Health calculators

Thyroid Nodule Calculator

Updated Sep 3, 2026 By Jehan Wadia
Rate Formulas Sources Medical disclaimer
Nodule Dimensions
Values are converted automatically when you change the unit.
Sonographic Features
Composition Select one
Echogenicity Select one
Shape Select one
Margin Select one
Echogenic Foci Select all that apply
TI-RADS Classification
TR4
Moderately Suspicious
Estimated malignancy risk: ~9.1%
Total score: 5 points
Moderate risk — TR4 (~9.1%)
Score Breakdown
CategorySelected OptionPoints
Total—
FNA Recommendation
Follow-Up Surveillance
TI-RADS Reference Scale
TR LevelLabelPointsEst. Malignancy
TR1Benign0 pts~0.3%
TR2Not Suspicious2 pts~1.5%
TR3Mildly Suspicious3 pts~4.8%
TR4Moderately Suspicious4–6 pts~9.1%
TR5Highly Suspicious≥7 pts~35%
Points Contributed by Category
Step-by-Step Solution

Introduction

A thyroid nodule is a lump in the thyroid gland at the front of your neck. Most nodules are harmless, but doctors still check them to be safe. This Thyroid Nodule Calculator helps you do two jobs in one place.

The first tab is TI-RADS Scoring. TI-RADS stands for Thyroid Imaging Reporting and Data System.1 You pick what the ultrasound shows: the nodule's composition, echogenicity, shape, margin, and echogenic foci. Each choice adds points. The calculator adds them up, gives a risk level from TR1 to TR5, and shows the chance the nodule is cancer. If you also type in the three diameters, it tells you if a biopsy (FNA) or a follow-up scan is advised.

The second tab is the Volume Tracker. Type the length, width, and depth from up to four visits. The tool finds the volume of the nodule each time and shows how much it grew or shrank. It flags any jump of 50% or more, since that much growth may mean the nodule needs another look. The same ellipsoid math is used in our Prostate Volume Calculator.

Both tabs work in mm, cm, or inches, and they show the full math step by step. Use this tool to learn and to check numbers, not to replace advice from your doctor.

How to use our Thyroid Nodule Calculator

Enter the nodule's size and what it looks like on ultrasound. The calculator gives you an ACR TI-RADS score, the risk level, a malignancy risk estimate, and FNA biopsy and follow-up advice. The second tab tracks nodule volume over time and flags growth of 50% or more.

TI-RADS Scoring tab

AP Diameter: Type the front-to-back size of the nodule.

Transverse Diameter: Type the side-to-side size of the nodule.

Longitudinal Diameter: Type the head-to-toe (long) size of the nodule. All three are needed for size-based FNA and follow-up advice.

Dimension unit: Pick mm, cm, or inches. Numbers you already typed change over to the new unit for you.

Composition: Pick one: cystic, spongiform, mixed, solid, or cannot tell because of calcification. Spongiform sets the total score to 0 (TR1).

Echogenicity: Pick one: anechoic, hyperechoic or isoechoic, hypoechoic, very hypoechoic, or cannot tell. This compares the nodule's brightness to normal thyroid tissue.

Shape: Pick wider than tall or taller than wide, measured in the transverse plane.

Margin: Pick one: smooth, ill-defined, lobulated or irregular, extra-thyroidal extension, or cannot tell.

Echogenic Foci: Check all that you see: none or comet-tail, macrocalcifications, peripheral (rim) calcifications, or punctate foci. Points add up here.

Calculate and Reset: Press Calculate to see your score, chart, and step-by-step math. Press Reset to clear every choice and size.

Volume Tracker tab

Patient Reference ID: Type a case number only. Do not use names or birth dates. Nothing is saved.

Dimension unit: Pick the unit for the length, width, and depth you measured.

Volume output unit: Pick how you want the volume shown: cm³, mL, mm³, L, or in³.

Year: Type the year of each scan for the baseline visit and up to three follow-ups.

