🏛️ Roman Calendar Date Converter
The Romans didn't number days 1-31 — they counted backward, inclusively, from three fixed points in each month: the Kalends (the 1st), the Nones (the 5th, or 7th in March/May/July/October), and the Ides (the 13th, or 15th in those same four months). This tool converts either direction using the real ante-diem counting rule.
1. Gregorian → Roman
| Roman date | — |
|---|---|
| Classical-style abbreviation | — |
2. Roman → Gregorian
| Gregorian date | — |
|---|
The counting rule: Romans counted inclusively — both the reference day and the target day count toward "N". So the day right before the Ides is "2 days before the Ides" (pridie), not "1 day before". Days after the Ides count down toward the Kalends of the following month, not the current month.