European vs US lab reports: units, decimal commas and date formats
European and US lab reports often differ in three ways that matter when you copy numbers: the unit a marker is reported in, the decimal and thousands separators, and the order of day and month in dates. 5,4 can mean 5.4, and 03/04/2026 can mean 3 April or 4 March. Check each before you copy a value or a date.
Not medical advice. This guide describes what the parts of a lab report are and how they are recorded. It does not say what any result means for a person, and it does not recommend treatment, supplements or targets.
What differs, and why it matters
Units. The United States mostly reports conventional mass units such as mg/dL, while the UK, Canada and many European countries use SI units such as mmol/L. Practice differs by country, by lab and by marker, so do not infer the unit from the country. Blood counts differ too: a US report may print K/µL where a European one prints G/L, and T/L for red cells. HbA1c is printed as a percentage in some places and in mmol/mol in others.
Separators. Many European languages write 5,4 where the US writes 5.4, and 1.234,5 where the US writes 1,234.5. A lone comma followed by three digits is ambiguous: 1,234 is one thousand two hundred thirty-four in one convention and one and a bit in the other.
Dates. The US typically writes the month first (03/04/2026), most of Europe the day first (03.04.2026 or 03/04/2026), and some reports the year first (2026-04-03). When both parts are 12 or less, only the rest of the report can settle the order.
Checking a report from another country
Five steps.
Read the unit before the number
Check the unit of every marker against what your sheet already holds for it. Do not assume it from the lab's country.
Identify the decimal convention
Look for a result such as 5,4 or 4,87. If one result uses a decimal comma, expect the whole report to, including the ranges.
Find a date that settles the order
Look anywhere on the report for a date with a day above 12, such as 27.03.2026. It fixes the order of every numeric date on that report.
Write dates and numbers your way
Record dates as YYYY-MM-DD and numbers with a dot, matching the rest of the sheet. Keep the printed text in a note when anything was ambiguous.
Convert only with an exact rule
If the unit differs from your earlier reports, use the units guide and keep the printed value beside the converted one.
Typical differences side by side
Typical, not universal. Read your own report.
| Feature | Typical US report | Typical European report | Check |
|---|---|---|---|
| Glucose and cholesterol | mg/dL | mmol/L in the UK, Ireland, the Nordic countries and Switzerland; often mg/dL in Germany, Italy, Spain and Poland; g/L is common in France | The unit beside each number |
| HbA1c | % | mmol/mol in many countries, sometimes with % beside it | There is no single factor between the two |
| Blood counts | K/µL, 10^3/µL, M/µL | G/L and T/L, or 10^9/L and 10^12/L | Same numbers, different spelling |
| Decimals and thousands | 5.4 and 1,234.5 | 5,4 and 1.234,5, or a space for thousands | Which separator the report uses |
| Dates | MM/DD/YYYY | DD.MM.YYYY, DD/MM/YYYY or YYYY-MM-DD | A day above 12 settles the order |
| Language of headings | English | The local language, such as Ergebnis, Einheit and Referenzbereich | Match columns by role, not by word |
What goes wrong
Most come from assuming the report follows your own conventions.
- Reading 5,4 as 54. A comma dropped as punctuation turns a decimal into a whole number. Compare the digit count with the range printed beside it.
- Misreading a dot as a decimal. 1.234 is one thousand two hundred thirty-four where dots separate thousands, and one and a bit where they mark decimals.
- Swapping day and month silently. 03/04/2026 lands in the wrong month if the order is guessed. If nothing on the report settles it, mark the date as unconfirmed.
- Letting the country set the unit. Two labs in one country can differ, and one lab can use two systems. Read the unit on each report.
- Missing a translated heading. A column named Einheit is the unit and Referenzbereich the range. Match columns by role.
- Pasting into a sheet with the other locale. A spreadsheet set to a comma-decimal locale may read 5.4 as a date or as text. Check how pasted numbers are read.
How BioPanel helps
BioPanel reads both conventions. It detects comma decimals from the results table, reads thousands separators, writes every value with a dot, and recognises labelled collection dates in English, German, French, Spanish, Dutch and Italian. Dotted dates, or any date with a day above 12, make it read day first; when nothing settles the order it reads month first and shows a warning. G/L and T/L are read as 10^9/L and 10^12/L. Headings in those languages are matched on a best-effort basis, so compare the output with the original lab report. Free: 1 file per day, up to 10 pages, no account. Files over 10 pages are converted up to page 10 on the free allowance; a page code converts the whole file, up to 150 pages. See pricing.
Questions people ask
Why do European lab reports use commas for decimals?
In many European languages the comma is the decimal mark and a dot or a space groups thousands. It is the same number written another way: 5,4 is 5.4.
How do I tell whether 03/04/2026 is March or April?
Look for another date on the report with a day above 12, such as 27/03/2026. It fixes the order for the whole document. If none exists, treat the date as unconfirmed.
Do all European labs use mmol/L?
No. Practice differs by country, by lab and by marker. UK and Nordic labs typically use mmol/L for glucose, labs in several other countries print mg/dL, and French labs often print g/L. Read the unit on each report.
What are G/L and T/L?
Giga per litre and tera per litre, used for blood counts. G/L equals 10^9/L and 10^3/µL, and T/L equals 10^12/L and 10^6/µL. The numbers are the same, only the spelling changes.
Is HbA1c in % the same as in mmol/mol?
Both describe one measurement on two scales, but the relation is a formula with an offset, not a single factor. Record each report's unit as printed and do not convert with a multiplier.
Does the country of a lab change what a result means?
This guide covers how reports are written, not what values mean. For that, ask a clinician who knows your history. This is not medical advice.