Can and Jar Size Converter (#10, #303, #2½)

Turn the old US commercial can numbers — No. 1, No. 2, No. 2½, No. 300, No. 303, No. 10 and the rest — into millilitres, fluid ounces, cups, net weight and drained weight, both ways, with the distinction between the three that makes substitution go wrong.

Last updated 24 Sep 2026

Can and jar sizes

Can number ⇄ mL, cups, net and drained weight

Which way round?

Which can or jar?The dimension code is the outside size in whole inches and sixteenths: a No. 303 is 3 3/16 in across. The capacity beside it is the published brim-full figure, which is NOT what the code implies — see the first table.

How many of them

The quantity you have, in millilitresWhatever the recipe or the modern tin gives you. 400 g, 411 g, 540 mL and 796 mL are the sizes on the shelf now.

How full is it?21 CFR 155.190 sets the standard of fill for canned tomatoes at not less than 90% of the total capacity of the container.

What is in it, and how much of that is solid?Only the first of these is a figure anybody specifies. The middle two are typical ranges and the page says so rather than pretending.

Density of the packed contents, g/mLTomatoes in juice about 1.03, syrup-packed fruit 1.05 to 1.15, brine about 1.02, a purée up to 1.1. This is what turns a volume into the net weight on the label.

A No. 303 can in section, drawn TO SCALE at its real 3 3/16 by 4 6/16 inch outside dimensions — a geometry, not a circuit. The two short lines at top and bottom are the double seams, which is where the difference between the dimension code and the real capacity goes. The upper line across the can is the 90% fill that 21 CFR 155.190 requires of canned tomatoes; the lower one is the minimum drained weight, half the weight of the water that would fill the can. The gap between those two lines is the liquid you pour down the sink, and it is the reason two cans of the same nominal size are not the same amount of dinner. The lines are at their true heights; the can they are drawn in is the default No. 303 and does not follow the select.

449mLExample

One No. 303 can at the 90% legal fill, tomatoes in juice at 1.03 g/mL

Capacity, then fill, then density, then the drained-weight rule

V_net = n × C × f · m_net = V_net × ρ · m_drained ≥ 0.5 × C × ρ_water

C: the can’s published brim-full capacity in millilitres. A measured figure from the Can Manufacturers Institute sizes, not one computed from the dimension code
f: fill fraction. 21 CFR 155.190 requires not less than 0.90 for canned tomatoes
ρ: density of the packed contents in g/mL, which is what turns a volume into the net weight on the label
0.5: the drained weight of canned tomatoes must be at least half the weight of the water that would fill the can — note that it is measured against the WATER, not against the net weight

Worked example

One No. 303 can at the 90% legal fill, tomatoes in juice at 1.03 g/mL
A No. 303 is 3 3/16 in across and 4 6/16 in tall, and its published brim-full capacity is 16.88 fl oz — 499.2 mL
Multiplying out the dimension code as a cylinder would have given 19.34 fl oz instead, 15% too much, because the code is the outside size
At the 90% fill of 21 CFR 155.190 the contents are 449 mL, which is 1.90 cups — and Nebraska Extension publish “about 2 cups” for a No. 303
At 1.03 g/mL that is 463 g net, 16.3 oz, against the 15 to 17 oz these cans declare
And the minimum drained weight is half the weight of the water that fills the can: 0.5 × 498 = 249 g, 8.8 oz — a little over half of the net weight

The Can Manufacturers Institute dimension codes, and what they do and do not tell you

