About DataHora

Precise time and date tools, built on open standards

What This Site Does

DataHora.com.br provides accurate time information for all 5,571 Brazilian municipalities and major world cities. We do not rely on the visitor's device clock — which is frequently wrong by seconds or minutes — and instead synchronize with the Cloudflare edge response HTTP Date header, calibrated against upstream NTP stratum-1 servers.

Methodology and Data Sources

IANA Time Zone Database (tzdata)

All timezone math uses the IANA tzdata, the canonical reference maintained by the Internet Assigned Numbers Authority. This covers legislative changes, DST transitions, and historical offsets. Brazil's four active zones (BRT/AMT/ACT and Fernando de Noronha) are handled per-state.

Cloudflare Response Date synchronization

Server-rendered pages derive the reference instant from the HTTP Date response header. This avoids browsers with clocks drifting from NTP and keeps precision within roughly one second across requests.

IBGE Census 2022 data

City-level pages enrich each of the 5,571 Brazilian municipalities with demographic data from the 2022 Demographic Census (IBGE): population, territorial area, density, median age, literacy rate, and traditional populations.

Brazilian labor law (CLT)

Work-hour, overtime and business-day calculators follow the Consolidação das Leis do Trabalho (CLT) and subsequent reforms for overtime, night shift surcharge, and time banking rules.

What We Offer

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Synced Time

Reference instant from Cloudflare HTTP Date, not your browser clock.

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Free Tools

Stopwatch, timer, alarm, epoch converter, pace calculator — no registration.

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Global + Brazil-aware

All 5,571 Brazilian municipalities plus major world cities.

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Open Standards

IANA tzdata + RFC 5322 date header + open IBGE data.

Editorial Team

DataHora Editorial Team. We operate as an anonymous editorial entity — no individual author bylines — and respond to errors, suggestions, or data corrections through the contact channel below.

Last editorial review: April 13, 2026

Contact

Found an error? Spotted a city with the wrong timezone? Please reach out.