Period Calculator was built with a single objective: to provide individuals worldwide with a highly accurate, entirely private, and seamless method for tracking their menstrual cycles. In an era where digital privacy is a luxury, we built a platform that allows you to calculate fertility windows and period timelines without sacrificing your personal data to large databases.
To ensure high trustworthiness and reliability, our calculators utilize widely accepted medical standard formulas to derive estimates for luteal phases, ovulation dates, and safe days. While every person is biologically unique, these algorithmic baselines provide excellent starting points for cycle awareness. We constantly monitor scientific literature to ensure our baseline calculations match the latest health advisory guidelines.
We strongly believe that reproductive health data belongs exclusively to you. The Period Calculator processes 100% of its functions locally on your device using Client-Side JavaScript. You do not need to register an account, and we do not maintain tracking servers for your inputs. What you type stays on your phone.
Period Calculator