on a house, but we hadn't reckoned on needing to pay for Sophie's trip to the emergency room. They reckoned on spending about $2,000 on flights and hotels in Europe.
reckon on
v. To expect and take something into account; bargain on something: The farmers hadn't reckoned on an early frost. Reckon on spending $250 for a hotel room in New York.