The three-digit codes are whole inches and sixteenths: a 303 × 406 can is 3 3/16 in across and 4 6/16 in tall. What the fifth and sixth columns show is that you cannot get a volume out of that. Multiply out the cylinder and every published capacity comes in lower — by 24% for the smallest can here and 6% for the largest — because the code is the OUTSIDE size with the double seam and the countersunk ends included, and because the loss is a bigger fraction of a small can. Which is why this page carries the published capacities rather than computing them, and why anyone who tells you a No. 303 holds 19 fl oz has multiplied the code.
Can	Diameter, in	Height, in	Published capacity, fl oz	Capacity from the code as a plain cylinder	The code over-states by	mL	Typical contents
6Z	2.1250	3.5000	6.08	6.88	13.1 %	180	Tomato paste
8Z short	2.6875	3.0000	7.93	9.43	18.9 %	235	Chipotles, small fruit
8Z tall	2.6875	3.2500	8.68	10.22	17.7 %	257	—
No. 1 (Picnic)	2.6875	4.0000	10.94	12.57	14.9 %	324	Mandarin oranges, condensed soup
No. 211 Cylinder	2.6875	4.8750	13.56	15.32	13.0 %	401	Condensed milk
No. 1.25	4.0625	2.3750	13.81	17.06	23.5 %	408	—
No. 2 Vacuum	3.4375	3.3750	14.71	17.36	18.0 %	435	Vacuum-packed corn
No. 300	3.0000	4.4375	15.22	17.38	14.2 %	450	Cranberry sauce, pork and beans
No. 1 Tall	3.0625	4.6875	16.70	19.13	14.6 %	494	—
No. 303	3.1875	4.3750	16.88	19.34	14.6 %	499	Fruit, vegetables, soups
No. 300 Cylinder	3.0000	5.5625	19.40	21.79	12.3 %	574	—
No. 2	3.4375	4.5625	20.55	23.46	14.2 %	608	Juices, soups, vegetables
No. 303 Cylinder	3.1875	5.5625	21.86	24.60	12.5 %	646	—
No. 3 Vacuum	4.2500	3.4375	23.90	27.02	13.1 %	707	—
Jumbo	3.4375	5.6250	25.80	28.93	12.1 %	763	—
No. 2 Cylinder	3.4375	5.7500	26.40	29.57	12.0 %	781	—
No. 2½	4.0625	4.6875	29.79	33.67	13.0 %	881	Peaches, pears, pumpkin
No. 3 Cylinder	4.2500	7.0000	51.70	55.03	6.4 %	1,529	Juice — the old 46 fl oz can
No. 5	5.1250	5.6250	59.10	64.30	8.8 %	1,748	Fruit juice, soups
No. 10	6.1875	7.0000	109.43	116.63	6.6 %	3,236	Catering: fruit, vegetables, tomatoes

USDA’s own table — Food Buying Guide, Table 2

A US Government work and the best single reference for what a catering can actually contains. Two things are worth noticing. First, the No. 10 row is a RANGE — 96 to 117 oz — because the can is a fixed volume and what is in it has a density: a No. 10 of tomatoes and a No. 10 of peach halves in syrup weigh noticeably different amounts. Second, USDA’s table does not carry the No. 303 at all, which is the can old American recipes call for most often; the last row is Nebraska Extension’s figure for it and is labelled as such.
Can size	Net weight or fluid measure as declared	Average volume per can
No. 10	6 lb (96 oz) to 7 lb 5 oz (117 oz)	12 to 13⅔ cups
No. 3 Cylinder	51 oz (3 lb 3 oz) or 46 fl oz	5¾ cups
No. 2½	26 oz (1 lb 10 oz) to 30 oz (1 lb 14 oz)	3½ cups
No. 2 Cylinder	24 fl oz	3 cups
No. 2	20 oz (1 lb 4 oz) or 18 fl oz	2½ cups
No. 300	14 oz to 16 oz (1 lb)	1¾ cups
No. 2 (Vacuum)	12 oz	1½ cups
No. 1 (Picnic)	10½ oz to 12 oz	1¼ cups
8 oz	8 oz	1 cup
No. 303	15 oz to 17 oz	2 cups

