Whether 30-inch luggage is considered "oversized" depends on the specific airline's measurement criteria, but it frequently borders on the limit for standard checked baggage. Most major airlines worldwide (such as United, Emirates, and Air India) use a "linear inch" limit of 62 inches (158 cm), calculated by adding the Length + Width + Height. A typical 30-inch suitcase (e.g., 30" x 20" x 12") adds up to exactly 62 linear inches, meaning it is just at the threshold. However, if the wheels, handles, or external pockets push those dimensions even slightly higher, you may be charged an "Oversized Baggage" fee, which in 2026 can range from $100 to $200 per flight. For domestic carriers like IndiGo, the rules are often stricter, and bags exceeding the 158 cm total are subject to additional surcharges. It is also important to remember that larger bags are more likely to exceed the weight limit (typically 50 lbs or 23 kg). For any traveler in 2026, the safest strategy is to use a 28-inch suitcase to ensure you stay comfortably within the standard dimensions and avoid the "at-the-counter" stress of potentially being flagged for a massive oversized luggage penalty.