Total T4 unit converter

Convert total T4 between µg/dL, nmol/L and ng/mL. Type in either box. The factors come from our catalog and are checked by code.

AI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-03

From

1 µg/dL = 12.8722 nmol/L. Nothing you type here leaves your browser.

The conversion

1 µg/dL = 12.87 nmol/LFrom µg/dL to nmol/L: multiply by 12.87. Back again: divide by 12.87.
1 µg/dL = 10 ng/mLFrom µg/dL to ng/mL: multiply by 10. Back again: divide by 10.

Mass and molar units are linked by the molecular weight: 776.87 g/mol (thyroxine (levothyroxine), C15H11I4NO4). Source: PubChem, National Library of Medicine.

Common values

From zero to about twice the usual upper limit, plus the usual limits themselves.

Total T4 values in µg/dL, nmol/L and ng/mL
µg/dL	nmol/L	ng/mL
2.5	32	25
4.5	58	45
5	64	50
7.5	97	75
10	129	100
12	154	120
12.5	161	125
15	193	150
17.5	225	175
20	257	200
22.5	290	225

Usual ranges in each unit

What labs print as the reference range, by who was tested. Sources for each range are on the Total T4 page.

Usual ranges for Total T4 in µg/dL, nmol/L and ng/mL
Who	µg/dL	nmol/L	ng/mL
2–6	5.3–14.8	68–191	52.6–148
7–11	5.7–14.1	73–181	57–141
12–19	4.7–14.6	61–188	47.4–146
20+	4.5–12	58–154	45–120