Length, Width, and Depth: Type all three sizes for each visit. The tool finds volume with the ellipsoid formula and shows the percent change from the last visit and from baseline.

Calculate, Reset, and Print: Press Calculate to see volumes, the trend chart, and growth alerts. Press Reset to clear the table. Press Print Results for a paper copy.

What Is a Thyroid Nodule?

The thyroid is a small gland in the front of your neck. It is shaped like a butterfly and makes hormones that control how fast your body uses energy. Those hormones help set your resting energy burn, which you can estimate with a BMR Calculator. A thyroid nodule is a lump or growth inside that gland. Nodules are very common, and most are not cancer. Doctors find many of them by accident during a neck scan for another problem.

How Doctors Check a Nodule

The main test is a thyroid ultrasound. It uses sound waves to make a picture of the lump. No radiation is used. The doctor looks at five things in the picture:

  • Composition – is the nodule solid, filled with fluid, or a mix?
  • Echogenicity – is it darker or brighter than the rest of the thyroid?
  • Shape – is it wider than it is tall, or taller than wide?
  • Margin – is the edge smooth, jagged, or growing into nearby tissue?
  • Echogenic foci – are there bright spots, like calcium, inside it?

ACR TI-RADS Explained

TI-RADS stands for Thyroid Imaging Reporting and Data System. It was made by the American College of Radiology (ACR). Each ultrasound feature earns points. The points are added up to give a risk level from TR1 to TR5:

  • TR1 (0 points) – benign, about 0.3% chance of cancer
  • TR2 (2 points) – not suspicious, about 1.5%
  • TR3 (3 points) – mildly suspicious, about 4.8%
  • TR4 (4–6 points) – moderately suspicious, about 9.1%
  • TR5 (7 or more points) – highly suspicious, about 35%

A spongiform nodule, which looks like a wet sponge, is treated as TR1 no matter what else is seen.

Why Size Matters

The risk level alone does not decide the next step. Size matters too. A needle test called fine-needle aspiration (FNA) takes a few cells from the nodule to check them under a microscope. TI-RADS suggests FNA when the nodule reaches a set size for its risk level: 2.5 cm for TR3, 1.5 cm for TR4, and 1 cm for TR5.2 Smaller nodules with some risk are watched with repeat ultrasounds instead: 1.5 cm for TR3, 1 cm for TR4, and 0.5 cm for TR5.2 TR1 and TR2 nodules usually need no needle test and no follow-up scans.

When someone has many nodules, guidelines say to needle no more than two and to follow no more than four, choosing the ones with the highest scores.

Tracking Nodule Volume Over Time

Nodules are often watched for years to see if they grow. Volume gives a better picture of growth than one measurement alone. It is found with the ellipsoid formula: length × width × depth × π/6. A rise of 50% or more in volume, or a clear jump in size, may mean the nodule needs a needle test or a repeat one. Slow, small changes are common and usually not worrying.

Keep in Mind

TI-RADS scores and volume changes are guides, not answers. Only a doctor can read your ultrasound images and decide what your nodule needs. Blood tests for thyroid hormone, your age, family history, and past radiation to the neck all shape the plan as well.

Formulas used

ACR TI-RADS total score
\text{Total} = P_{\text{composition}} + P_{\text{echogenicity}} + P_{\text{shape}} + P_{\text{margin}} + \sum P_{\text{echogenic foci}}
TI-RADS category from total points 2
\text{TR} = \begin{cases} \text{TR1} & \text{Total} = 0 \text{ or spongiform} \\ \text{TR2} & 1 \le \text{Total} \le 2 \\ \text{TR3} & \text{Total} = 3 \\ \text{TR4} & 4 \le \text{Total} \le 6 \\ \text{TR5} & \text{Total} \ge 7 \end{cases}
Largest nodule dimension used for size thresholds
D_{\max} = \max(D_{AP},\, D_{TR},\, D_{LO})
Nodule volume (ellipsoid formula) 3
V = \frac{\pi}{6} \times L \times W \times D
Percent change from previous visit
\Delta_{\text{prev}} = \frac{V_{n} - V_{n-1}}{V_{n-1}} \times 100\%
Percent change from baseline
\Delta_{\text{base}} = \frac{V_{n} - V_{0}}{V_{0}} \times 100\%
Unit conversion (SI-based)
X_{\text{target}} = \frac{X_{\text{source}} \times k_{\text{source}}}{k_{\text{target}}}

Frequently asked questions

Why does my total score show 0 when I pick spongiform?

