A 1-gallon resealable food bag measures roughly 10.6 x 10.75 in (26.8 x 27.3 cm). That figure comes from Ziploc’s own product specification, and it is not the only number you will find. Industrial polyethylene bags rated “1 gallon” are converted at 10 x 11 in by distributors such as Uline, Hefty’s 1-gallon slider measures 10-9/16 x 2-3/4 x 9-5/16 in, and a large number of supplier blogs repeat 10 x 12 in. All four figures are in circulation for the same three words.
This guide explains what each number actually measures, gives you a single verified size table for every bag family sold by the gallon, and shows how to turn a “gallon” rating into a real specification you can order against.
Last updated: October 2026
The short answer
1 US gallon = 3.785 litres. A bag labelled “1 gallon” is stating a capacity class. The corner-to-corner dimensions printed on the box are a separate decision made by each manufacturer.
1. Why every source gives you a different number
This is the part almost nobody explains, and it is the reason the search results contradict each other.
1.1 Three different questions are being answered
The four common figures – 10.56 x 10.75 in, 10 x 11 in, 10.5 x 9.2 in, 10 x 12 in – are not competing answers to one question. They are answers to three different ones.
The third figure has no manufacturer behind it. It is a rounded memory that has been copied from page to page until it reads like a standard. If you need a number you can defend to a buyer or a customs officer, use the first two.
1.2 Flat bags are measured in two dimensions, gusseted bags in three
A flat resealable bag has a width and a length. A bag with a folded bottom or side panels has width, depth and height – and the three-dimensional figure is not comparable to the flat one, even at identical capacity.
Hefty’s 1-gallon slider bag is listed as 10-9/16 x 2-3/4 x 9-5/16 in. Ziploc’s 1-gallon press-to-close bag is listed as 10-9/16 x 10-3/4 in. The first number is identical because the flat width of the film is the same. The rest differs because one bag stands up and one lies flat. Comparing them as “gallon bag dimensions” is comparing a box to a sheet.
1.3 Seals and zippers consume usable space
Published dimensions are outside dimensions. The zipper track, the press-to-close channel and the seal area at the edges all sit inside that footprint. A bag sold as 10-9/16 x 10-3/4 in does not offer that area for product. This matters most when you are fitting a fixed-size item – a piece of hardware, a printed booklet, a retail product – rather than a volume of loose material.
1.4 A gallon rating is a nominal class, not a measured volume
No manufacturer fills a bag with water and stops at 3.785 litres. The gallon figure is assigned to a size family, and the manufacturer then decides how much headroom to build in. This is why a bag can hold 5 to 8 lb of ground meat, 15 to 16 cups of soup, or 10 to 12 cups of rice depending on what you put in it – the numbers published by Hefty for its own 1-gallon bag.
2. Gallon to bag size conversion table
For industrial and trade use, capacity is converted to flat bag size using a published table rather than a volume test. The table below is Uline’s official conversion chart, reproduced with its values intact.
Note how the chart is not linear. Doubling from 1 gallon to 2 gallons adds 3 inches of width and 4 of height, because a larger capacity does not simply scale a rectangle – it changes the shape of the load and the amount of bag needed to wrap it. Uline’s own guidance is that the table is a starting point and individual needs may differ.
3. The full size ladder: from snack bag to jumbo
Gallon is one step on a ladder. Buying the wrong step is the most common reason a bag does not fit.
Capacity equivalents for reference: 1 gallon = 4 quarts = 8 pints = 128 fl oz = 16 cups = 3.785 litres.
Related size guides, if your specification is not a resealable bag: tote bag dimensions, standard cosmetic bag sizes, and takeout bag size and material.
4. Quart vs gallon: which one do you actually need
This is the second most common question in the whole family, and the answer is usually decided by one of three things.
Two practical notes that catch people out:
- For carry-on liquids, quart is the rule, not gallon. The TSA’s 3-1-1 rule requires containers of 3.4 oz (100 ml) or less, all carried in one clear quart-sized bag, one bag per passenger. A gallon bag is not a substitute for it, however convenient the extra space looks.
- A quart bag is not a sandwich bag. Standard sandwich bags hold about two thirds of a quart, so if a recipe or a packing list calls for a quart, a sandwich bag will come up short.
For the full breakdown of that size, see our guide to quart size bag dimensions.
5. Thickness (mil): the spec that decides whether the bag survives
Capacity tells you how much fits. Thickness tells you whether the bag holds up. It is the second number on any bag specification, and for anything other than light kitchen use it matters more than the gallon rating.
A mil is one thousandth of an inch. Industrial distributors publish the following guide to what each level is for:
Typical ranges by bag type: flat poly bags 1-8 mil; gusseted bags 1-6 mil; reclosable zipper bags 1.2-8 mil; slider zip bags 2.5-3.5 mil; resealable lip bags 1.5-4 mil.
A note on units, because this trips up importers constantly: thin handled bags such as supermarket T-shirt bags are usually specified in microns, not mil, and the two are not interchangeable. 1 mil equals 25.4 microns, so a T-shirt bag sold at 15 microns is roughly 0.6 mil – around a third of the thickness of a standard 1.75 mil reclosable gallon bag. Comparing the two numbers directly will make a thin bag look heavy.