Net weight, drained weight and volume are three different numbers

This is the arithmetic that makes substituting one can for another go wrong, and for canned tomatoes it is not a rule of thumb — it is 21 CFR 155.190. The fill of container “is a fill of not less than 90 percent of the total capacity of the container”, and the drained weight “is not less than 50 percent of the weight of water required to fill the container”. Work that through for a No. 10 and the minimum drained weight is 57 oz against a declared net of about 102 oz. You are entitled to a little over half of it as solid food. A No. 10 of tomato PURÉE, by contrast, has nothing to drain and is all of it usable — so two cans of the same nominal size are not the same amount of dinner, and that is the answer to why the recipe went wrong. Only tomatoes have a figure in the regulation; the other drained fractions on this page are typical ranges and are labelled as such.
Can	Brim-full capacity, mL	At the 90% legal fill, mL	Water that would fill it, g	Minimum drained weight, g	In ounces	As a share of net weight
No. 303	499	449	498	249	8.8	54 %
No. 10	3,236	2,913	3,230	1,615	57.0	54 %
No. 2½	881	793	879	440	15.5	54 %

What is on the shelf instead, now

Retail sizes are commercial decisions rather than standards, they differ by country, and they change — the 411 g tin that replaced the No. 303 in the United States is a 400 g tin in Europe and a 398 mL tin in Canada. The third column is therefore a shelf observation and not a cited figure: unlike every other table on this page it has no standard or government document behind it, because there is none to have. So this table is a guide to the right shelf and not a conversion. Where a recipe calls for a whole can of something in a sauce, use the whole modern tin and stop worrying; where it calls for a drained weight of solids, weigh them, because that is the number the old recipe was really about.
The recipe says	Which is	The nearest thing sold today	How close
A No. 303 can	499 mL brim full, about 2 cups of contents	A 411 g / 14.5 oz tin, or a 400 g tin in Europe	Within a few per cent; use the whole tin
A No. 300 can	450 mL, about 1¾ cups	A 400 g / 14 oz tin	Close enough for anything with a sauce
A No. 2 can	608 mL, about 2½ cups	A 540 mL / 19 fl oz Canadian tin	Within 10%
A No. 2½ can	881 mL, about 3½ cups	A 796 mL / 28 oz tin	The 28 oz tin is the direct descendant
A No. 3 cylinder	1,529 mL, 46 fl oz	A 1.36 L / 46 fl oz juice tin, where it survives	Same can
A No. 10 can	3,236 mL, 12 to 13⅔ cups	A No. 10 catering can — it never went away	Same can
A No. 1 picnic can	324 mL, about 1¼ cups	A 300 g condensed soup tin	Within 10%

Preserving jars

Jar sizes are named after US liquid measure, so a pint jar is 16 US fluid ounces, 473 mL. A British pint is 20 imperial fluid ounces, 568 mL — a fifth bigger — so a recipe that fills “four pint jars” means something different on each side of the Atlantic, and an imperial pint of preserve will not go into a US pint jar. The US, UK and metric measures converter has all of them.
Jar	US fl oz	mL	US cups	Note
Quarter-pint / 4 oz jelly jar	4	118	0.500	Jam and jelly
Half-pint (8 fl oz)	8	237	1.000	Jam and jelly
12 oz jar	12	355	1.500	Pickles and sauces
Pint (16 fl oz)	16	473	2.000	The one where the word ‘pint’ is a trap
Pint and a half (24 fl oz)	24	710	3.000	Pickles and sauces
Quart (32 fl oz)	32	946	4.000	Whole fruit, stock
Half gallon (64 fl oz)	64	1,893	8.000	Whole fruit, stock

Three numbers that all get called the size of the can

A can number is not a volume, and this is the first thing to get straight. There are two numbering systems and old recipes use both. The three-digit codes are dimensional: the first figure is whole inches, the next two are sixteenths, so a can marked 303 × 406 is 3 3/16 inches across and 4 6/16 inches tall — and those are OUTSIDE dimensions, measured over the double seam. The single-digit trade numbers — No. 1, No. 2, No. 2½, No. 3, No. 10 — are just names for particular sizes, inherited from the days when they were quoted as the weight of water a can would hold.

You cannot compute a capacity from the code, and the table shows by how much. Treat a No. 303 as a plain cylinder 3 3/16 in by 4 6/16 in and you get 19.34 fluid ounces. The published figure is 16.88. Do it for all twenty sizes and the code over-states the capacity by between 6% and 24%, worst for the smallest cans, because the seam and the countersunk ends take a fixed bite out of every can and that bite is a bigger share of a small one. Anybody who tells you a No. 303 holds 19 fluid ounces has multiplied the code and stopped.