Spongiform nodules are almost always benign. ACR TI-RADS says to stop scoring once you mark a nodule spongiform. The calculator sets the total to 0 points and the level to TR1, even if you picked other features. A yellow note appears to explain this.

Why do I see no FNA or follow-up advice?

You need all three diameters typed in. The tool uses the largest of the three to compare against size limits. If one box is blank, the helper text tells you how many of the 3 you have entered.

Why does the follow-up card say FNA takes precedence?

Because the nodule already met the biopsy size limit. Watching with repeat scans is for nodules that pass the follow-up limit but not the FNA limit. Once FNA is advised, that step comes first.

What is the highest score possible?

13 points. That would be solid (2) + very hypoechoic (3) + taller than wide (3) + extra-thyroidal extension (3) + all foci added up. Any score of 7 or more is TR5, so the risk level stops rising past that point.

Why is TR3 exactly 3 points and not a range?

The ACR scale is built that way. 0 points is TR1, 2 points is TR2, 3 points is TR3, 4 to 6 points is TR4, and 7 or more is TR5. There is no 1-point level, since the smallest scoring feature combos skip it.

What formula does the Volume Tracker use?

The ellipsoid formula: length × width × depth × π/6. This is the standard way to estimate the volume of a rounded lump from three ultrasound measurements.

Is cm³ the same as mL?

Yes, they are equal. 1 cm³ = 1 mL. The tool offers both because some reports use one and some use the other. The number itself does not change.

What do the yellow cells with the warning mark mean?

They flag a volume rise of 50% or more. That is the level where guidelines suggest a needle test or a repeat one. The cell turns yellow and a note lists which visits crossed the line.

What is the difference between the two percent change columns?

One compares to the visit right before it. The other compares to the very first (baseline) scan. Slow growth can look small visit to visit but add up to a big change from baseline.

Is the Patient Reference ID saved anywhere?

No. Nothing you type is stored, sent, or kept. It clears when you refresh the page. Use a case number only, never a name or birth date.

Why does my score not match my radiology report?

Two readers can score the same image a bit differently, especially on margin and echogenicity. Also check that you copied the right features. If your numbers differ from the report, trust the report and ask your doctor.

What does taller than wide mean?

The front-to-back size is bigger than the side-to-side size, viewed in the transverse (cross-section) plane. Most benign nodules spread sideways. A tall, narrow shape adds 3 points because it is more worrying.

Why does cannot be determined still add points for echogenicity?

ACR assigns 1 point when brightness cannot be judged. It is a middle value, not a free pass. Margin and composition have their own rules, so their cannot-tell choices score differently.

Sources

  1. Tessler FN, Middleton WD, Grant EG, et al. ACR Thyroid Imaging, Reporting and Data System (TI-RADS): white paper of the ACR TI-RADS Committee. Journal of the American College of Radiology. 2017;14(5):587-595. doi:10.1016/j.jacr.2017.01.046. Accessed September 3, 2026.
  2. Smit J, et al. Cancer risk in thyroid nodules: an analysis of over 1000 consecutive fine needle aspirations. Diagnostics. 2024;14(24):2775. doi:10.3390/diagnostics14242775. Accessed September 3, 2026.
  3. Konca C, et al. Unveiling the accuracy of ultrasonographic assessment of thyroid volume. Journal of Clinical Medicine. 2023;12(20):6619. doi:10.3390/jcm12206619. Accessed September 3, 2026.

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