Airline Checked-Baggage Size and Weight Limits Compared
Nearly every major US airline shares the same baseline checked-bag limit: 62 linear inches (length + width + height) and 50 lbs. Where airlines genuinely diverge is the fee once a bag exceeds that limit -- Delta charges $100 for a 51-70lb bag and $200 for 71-99lbs, while Frontier's single-tier overweight fee is a flat $129 covering the entire 51-99.99lb range, and oversize fees separately add $75-$200 more depending on carrier.
Checked-baggage policies read as though every airline sets its own rules from scratch, but the baseline is nearly identical across carriers -- it's what happens once a bag crosses that baseline where the sometimes-substantial differences actually show up.
The Shared Baseline Almost Every Airline Uses
Establishing this first matters, since it's genuinely consistent: the standard economy checked-bag allowance at most major US airlines -- American, Delta, United, and Southwest among them -- is 62 linear inches (length plus width plus height added together) and 50 lbs (23 kg) per bag. Premium cabins commonly allow a higher weight threshold; Delta's premium cabins, for instance, permit up to 70 lbs. Southwest's notable structural difference isn't the size limit itself but the free allowance: two checked bags included at no charge, a real point of differentiation from carriers that charge for a first or second checked bag by default.
A Comparison Table: Overweight Fees
| Airline | 51-70 lbs | 71-99.99 lbs |
|---|---|---|
| Delta | $100 | $200 |
| American | Comparable tiered structure -- a 70lb bag can run $200+ in overweight fees alone | Higher tier, similar range |
| Frontier | $129 flat (single tier covering the full 51-99.99lb range, effective for bookings from April 4, 2026) | Same $129 flat rate |
| Allegiant | $50 | $75 (71-99 lbs) |
| Breeze | $75 flat (covers any bag over weight or size limits, up to 99 lbs or 80 linear inches) | Same $75 flat rate |
The pattern worth noticing: legacy carriers (Delta, American) use a tiered structure where the fee roughly doubles at the second weight threshold, while several budget carriers (Frontier, Breeze) use a single flat fee across a wider weight range instead -- meaning a bag at 55 lbs and a bag at 95 lbs can cost identically on a budget carrier but very differently on a legacy one.
Oversize Fees Are a Separate Charge
This is a genuinely important distinction, since oversize and overweight are two different violations that can both apply to the same bag simultaneously. A bag exceeding the 62-linear-inch size limit incurs a separate oversize fee, typically ranging from $75 to $200 depending on the carrier, layered on top of any overweight fee already owed. American Airlines' own documented example makes this concrete: a 70-lb, 70-linear-inch bag -- both overweight and oversized -- can run $200 or more in overweight charges plus $150 or more in a separate oversize charge, meaning a single non-compliant bag can realistically cost several hundred dollars beyond the airline's base checked-bag fee.
Why This Matters More Than the Base Checked-Bag Fee
Most baggage-fee comparisons travelers see focus on the base first-checked-bag price, which is a useful number but not the one that creates the largest cost risk. Delta's own domestic base fee, following an April 2026 increase, runs $45 for a first bag and $55 for a second -- a predictable, budgetable cost. The overweight and oversize fees covered above are the genuinely larger, less-predictable risk, since they can multiply a $45 bag into a $250+ one if a traveler misjudges a bag's actual weight or dimensions before arriving at the airport.
An Easy-to-Miss Difference: International Flights Often Include a Free Bag Domestic Ones Don't
This is worth knowing explicitly because it runs opposite to what many travelers assume. On domestic US routes, most major carriers charge for a first checked bag in standard economy -- American Airlines' own domestic first-bag fee is a separate charge. But on long-haul international routes, especially to Europe, Asia, and long-haul Latin America, standard Main Cabin fares on most major US carriers still include at least one free checked bag, a meaningfully more generous allowance than the same airline's domestic policy. The exception worth knowing: Basic Economy fares specifically don't carry this same international allowance -- American's Basic Economy fare to Europe, for instance, still charges a first-bag fee (recently raised to $85 for tickets issued from mid-May 2026), even though a standard Main Cabin fare on the identical route includes the bag for free. The practical takeaway: the fare class booked matters as much as the route itself for whether a first checked bag is genuinely free.
What This Means for Packing a Trip
The practical takeaway is that the 62-inch/50lb baseline is close enough to universal that packing to it is a safe default regardless of airline -- the actual risk and cost variation shows up specifically at the margins, once a bag exceeds that baseline. Weighing a checked bag at home before departure, and knowing the specific operating airline's overweight-fee structure (flat vs. tiered) in advance, is worth the few minutes it takes, particularly on a budget carrier where a single flat fee can apply across a wide, expensive weight range rather than scaling gradually with how far over the limit a bag actually is.
Related Reading
- Packing & Luggage -- this pillar's other cluster pages on the 3-1-1 liquids rule, checked-vs-carry-on rules, and lithium battery restrictions.