I've tried searching this forum and Google as well, but can't find an answer to this simple question. What is the correlation between diameter of tomato fruit size (in inches) vs. weight in ounces? When I shop in seed catalogs for different varieties, they always list potential fruit size in ounces. However, without using a scale (don't own one), I don't know what this means precisely.

In the past, I've graded the size of my tomatoes like this: small = 2-3", medium = 3-4", and large = 4"+.

Can anyone shed some light on this for me? Thanks!

My own definition of a cherry tomato is under two ounces, but some see up to 4 oz as being a cherry tomato, but that would be an exception IMO.

Beyond cherries I have no definition at all and I've grown well over 3,000 varieties.( smile)

Carolyn

Carolyn

If there is such a thing as a "perfectly spherical tomato" its volume in terms of its radius is ; (4/3) * pi *(r)^3, where "r" is half of the diameter. lets take an example. : A tomato is 4 inches in diameter. How much does it weight ?

-- First we calculate its volume in cubic inches, by the above mentioned formula. It comes out = 33.50 cu-in.
-- Now, that tomato is roughly 18.56 fl-oz. (by volume)

-- Assuming that tomato has the same specific gravity as water (or very close to it) then one fl-oz is equal to 1 ounce by weight.

A QUICK SHORT CUT:
weigh in oz = 0.29 (d)(d)(d) OR w(oz) = 0.29 *(d)^3

lets check with the example above ( weight of a tomato in 4 inches in diameter) " w = 0.29 x 4 x4 x4 = 18.56 oz-w

example two: TWO inch in diameter : w= 0.29 x 2 x 2 x 2= 2.32 oz-w

-------------------------------------
conversion: 1 cu-in = 0.554 us fl-oz

bcfromfl - go to any grocery store and take a measuring tape with you. Measure and weigh one of the cherry tomatoes, one of their paste tomatoes and one of their slicing tomatoes. You'll be amazed at the differences in weight. Diameter is irrelevant to a paste or heart shape tomato for example. So a 2" in diameter paste tomato will weight 3x the amount of a 2" cherry tomato.

The real problem is the way you choose to grade tomatoes - forget diameter and inches. Food is measured in weights, in ounces, not by diameters or inches. :) So a trip to the store and using their scale will give you a good mental picture for reference of what a 4-6 oz and an 8-10 oz tomato looks like.

Better yet, pick up an inexpensive kitchen scale.

Dave

Linda

What I did was just that, an approximation.
FIRST we assumed a spherical tomato. In real world there are FEW tomatoes that are near perfect sphere. Just our mother planet Earth is not a pure sphere. Most tomatoes are more like ellipsoid.

The SECOND assumption we made was to take the specific gravity of tomato equal to 1. But as I researched, most red ripe tomatoes IN AVEREAGE have a specific gravity of 0.95.

In my prior approximation: we had : weigh in oz = 0.29 (d)(d)(d) OR w(oz) = 0.29 *(d)^3

Taking into account the ellipsoidality and the specific gravity, we can revise that estimate closer as:

weigh in oz = 0.20 (d)(d)(d) OR w(oz) = 0.29 *(d)^3
That is about 30% reduction. This is the biggest diameter.

Keep in mind that those who post tomato size (in diameter, circumference, weight) they give you just some rough numbers. eg, "has round red fruits 2 to 3" in diameter".

But if you are dead curious you can do this at home. You need a graduated container and a scale.First measure the volume by immersing it in water. Then weigh it. And also measure the diameter with a caliper or by any other way.
.

I am mathematically challenged and have to think up ways to compensate (LOL).

Linda

I must say that I'm surprised my largest Big Beef hybrids, just barely 4" across, would perhaps be considered more than a pound! Maybe the flattened tops and bottoms significantly reduces the volume below a 4" sphere?

Dave's suggestion of using the grocery scales to measure some tomatoes is probably the best bet, although I can't recall how accurate those scales are. I'll have to take a look when I go on Friday.

Thanks again, everyone!

Kathy

Small
1. from 2 1⁄8 inches
2. to 2 9⁄32 inches

Medium
1. from 2¼ inches
2. to 2 17⁄32 inches

Large
1. from 2½ inches
2. to 2 25⁄32 inches

Extra Large
1. from 2¾ inches

1. Will not pass through a round opening with this diameter when the tomato is held with its greatest diameter parallel to the plane of the opening.
2. Will pass through a round opening of this size; the tomato may be held in any position for the test.
The sizes of cherry tomatoes and pear-shaped tomatoes may simply be given in inches or centimeters.

Here is the conversion in metric verion( grams and centimeter)

w(g) = 0.5 *(d^3) ---- (( d= diameter in centimeters))

NOTES:
-- this is for tomatoes that are FAIRLY round not awkwardly lobed, flattened, cat faced, elongated.
BTW:
I bough some tomatoes from store today: did the measurements, checked their specific gravity. Compared the actual weight to the formula. It was right on the money.