Ferritin Unit Converter – Convert ng/mL, µg/L, nmol/L, pmol/L, µg/dL

You just got your blood test back. There’s a number in the ferritin row. And honestly? You have no idea if it’s good, bad, or somewhere in between. Because somehow your lab is using different units from the reference range you found online.

This happens constantly. Labs in different countries — and even different labs in the same country — report ferritin in different units. And unlike simpler measurements, ferritin units can look wildly different. A result of 50 in ng/mL looks nothing like 0.111 in nmol/L. But they mean exactly the same thing.

Let’s clear all of this up. The converter above handles the math instantly. The rest of this guide explains what the numbers actually mean — and why your ferritin level matters far more than most people realize.

Why Ferritin Has So Many Different Units

Ferritin is a large protein. Really large. Its molecular weight is approximately 450,000 daltons — which makes it one of the heaviest proteins routinely measured in clinical labs. That massive size is exactly why the same blood level can be expressed in so many wildly different-looking numbers depending on the unit system used.

Clinical labs in the US, Pakistan, India, and most of the developing world traditionally report in ng/mL (nanograms per milliliter). This is also written as µg/L — and those two are mathematically identical. 1 ng/mL = 1 µg/L. Always. No conversion needed.

Labs using the SI (Système International) system — common in Europe, Australia, and academic research — use molar units like nmol/L or pmol/L. Because ferritin is so heavy, the numbers look tiny in molar units. A completely normal ferritin of 100 ng/mL is only about 0.222 nmol/L. Same amount of ferritin. Completely different-looking number.

Other units like µg/dL, µg/mL, and mg/L show up in research papers, older lab reports, and specialist settings. They’re less common now, but still around.

Ferritin Unit Conversion Table (Quick Reference)

Based on ferritin MW ≈ 450,000 Da. The most commonly used clinical unit is ng/mL (= µg/L).

🔴 Red = potentially low or high · 🟢 Green = commonly targeted optimal range · 🔵 Blue = clinical threshold value

Use the converter at the top for any value not in this table.

What Is Ferritin — and Why Does It Matter So Much?

Ferritin is the protein your body uses to store iron safely. Think of it like a tiny iron vault — it holds iron until your body needs it to make red blood cells, produce energy, grow hair, regulate your immune system, and dozens of other essential jobs.

Here’s the thing most people don’t know. Ferritin levels drop long before hemoglobin does. Your body is smart — it will drain its iron stores first, before letting your red blood cell count fall. So you can have a perfectly normal hemoglobin level and still be significantly iron deficient. Your CBC looks fine. But your ferritin is in the basement. And you feel terrible — exhausted, hair falling out, brain foggy, legs restless at night.

This is called iron deficiency without anemia. And it’s massively underdiagnosed. Especially in women.

The ferritin test is the earliest and most sensitive marker of iron deficiency. It catches the problem weeks or months before it shows up anywhere else on a standard blood panel.

Normal Ferritin Levels by Sex and Age

Here’s the frustrating truth: “normal” varies a lot depending on the lab and the reference population used. These are the most widely cited ranges:

Low Ferritin: Symptoms, Causes, and What That Number Really Means

Low ferritin is one of the most common, most correctable, and most consistently missed diagnoses in modern medicine. It mostly hits women — particularly those who menstruate, are pregnant, or follow plant-based diets. But men get it too, and athletes of both sexes are especially vulnerable.

Symptoms of low ferritin

These tend to appear when ferritin dips below 30–50 ng/mL, even when hemoglobin is still normal:

• Persistent fatigue — the kind that doesn’t get better with sleep. Iron drives mitochondrial energy production. When your iron stores drop, your cells genuinely can’t make ATP efficiently. You’re running on empty at a biological level.
• Hair shedding (telogen effluvium) — hair follicles are metabolically hungry. They’re among the first tissues to get cut off when iron stores fall. Ferritin below 30 ng/mL is strongly linked to diffuse hair loss in women. Most dermatologists now target above 70–80 ng/mL for optimal hair regrowth.
• Brain fog and poor concentration — iron is essential for dopamine synthesis. Low ferritin literally impairs the neurochemistry behind focus, motivation, and mood.
• Restless legs syndrome — that uncomfortable crawling sensation at night that forces you to move your legs? Low ferritin is one of the most common and treatable causes. Most practitioners target above 50–75 ng/mL to resolve it.
• Shortness of breath during exercise — reduced oxygen-carrying capacity even before full anemia sets in.
• Cold hands and feet, pale skin, brittle nails.
• Anxiety and low mood — often misattributed to hormones or stress. Iron repletion can resolve this in 6–8 weeks in many cases.

Common causes of low ferritin

• Heavy menstrual periods — by far the most common cause in premenopausal women
• Pregnancy and postpartum recovery
• Vegetarian or vegan diet (plant-based iron absorbs at about 2–5% vs. 25–35% for heme iron from meat)
• Endurance athletics (runners lose iron through foot-strike hemolysis and sweat)
• Gut malabsorption — celiac disease, Crohn’s, low stomach acid
• Frequent blood donation
• Hidden blood loss (GI bleeding, ulcers)

Ferritin cut-off thresholds that actually matter clinically

High Ferritin: When Your Levels Are Too High

High ferritin gets far less attention than low ferritin. But it’s just as important to understand.

