From Longman Dictionary of Contemporary Englishreckon without somebody/something phrasal verb British EnglishTHINK ABOUTif you are reckoning without something, you do not expect it and are not prepared for it They doubted that Fiona could finish the course, but they reckoned without her determination. → reckon→ See Verb table
Examples from the Corpus
reckon without • But they'd reckoned without planning laws, and may have to move.• But they had reckoned without Sister Murphy.• I reckoned without that dummy Ryder.• He had reckoned without the effect of his anger and his appearance on the man, who trembled.• If so, they may have reckoned without the fleet, which provided the Roman army with its mobility.• But she reckoned without the impact her daughter was to make.• But he reckoned without the propensity for panic in his rivals, who needed only par to rule Brooks out.• But they reckoned without their hectic schedule. 