Who Created The Calendar We Use Today. By the time he reformed the julian calendar in 1582 (using the observations of christopher clavius and johannes kepler), it had drifted 10 days off course. The romans developed this model and it was julius caesar, who oversaw the formation of the julian calendar and is acclaimed for putting in place the foundations of the calendar we use.

By the time he reformed the julian calendar in 1582 (using the observations of christopher clavius and johannes kepler), it had drifted 10 days off course. Caesar decided it was time to reform the roman calendar.