Here’s the catch: elevated ferritin does not automatically mean iron overload. Ferritin is what’s called an acute-phase reactant. That means it rises sharply during inflammation, infection, liver damage, and certain cancers — completely independently of your actual iron stores. Your body releases ferritin into the blood when tissues are stressed. So a high number might mean iron overload. Or it might mean your body is fighting something.

This is why high ferritin must always be interpreted alongside transferrin saturation (TSAT). If ferritin is high and TSAT is above 45%, that’s a strong signal of true iron overload. If ferritin is high but TSAT is normal or low, the cause is almost certainly inflammatory.

Conditions associated with high ferritin

• Hereditary hemochromatosis — the most common genetic disorder in people of Northern European descent. The body absorbs too much iron and has no way to excrete the excess. Ferritin can climb into the thousands if untreated. Treatment is phlebotomy (regular blood removal) to keep ferritin between 50–100 ng/mL.
• Chronic inflammation — rheumatoid arthritis, inflammatory bowel disease, infections
• Liver disease — hepatitis, cirrhosis, fatty liver disease all release stored ferritin into the blood
• Metabolic syndrome and obesity
• Alcohol use disorder
• Certain cancers — especially leukemia, Hodgkin lymphoma, and GI tumors
• Hemophagocytic lymphohistiocytosis (HLH) — a rare but life-threatening condition where ferritin can reach tens of thousands

Ferritin and Thyroid Health — a Connection Most Doctors Miss

This one surprises a lot of people. Iron and thyroid function are deeply linked.

The enzyme responsible for making thyroid hormones — thyroid peroxidase (TPO) — depends on iron. When ferritin falls below 50–60 ng/mL, TPO activity drops. T4-to-T3 conversion becomes impaired. And patients experience classic hypothyroid symptoms — fatigue, brain fog, weight gain, hair loss, cold intolerance — even when their TSH looks completely normal.

If you’ve been told your thyroid is fine but you still feel hypothyroid, and nobody has checked your ferritin — that’s a conversation worth having with your doctor. Functional medicine practitioners commonly target ferritin at 90–110 ng/mL for patients with thyroid conditions.

Understanding Your Lab Report: Units Side by Side

Let’s walk through a real example. You get your result: ferritin 75 ng/mL. Your friend in the UK gets theirs: ferritin 0.167 nmol/L. Your cousin’s Australian report says ferritin 75 µg/L.

All three of you have identical ferritin levels. The unit is the only thing that’s different.

Here’s that same value across all units our converter supports:

The same person. The same blood. Eight different-looking numbers. The converter at the top of this page handles all of them instantly.

Frequently Asked Questions About Ferritin Conversion

Who Usually Needs to Convert Ferritin Units?

More people than you’d think end up on this page — and for good reason:

• Patients comparing lab reports across different countries or different labs that use different unit systems
• Women investigating hair loss — ferritin is one of the first tests ordered when hair is thinning and the cause is unknown
• People with suspected hemochromatosis who need to track ferritin closely in different clinical settings
• Researchers and medical students cross-referencing ferritin data from studies in different countries
• Pregnant women and new mothers monitoring iron status across pregnancy, when reference ranges and units may vary by trimester and by clinic
• Athletes tracking iron status for performance — endurance athletes especially need ferritin well above 50 ng/mL for optimal oxygen transport
• People with chronic fatigue, thyroid issues, or autoimmune conditions who are chasing down causes and comparing notes with online communities or practitioners in other countries

Tips for Getting an Accurate Ferritin Test

The number on your report is only useful if the test was done correctly. A few things that matter:

• Fasting isn’t strictly required for ferritin, unlike glucose or lipids. But some labs prefer you fast for 8–12 hours, and morning testing is standard in many clinics.
• Don’t test during an active infection. Ferritin spikes during illness — even a cold or flu can temporarily push your number up by 50–100%. Wait at least two weeks after recovering.
• Tell your doctor about supplements. Iron supplements taken in the days before the test can slightly raise your result. Some practitioners recommend stopping them 48–72 hours before testing.
• Test CRP at the same time. If CRP is elevated, your ferritin might be falsely high due to inflammation — meaning your true iron stores could be lower than the ferritin number suggests.
• Track it over time. One ferritin result tells you where you are. Three or four results over 12–18 months tell you whether your stores are building, stable, or declining.

Final Word

Ferritin is one of the most important numbers on a blood panel. And one of the most misunderstood.

It’s not just about being anemic or not. It’s about whether your cells have enough iron to make energy, grow hair, regulate your mood, support your thyroid, and carry out hundreds of enzymatic reactions. The difference between ferritin at 15 and ferritin at 80 can be the difference between feeling chronically exhausted and feeling completely fine.

And the units — ng/mL, nmol/L, pmol/L, µg/dL — they’re just different ways of expressing the same measurement. Use the converter at the top of this page whenever you need to translate between them.

Once you know what unit your lab uses, and what range you’re actually aiming for, the number stops being confusing. It just becomes useful information.