Topical Dosing Calculator: Fingertip Units to Grams
Topical Dosing Calculator: Fingertip Units to Grams
One fingertip unit is about 0.5 g of ointment from a 5 mm nozzle and covers roughly two adult handprints. This turns the published FTU count for a body region into grams per week, so a reader can see whether a quantity matches a treatment plan.
Fingertip units to grams
Region and schedule to gramsOne whole arm including the hand (4 FTU), twice daily, 14 days, dispensed in 30 g tubes
Formula
Grams per week = FTU × 0.5 × applications per day × 7
1 FTU ≈ 0.5 g ≈ two adult handprints of skin
- what one FTU is
- the MeReC Bulletin’s definition is the quantity expressed from a tube with a 5 mm diameter nozzle along the palmar aspect of an adult index finger from the distal skin crease to the fingertip. FPnotebook gives the coverage as two adult handprints, and disagrees with ITSELF about what that is as a share of body surface — 1.6 per cent in one section of the same page and 2 per cent in another. Both are printed here rather than averaged
- 0.5 g is a convention, not a measurement
- NICE 2007 measured 0.43 g in women and 0.49 g in men. Both are BELOW half a gram, so the convention rounds up: arithmetic at 0.5 g over-states a man’s FTU by about 2 per cent and a woman’s by about 16 per cent. The Frimley guideline states the pair as 0.4 g and 0.5 g instead
- the trunk disagreement
- Primary Care Notebook gives 8 FTU for the front of the trunk and 8 for the back; the NHS Frimley good-practice guideline gives 7 and 7. One FTU is half a gram per application, so over a fortnight twice daily that is 14 g of difference on each side of the trunk. The larger figure is implemented and the smaller is printed in the table below
- it is per APPLICATION
- every published FTU count is the quantity for one application to that region. The weekly and course figures on this page are that count multiplied out, and nothing else
- children are a different table
- the MeReC paediatric figures are banded by age — 3 to 6 months, 1 to 2 years, 2 to 5 years, 6 to 10 years — and are reproduced in the second table below. They are published as BANDS and cannot be interpolated between: there is no published FTU count for an eight-month-old and this page does not invent one
- what it does not tell you
- nothing about potency, nothing about how long a steroid of a given class may be used on a given site, and nothing about whether the quantity is appropriate. Potency classes differ between countries — the UK’s four BNF classes do not map onto the United States’ seven — so no equivalence is offered here at all
Worked example
One whole arm including the hand (4 FTU), twice daily, 14 days, dispensed in 30 g tubes
4 FTU × 0.5 g = 2.0 g per application
2.0 × 2 applications = 4.0 g per day
4.0 × 7 = 28 g per week
4.0 × 14 = 56 g for the course, which is two 30 g tubes with 4 g left over
A single 30 g tube would cover 7.5 days of this plan, which is the arithmetic worth doing before the prescription is written rather than at the review when the eczema has not improved
Switch to once daily and everything halves: 28 g for the course, one tube
Use the Frimley trunk figure of 7 FTU instead of 8 for a front of trunk and the fortnight falls from 112 g to 98 g — a 14 g difference that comes entirely from which published table was read
Adult fingertip units per application, from two sources
| Region | Primary Care Notebook / MeReC | NHS Frimley guideline | Grams per application at 0.5 g |
|---|---|---|---|
| Face and neck | 2.5 | 2.5 | 1.25 |
| Scalp | 3 | 3 | 1.5 |
| One hand, both sides, with fingers | 1 | 1 | 0.5 |
| One whole arm including the hand | 4 | 4 | 2.0 |
| Front of trunk | 8 | 7 | 4.0 or 3.5 |
| Back of trunk | 8 | 7 | 4.0 or 3.5 |
| Buttocks | 4 | 4 | 2.0 |
| One whole leg including the foot | 8 | 8 | 4.0 |
| One foot | 2 | 2 | 1.0 |
| Both soles | 1.5 | 1.5 | 0.75 |
| Genitalia | 0.5 | 0.5 | 0.25 |
| Whole adult body | not stated | about 40 | about 20 |
Paediatric fingertip units per application, by age band
| Age | Face and neck | An arm and hand | A leg and foot | Chest and abdomen | Back including buttocks |
|---|---|---|---|---|---|
| 3 to 6 months | 1 | 1 | 1.5 | 1 | 1.5 |
| 1 to 2 years | 1.5 | 1.5 | 2 | 2 | 3 |
| 2 to 5 years | 1.5 | 2 | 3 | 3 | 3.5 |
| 6 to 10 years | 2 | 2.5 | 4.5 | 3.5 | 5 |
What this adds to the body surface area estimate, and what it does not
Topical treatment fails for two arithmetic reasons far more often than for pharmacological ones: the quantity dispensed cannot physically cover the plan, or it is enough to cover it many times over and is being used for far longer than intended. The fingertip unit exists to make that visible. One FTU is the ribbon of ointment expressed from a tube with a 5 mm nozzle along an adult index fingertip, from the last skin crease to the tip; it weighs about half a gram and covers about two adult handprints of skin.
