CalcSpan - Date calculators with rules attached

CalcSpan is a free collection of 183 date, deadline, and cycle calculators for people who need more than a bare number. Each result explains what was counted, what was excluded, and which assumptions shaped the answer. Visitors can search by question and calculate without creating an account. Inputs stay in the browser. The collection covers date differences, business days, sleep timing, deadlines, life milestones, and specialized planning windows, with sources and review dates shown where rules matter.