The detailed guide below is currently available in English.
What a Unix timestamp measures
A Unix timestamp is simply the number of seconds elapsed since 00:00:00 UTC on January 1, 1970 — the "epoch" — not counting leap seconds. Because it is a single plain number, it is the standard way programs store points in time: sorting, comparing, and arithmetic all become trivial, and no time zone is embedded in the value. The same instant reads as afternoon in New York and midnight the next day in Tokyo, but the timestamp itself never changes.
Seconds versus milliseconds
Most systems count seconds, which produce ten digits for dates in the current era (1700000000 falls in November 2023). JavaScript and some Java libraries instead use thirteen-digit milliseconds, so a value like 1700000000000 is one thousand times larger. This converter auto-detects the longer form: any timestamp of twelve or more digits is treated as milliseconds and converted. If a converted date lands in January 1970, you are probably looking at the wrong unit.
Repères pour la France
Repères locaux pour la France, utiles dans les calculs du quotidien :
- TVA: 20 % en taux normal (5,5 % alimentaire, 10 % restauration) ; les prix sont TTC par loi.
- Monnaie & paiements: Euro (€) ; paiement sans contact et carte bancaire très répandus, virement SEPA instantané en développement.
- Unités & nombres: Système métrique ; virgule décimale et espace pour les milliers : 1 234,56 €.
- Santé: Carte Vitale ; l'Assurance Maladie rembourse en base ≈ 70 % des soins, le reste par mutuelle.
- Pourboire: Service compris : aucun pourboire obligatoire ; arrondir suffit.
Mis à jour : octobre 2026 · valeurs 2025, sources officielles ci-dessus.
Questions fréquentes
Do timestamps handle time zones?
By design, no. A timestamp is always relative to UTC, which is why it is unambiguous. The date shown here is the UTC reading; convert to a local zone only when displaying it to people.
Why does my timestamp show a date in 1970?
You are most likely mixing units — a seconds value interpreted as milliseconds gives dates a thousand times earlier. Values of ten digits are seconds; thirteen digits are milliseconds, which this tool converts automatically.
What happens at 2038?
Older 32-bit systems run out of room on January 19, 2038, when the seconds counter overflows. Modern 64-bit systems, including everything that runs this page, are unaffected and good for hundreds of billions of years.