---
title: "Precision time — PToB"
description: "UTC, local time and Unix timestamps, with a device clock comparison and its estimated uncertainty."
url: "https://ptob.dev/time/"
language: "en"
robots: "noindex, nofollow"
representations: {"application/json":"https://ptob.dev/time/?format=json","text/markdown":"https://ptob.dev/time/?format=markdown"}
format_description: "https://ptob.dev/agent-formats.json"
---

# Precision time

 Acquiring reference

UTC   —:—:—  .—

Waiting for reference

Local time   —:—:—  .—

Waiting for reference

Unix timestamp  seconds

—

ISO 8601  UTC

—

Your device · local    —:—:—  .—

Checking your clock…

Starting the clock check…

Clock offset

—

Uncertainty

—

Round trip

—

Samples

—

## Time coordinates

Local time zone

—

UTC offset

—

Day of year · UTC

—

ISO week · UTC

—

## Your location

Finding your approximate city…

City is estimated from your IP address. VPNs and mobile networks can place you elsewhere. Local time follows your browser’s time zone.

## How this works

Seven HTTPS requests compare your device clock with our server’s recent [Cloudflare NTP reference](https://developers.cloudflare.com/time-services/ntp/). The consistent sample with the lowest estimated uncertainty supplies the result.

Accuracy and privacy

Clock offset is your device time minus the reference: positive means ahead, negative means behind. The uncertainty includes network travel, the NTP reference’s reported uncertainty and an allowance for reference age and browser timers.

The estimate assumes roughly equal travel time in both directions. Unequal routes, browser scheduling and timer rounding can add error. This is an internet clock check, not a precision calibration. Plain NTP is not cryptographically authenticated.

UTC, local time, the analog dial and timestamps represent the same estimated instant. The dial uses a 12-hour UTC face, with tenths of a second on the small dial at 9 o’clock. The 24-hour digital clocks show tenths of a second. Unix timestamps count whole seconds since 1 January 1970 UTC, excluding leap seconds.

This page reads your clock; it does not set it. After the seven-sample check, readouts advance locally without polling. After one minute they are labeled as a local estimate and the comparison expires. Use Check again for a fresh measurement. Returning to the tab or changing the device clock also starts a fresh check.

Approximate city detection uses [ipwho.is](https://ipwhois.io/privacy), which receives your IP address when this page opens. PToB does not store your location or test results.

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```