This page does not estimate body surface area, and that is deliberate. The burn TBSA calculator already owns that estimate — the adult Wallace shares, the paediatric age adjustment, and both published variants of the palm rule, which differ by a factor of two and are printed side by side there rather than reconciled. The body surface area calculator owns body surface area in square metres for drug dosing. What this page adds is the step from a region to a quantity: the published FTU count for that region per application, multiplied out to grams per application, per day, per week and per course, and divided by the tube size actually being dispensed.
Three cautions come with the numbers. The half-gram is a convention rather than a measurement: NICE measured 0.43 g in women and 0.49 g in men, so arithmetic at 0.5 g runs high, by about 2 per cent for a man and about 16 per cent for a woman. The two adult tables read for this page disagree on the trunk — 8 FTU a side against 7 — which is 14 g over a fortnight of twice-daily treatment, and both figures are printed. And the paediatric counts are published as four age bands with nothing between them, so there is no FTU figure for an eight-month-old and none is invented.
What the page deliberately does not do is compare potencies. Topical corticosteroid potency classes are national rather than universal: the United Kingdom uses four classes and the United States seven, and the same molecule at the same strength can sit in different classes in different countries. An equivalence table that silently picked one scheme would be the plausible wrong answer this project exists to avoid, so none is offered. For the severity measures these quantities are usually being applied against, see the PASI, EASI and SCORAD calculators. This page computes the published number and names the guideline or trial that defines its thresholds. It renders no clinical decision.
Frequently asked questions
How many grams is one fingertip unit?
About 0.5 g. NICE’s 2007 atopic eczema guideline measured 0.43 g in women and 0.49 g in men and describes the average as approximately half a gram; an NHS Frimley guideline states 0.4 g and 0.5 g. Both measured figures are below the half-gram convention, so arithmetic at 0.5 g runs slightly high.
How much area does one fingertip unit cover?
About two adult handprints. FPnotebook, which states that figure, gives the equivalent share of body surface as 1.6 per cent in one section of the same page and 2 per cent in another, so the percentage is best treated as approximate. For body surface area itself, use the burn TBSA calculator, which carries both published variants of the palm rule.
How many FTU does a whole arm need?
Four per application for an adult, including the hand — three for the arm alone and one for the hand. At 0.5 g per FTU that is 2 g per application, 4 g a day twice daily, and 56 g over a fortnight, which is two 30 g tubes.
Do the published FTU tables agree with each other?
Almost. The two adult tables read for this page agree on every region except the trunk: Primary Care Notebook gives 8 FTU for the front and 8 for the back, while the NHS Frimley guideline gives 7 and 7. Over a fortnight of twice-daily treatment that is 14 g per side, and both figures are printed here.
Is there an FTU figure for a child of any age?
No. The published paediatric table has four bands — 3 to 6 months, 1 to 2 years, 2 to 5 years and 6 to 10 years — with nothing between or beyond them. There is no published count for an eight-month-old, and interpolating between the bands would be inventing a quantity rather than reading one.
Related calculators
References
- National Prescribing Centre. MeReC Bulletin 1999 — the fingertip unit defined as the quantity expressed from a tube with a 5 mm nozzle onto the distal phalanx of an adult index finger, with the paediatric FTU table by age band.
- Primary Care Notebook. Finger tip units in administration of topical steroids — the adult FTU counts per region, the NICE 2007 mass figures (0.43 g in women, 0.49 g in men) and the paediatric table. primarycarenotebook.com
- Frimley CCG Medicines Optimisation in Care Homes team. Administration of creams and ointments: good practice guideline, version 1, ratified 24 November 2021 — a second adult FTU table, giving trunk front 7 and trunk back 7.
- FPnotebook. Topical medication quantity — one fingertip unit as 0.5 g covering two adult handprints, citing Habif, Clinical Dermatology 4th ed. and Long CC, Clin Exp Dermatol. 1991;16(6):444–7. fpnotebook.com
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/