Then there are three different quantities that all get called “the size”, and confusing them is what ruins the recipe. Capacity is the brim-full volume of the empty can, fixed by its geometry. Net weight is what the label declares: the contents including the liquid, which depends on the density of whatever is in there. Drained weight is what is left in the sieve. For canned tomatoes those relationships are not folklore — 21 CFR 155.190 requires the fill to be at least 90% of the can’s capacity and the drained weight to be at least 50% of the weight of water that would fill it. Put a No. 10 through that: 3,236 mL of capacity, so 3,230 g of water, so a minimum drained weight of 1,615 g — 57 oz — against a declared net weight of around 102 oz. You are entitled to a little over half of what you bought as solid food.

Which is exactly why one can does not substitute for another. A No. 10 of whole tomatoes and a No. 10 of tomato purée have the same capacity and similar net weights, and they give you wildly different amounts of usable food, because the purée has nothing to drain and the whole tomatoes are half juice. Same for a can of beans against a can of sweetcorn against a can of peach halves in syrup. If a recipe asks for a can of something in a sauce, use the whole modern tin and do not worry. If it asks for a drained weight, weigh the solids, because that is the number the recipe was actually about.

What the recipe means today. The old sizes map onto modern retail tins closely but not exactly, and modern tins are commercial decisions rather than standards: the No. 303 became a 411 g or 14.5 oz tin in the United States, a 400 g tin in Europe and a 398 mL tin in Canada, all for the same slot on the shelf. A No. 2½ is the ancestor of today’s 796 mL or 28 oz tin. The No. 10 never went anywhere and is still what caterers buy. The fifth table on this page is the mapping, and it is offered as a guide to the right shelf rather than as a conversion factor.

Jars are simpler and have one trap. The preserving ladder — 4 oz, half-pint, 12 oz, pint, pint and a half, quart, half gallon — is named in US liquid measure throughout, so a pint jar is 473 mL. A British pint is 568 mL, a fifth bigger, so a British recipe that makes “two pints of chutney” will not go into two US pint jars. The US, UK and metric measures converter has every one of those measures side by side, and the cups to grams converter turns whatever you drained out of the can into grams.

Frequently asked questions

What is a No. 10 can?

The catering can: 6 3/16 inches across and 7 inches tall, 3,236 mL brim full. USDA’s Food Buying Guide gives its declared contents as 6 lb to 7 lb 5 oz — 96 to 117 oz — and its average volume as 12 to 13⅔ cups. The range is not sloppiness: the can is a fixed volume and what goes in it has a density, so a No. 10 of tomatoes and a No. 10 of peaches in syrup weigh different amounts.

What size is a No. 303 can?

3 3/16 inches in diameter by 4 6/16 inches tall, with a published brim-full capacity of 16.88 US fluid ounces, 499 mL. Nebraska Extension give its contents as 15 to 17 oz and about 2 cups. The nearest thing on a shelf today is a 411 g or 14.5 oz tin in the United States and a 400 g tin in Europe. Note that USDA’s own Food Buying Guide table does not include the No. 303, even though it is the can American recipes of the 1950s ask for most often.

How do can size numbers work?

Two systems, muddled together. The three-digit codes are dimensional: whole inches then sixteenths of an inch, so a can marked 303 × 406 is 3 3/16 in across and 4 6/16 in tall, measured OUTSIDE the double seam. The single-digit trade numbers — No. 1, No. 2, No. 2½, No. 3, No. 10 — are legacy names for particular sizes and do not encode anything. And the code will not give you a capacity: multiply out the cylinder and you over-estimate by 6% to 24%, because of the seam, the countersunk ends and the headspace.

Why is the drained weight so much less than the net weight?

