Baggage Weight Calculator

How airline baggage weight limits work

US airlines set two separate limits on a checked bag: a weight limit and a size limit. This calculator deals with weight, which is the one that generates fees at the counter. The standard domestic allowance is 50 lb (22.7 kg) per bag, and the three budget carriers. Spirit, Frontier and Allegiant, use 40 lb (18.1 kg) instead.

Above the limit, airlines do not refuse the bag. They charge a tiered overweight fee on top of the normal checked-bag fee, and the tier depends on how heavy the bag is. The usual structure is a first tier up to about 70 lb and a second tier from 71 to 100 lb, with the fee roughly doubling between them. Above 100 lb the bag is refused outright, that cap is universal.

The practical consequence is that the fee for being 5 lb over is often the same as the fee for being 19 lb over, because the tiers are wide. If you are going to be over, be over in the cheap tier and no more. And because the overweight fee is charged per bag, two slightly heavy bags cost twice as much as one.

Airline checked-bag weight limits at a glance

These are the typical published US domestic figures. Fees are per bag, in US dollars, and change often, check your airline before you fly.

Two patterns are worth noticing. First, the budget carriers charge more for the first checked bag but less for an overweight one, so a heavy bag is relatively cheaper on Spirit than on Delta, while a normal bag is much more expensive. Second, Southwest and JetBlue sit in the middle on both counts, and Southwest is the only airline here that still includes checked bags in the fare.

Worked example: a 57 lb suitcase on Delta

You pack for a two-week trip and the bathroom scale says the suitcase is 57 lb. Delta's limit is 50 lb, so you are 7 lb over, and 7 lb over lands in the 51 to 70 lb tier, which costs $100 on top of the first-bag fee of about $35. That is $135 for one bag each way, or $270 round trip.

Now do the arithmetic the other way. Seven pounds is a pair of sneakers (2 lb), a pair of jeans (1.5 lb), a hoodie (1.5 lb) and a toiletry bag (2 lb). Wearing the sneakers and the hoodie and putting the rest in a carry-on takes the bag to 50 lb and the fee to $0. The saving is $100 per leg for about four minutes of repacking.

If you cannot repack, say the weight is gifts or equipment, compare the two options before you fly. A second checked bag at about $45 is almost always cheaper than a $100 overweight fee, and it gives you room to bring things home.

Worked example: a 24 kg bag on Spirit

International tickets usually quote kilos, so it pays to convert before you compare airlines. A bag weighing 24 kg is 24 x 2.2046 = 52.9 lb.

On a legacy carrier with a 50 lb limit, 52.9 lb is in the 51 to 70 lb tier, about $100. On Spirit, Frontier or Allegiant, the limit is only 40 lb (18.1 kg), so the same bag is 12.9 lb over and falls into the second tier, which is about $100 on Spirit and Frontier and $75 on Allegiant.

The lesson is that the metric and imperial limits are not the same size. Fifty pounds is 22.7 kg, and a 23 kg allowance is 50.7 lb, so a bag weighed at 23.0 kg on an international scale is fractionally over a US 50 lb limit. Airlines almost always weigh in kilos at international check-in, so a 22.5 kg bag is the safe target for a 50 lb allowance.

How to shave 10 lb without buying anything

Most overweight bags are 5 to 12 lb over, which is exactly the weight of the things people pack "just in case". The reliable moves, roughly in order of pounds saved per minute of effort:

• Wear your heaviest layer. Boots, a coat and a hoodie can be 5 to 6 lb off the scale and onto your body, which is not weighed.
• Move toiletries to a carry-on. Full-size shampoo, conditioner and sunscreen add 3 to 5 lb, and liquids over 3.4 oz have to be checked anyway only if you are not checking a bag, so decant into travel sizes and keep them with you.
• Carry the chargers and electronics. A laptop, charger brick and cable set is 4 to 6 lb and belongs in your personal item.
• Pack fewer shoes. Shoes are the densest thing most people pack: two pairs is 3 lb, four pairs is 6 lb.
• Ship the heavy gifts. A flat-rate box ahead of you is often cheaper than a single overweight fee.

If you want a target, aim for 45 lb rather than 50 lb on a 50 lb allowance. That leaves room for the souvenirs you buy on the way home, which is where most return-trip overweight fees come from.

Weighing your bag before you get to the airport

You do not need a luggage scale. A bathroom scale works if you weigh yourself holding the bag and subtract your own weight, stand on the scale alone first, then again with the bag, and subtract. It is accurate to about a pound, which is close enough for a 50 lb limit.

At the airport, the scale at check-in is the official one, and airlines do not negotiate. If your bag is over, you have three options at the counter: pay the overweight fee, move items to a carry-on in front of the agent, or buy a second bag if you have one. Asking to move things is completely normal and takes a minute.

Two official sources are worth knowing before you travel. The TSA's What Can I Bring page settles what is allowed in a carry-on versus a checked bag, and the Department of Transportation's Aviation Consumer Protection office publishes the rules airlines have to follow on baggage fees, including refunds when bags are delayed. The FAA sets the safety rules that govern how heavy a bag may be loaded.