6. Non-food bags that also use the gallon system
“Gallon” is not exclusive to food storage. The same word appears across several product families with entirely different constructions, which is a second source of confusion.
13-gallon trash bags are a good illustration of why dimensions are unreliable on their own. Published sizes for the same 13-gallon class include 24 x 27 in, 24 x 31 in and 24 x 33 in. The gallon rating is the reliable part; the dimensions depend on the bin shape the manufacturer had in mind.
If your requirement is temperature control rather than containment, capacity is not the governing spec – see how insulated bags keep food cold for the parameters that actually decide it.
7. How to measure your own bag and convert it
If you have a bag in hand and no specification sheet, this takes two minutes.
- Measure the flat width across the bag, seal to seal, at the widest point.
- Measure the length from just below the closure to the bottom seal.
- If the bag has a folded bottom or side gussets, measure the depth too. Lay the bag flat and measure the folded panel.
- Subtract the closure allowance if you are fitting a rigid item. The zipper and seal occupy part of the footprint.
- Estimate capacity by displacement, not by area. Fill the bag with a known quantity – water in a measuring jug, or rice by weight – rather than multiplying width by length.
Step 5 is the one people skip, and it is the reason the width-times-length shortcut keeps producing the wrong number. Two bags with the same flat area can differ by a third in usable volume once gussets, closure and the fill line are taken into account.
8. Buying at volume: turning “1 gallon” into a specification
If you are sourcing bags rather than buying a box at a supermarket, “1 gallon” is not a specification. It is a starting point, and the supplier will still need five things from you before they can quote or produce.
Two practical points for buyers:
- Do not send a gallon rating and expect the supplier to guess. Two factories will read “1 gallon” as 10 x 11 in and 10 x 12 in respectively, and both will consider themselves correct. State the dimensions.
- Do not compare quotes at different thicknesses. A quote at 1.2 mil and a quote at 1.75 mil are not the same product, and the cheaper one will perform differently in the freezer, in transit and under a heavy load.
If you are specifying gallon-size or quart-size bags for a retail, foodservice or industrial programme, our team can work from your dimensions, thickness and closure requirements to a production specification. Browse our bag range or send us your specifications.
9. Frequently asked questions
What is the standard size of a 1-gallon bag? For resealable food bags, Ziploc’s specification is 10-9/16 x 10-3/4 in (26.8 x 27.3 cm). For industrial flat poly bags, distributors convert 1 gallon to 10 x 11 in. There is no single standard across all bag families.
How big is a gallon bag in cm? About 26.8 x 27.3 cm for a Ziploc gallon food bag. A flat industrial 1-gallon poly bag converts to roughly 25.4 x 27.9 cm. If you see 25 x 30 cm quoted, that figure traces back to the 10 x 12 in estimate rather than to a manufacturer’s specification.
How much bigger is a 2-gallon bag? Ziploc’s 2-gallon freezer bag measures 13 x 15 in (33 x 38.1 cm), against 10-9/16 x 10-3/4 in for the 1-gallon bag. That is double the capacity, but only around 30-40% more flat area, because the larger bag is not a simple scaled-up rectangle.
How many gallons is a standard grocery bag? Grocery and T-shirt bags are not sold by gallon rating, so any conversion is approximate. As a reference, shopping bags are generally described as holding around 10-20 litres, which is roughly 2.5 to 5 gallons. If the number matters to you, measure the bag and test by displacement rather than converting.
Can gallon bags hold liquids? Yes, if the closure is fully sealed. Keep the fill line below the closure so the zipper or slider is not sitting in liquid, and use a thicker film for anything with weight or edges.
Can I take gallon bags on a plane? You can pack them, but they do not satisfy the liquids rule. The TSA 3-1-1 rule requires 3.4 oz (100 ml) containers or smaller, all inside one clear quart-sized bag, one per passenger. A gallon bag is larger than the rule allows.
Why do vacuum bags and trash bags also use “gallon”? Because gallon is the everyday American unit for volume, and it is a convenient way to describe a bag family without listing its dimensions. It says nothing about the construction, the film or the closure.
Is a gallon bag the same as a quart bag? No. One gallon equals four quarts. A gallon bag holds about four times the volume of a quart bag and is substantially larger in footprint.
What thickness should a gallon bag be? For everyday food storage, 1.75-2.7 mil is the common range. Freezer use benefits from 2.7-4 mil. Moving, heavy clothing and industrial parts call for 4-6 mil or above. Supermarket-thin handled bags sit far below that, at roughly 13-17 microns (about 0.5-0.7 mil).
Does a “1 gallon” bag hold exactly 1 gallon? No. The rating is a nominal size class. Published capacities for a 1-gallon bag range from 5-8 lb of ground meat to 15-16 cups of soup, depending on what is being loaded and how full it is filled.
The bottom line
A gallon bag does not have one size, because “gallon” was never a dimension in the first place. It is a capacity class that each manufacturer then turns into its own tooling.
The practical rule: trust the dimensions, not the gallon number. When a manufacturer or a distributor publishes both, the dimensions are the specification and the gallon rating is the label. When only the gallon rating is available, ask for the flat width and length before you commit.
That single habit will save you from the four-way contradiction that this topic is famous for.
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