Because the liquid counts towards the net weight and you throw it away. For canned tomatoes the numbers are actually specified: 21 CFR 155.190 requires a fill of at least 90% of the container’s capacity and a drained weight of at least 50% of the weight of water that would fill it. For a No. 10 that works out at a minimum of 57 oz of solids against a declared net of around 102 oz — a little over half. A can of purée or paste, by contrast, is all usable. This is why swapping a can of beans for a can of tomatoes of the same nominal size does not give you the same amount of food.

How many cups in a can?

It depends on the can and on whether you mean everything in it or just the solids. USDA’s Food Buying Guide gives the total: 1¼ cups for a No. 1 picnic, 1¾ for a No. 300, 2½ for a No. 2, 3½ for a No. 2½, 5¾ for a No. 3 cylinder and 12 to 13⅔ for a No. 10. Nebraska Extension give 2 cups for a No. 303. Drained, you get roughly half to two thirds of those figures for anything packed in liquid, and all of them for a solid pack.

Is the 90% fill rule true of every canned food?

No, and this page is careful about it. The 90% fill and the 50% drained weight are 21 CFR 155.190, which is the standard for canned tomatoes. Other canned vegetables and fruits have their own standards of identity and grade standards, and the drained weights vary by commodity or are not specified at all. The tomato figures are used here because they are the ones that are actually written down; the other drained fractions offered are typical ranges and are labelled as such.

What about jar sizes — is a pint jar a pint?

A US pint, yes: 16 US fluid ounces, 473 mL. Not a British pint, which is 20 imperial fluid ounces and 568 mL, a fifth larger. The standard preserving ladder is 4 oz, half-pint, 12 oz, pint, pint and a half, quart and half gallon, all named in US measure, and a British recipe written in pints will overfill every one of them.

Related calculators

References

U.S. Department of Agriculture, Food and Nutrition Service. Food Buying Guide for Child Nutrition Programs, Table 2: Common Can and Jar Sizes, Average Net Weight or Fluid Measure and Average Volume Per Can. foodbuyingguide.fns.usda.gov. A work of the United States Government and in the public domain. The source of the declared net weights and average cup volumes on this page, including the No. 10 at 6 lb to 7 lb 5 oz and 12 to 13⅔ cups.
Can Manufacturers Institute can-size nomenclature (cancentral.com), as tabulated for the twenty standard sizes: the three-digit code gives the nominal outside dimensions in whole inches and sixteenths, so a 307 × 512 is 3 7/16 in by 5 12/16 in. The published brim-full capacities in the first table are from that tabulation; the geometric comparison beside them is this page’s own arithmetic.
Nebraska Extension, How to Interpret Can Size Numbers (food.unl.edu): No. 300 at 1¾ cups and 14 to 16 oz; No. 303 at 2 cups and 15 to 17 oz; No. 2 at 2½ cups and 20 oz; No. 2½ at 3½ cups and 27 to 29 oz; No. 10 at 3 quarts and 6½ to 7 lb 5 oz. Used for the No. 303, which USDA’s own table omits.
Code of Federal Regulations, 21 CFR 155.190, Canned tomatoes. § 155.190(c)(1): “the standard of fill of container for canned tomatoes is a fill of not less than 90 percent of the total capacity of the container”. § 155.190(b)(1)(i): the drained weight “is not less than 50 percent of the weight of water required to fill the container”. These are the only drained-weight figures on this page that are specified rather than typical.
Code of Federal Regulations, 21 CFR Part 155, Canned Vegetables, consulted for whether a general standard of fill or drained weight applies to canned vegetables other than tomatoes. It does not: § 155.200 sets identity and ingredients, and § 155.120 sets quality factors for canned green and wax beans (defect and size limits expressed per 340 g of drained weight) without specifying a drained weight. Hence the refusal on this page to publish a drained fraction per food.
National Institute of Standards and Technology. NIST Handbook 44, Appendix C, General Tables of Units of Measurement. The US liquid gallon is 231 cubic inches exactly and the international inch is 25.4 mm exactly; every volume on this page descends from those two definitions.
U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy. fdc.nal.usda.gov. A work of the United States Government and in the public domain. Every gram weight, water content and sugar profile on this page is a published FoodData Central value and the FDC id is given in the table beside it.