The Quran explicitly permits a traveller to break the fast and make up the missed days later (2:185), the same concession given to the sick. Scholars have debated the exact distance and duration that qualifies as travel for this purpose, since neither the Quran nor the Sunnah fixes a precise mileage. Most classical jurists set a rough threshold, commonly cited as around 80–90 km, roughly a day and night's journey by the standards of the time, though contemporary scholars differ on how to translate that into modern travel by car or plane, and some argue the key factor is genuine hardship and being outside one's home locality rather than a strict number. The concession applies once a person has actually left their town, not merely while planning to travel, and generally continues until they return home or settle somewhere for an extended stay, though opinions vary on how many days of stay ends 'traveller' status. It is a permission, not an obligation — the Prophet's own companions differed on whether fasting or breaking the fast while travelling was preferable, and reports describe him doing both on different journeys depending on the difficulty involved.
Q&A · Fasting
Is a traveller allowed to break the fast, and does it matter how far or long the trip is?
References
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.