Introduction
The Thyroid Volume Calculator tells you how big a thyroid gland is. You enter three ultrasound measurements for each lobe (length, width, and depth), and the tool calculates the volume. It gives the volume of the right lobe, the left lobe, and the total gland in milliliters (mL), plus the weight in grams.
Doctors use thyroid volume to check for a goiter (an enlarged thyroid) or a small gland. This calculator treats about 10–15 mL for women and 12–18 mL for men as normal. This calculator compares your total to those ranges and shows if it is small, normal, or enlarged.
The tool uses the ellipsoid formula: Length × Width × Depth × correction factor. You can pick the standard factor (0.5236), the Brunn/WHO factor (0.479) used in research and in children, the Shabana factor (0.529), or type your own. The ellipsoid formula multiplies the three diameters by π/6, which comes to 0.524; a 1981 cadaveric study by Brunn and colleagues found a correction factor of 0.479 more accurate.1 You can enter measurements in cm, mm, or inches, and see results in mL, cm³, L, in³, or fluid ounces.
You also get a step-by-step solution, a bar chart, and a table that shows what your numbers look like under each correction factor. Note that the isthmus (the thin bridge between the lobes) is not counted, which is normal practice in ultrasound. This calculator is a helpful guide, not a diagnosis. Talk to your doctor about your results.
How to use our Thyroid Volume Calculator
Enter your thyroid ultrasound measurements for each lobe, pick a formula, and the calculator gives you the right lobe volume, left lobe volume, total thyroid volume, thyroid mass, and whether the gland is small, normal, or enlarged (goiter).
Correction Factor / Formula: Pick the coefficient used to turn your three measurements into volume. Ellipsoid (π/6 = 0.5236) is the standard choice. Choose Brunn/WHO (0.479) for population or child studies, or Shabana (0.529) for adults checked against CT scans.
Custom coefficient: Only shows if you pick "Custom." Type your own number between 0.1 and 1.0.
Biological Sex: Tap Female or Male. This sets the normal range used to grade your result (10–15 mL for female, 12–18 mL for male).
Right Lobe Length (Craniocaudal): Type the top-to-bottom size of the right lobe and pick cm, mm, or in.
Right Lobe Width (Transverse): Type the side-to-side size of the right lobe and pick your unit.
Right Lobe Depth (Anteroposterior): Type the front-to-back size of the right lobe and pick your unit.
Left Lobe Length (Craniocaudal): Type the top-to-bottom size of the left lobe and pick your unit.
Left Lobe Width (Transverse): Type the side-to-side size of the left lobe and pick your unit.
Left Lobe Depth (Anteroposterior): Type the front-to-back size of the left lobe and pick your unit. You need all three measurements for at least one lobe to get a result.
Volume output unit: Choose how to show the volume: mL, cm³, L, in³, or fl oz.
Mass output unit: Choose how to show the thyroid mass: g, kg, oz, or lb.
Calculate: Click to update your results. You also get a step-by-step solution, a chart, and a table comparing all correction factors.
Reset / Start Over: Clears every field and puts the settings back to default.
Copy Report: Copies your measurements, volumes, mass, and classification as text you can paste into a note or chart.
What Is Thyroid Volume?
The thyroid is a small, butterfly-shaped gland in the front of your neck. It makes hormones that control how fast your body uses energy. Thyroid volume is the total size of that gland, measured in milliliters (mL). Doctors check it to see if the gland is a normal size, too small, or too big.
How Thyroid Volume Is Measured
An ultrasound scan is the standard way to measure the thyroid. The gland has two lobes, one on each side of the windpipe. For each lobe, the sonographer records three numbers:
- Length: top to bottom (craniocaudal)
- Width: side to side (transverse)
- Depth: front to back (anteroposterior)
Each lobe is treated as an egg shape (an ellipsoid). Its volume is found by multiplying the three measurements together and then multiplying by a correction factor. The two lobe volumes are added to get the total. The thin bridge between the lobes, called the isthmus, is usually left out because it adds very little. The same three-measurement method is used for other organs, as in the Prostate Volume Calculator.
The Correction Factor
The correction factor adjusts the box-shaped math down to a rounded, gland-like shape. A few values are used in practice:
- 0.5236 (π/6): the plain ellipsoid formula, most common in daily practice.
- 0.479 (Brunn/WHO): used in large population studies and in children.
- 0.529 (Shabana): tested against CT scan measurements in adults.
The factor you pick changes the answer a little, so reports should say which one was used.
Normal Thyroid Size
In healthy adults, the usual total volume is about 10–15 mL for women and 12–18 mL for men. Because thyroid tissue is about as dense as water, 1 mL of gland weighs about 1 gram. So a 14 mL thyroid weighs roughly 14 grams.
Normal size also depends on body size, age, and how much iodine people get in their food. Children have much smaller glands, and their results are compared to age and height charts instead.
Why Size Matters
A thyroid that is larger than normal is called a goiter. It can come from iodine shortage, Graves' disease, Hashimoto's thyroiditis, or nodules. A large gland may press on the windpipe or food pipe and cause a tight feeling, cough, or trouble swallowing. A gland that is smaller than normal can happen after thyroid surgery, radioiodine treatment, or long-term Hashimoto's damage, and it is often linked to low thyroid hormone.
Volume numbers are also used to track change over time, plan surgery, and work out radioiodine doses. When nodules are found inside the gland, risk is scored with the TIRADS Calculator.
Important Note
Volume alone does not give a diagnosis. Size results are read together with blood tests (TSH, free T4, antibodies), symptoms, and the look of the gland on ultrasound. Talk to a doctor about what your numbers mean for you.