timefyi

Pure Python timezone engine for developers. Look up current times in any IANA timezone, compute time differences, find business hours overlap across international teams, convert datetimes, and calculate sunrise/sunset -- all built on stdlib zoneinfo with zero core dependencies.

Check current times worldwide at timefyi.com -- world clock, timezone comparisons, and business hours planning.

Table of Contents

• Install
• Quick Start
• Understanding Timezones
• Business Hours Across Timezones
• Sunrise & Sunset
• Command-Line Interface
• MCP Server (Claude, Cursor, Windsurf)
• REST API Client
• API Reference
  • Current Time & Conversion
  • Business Hours & Comparison
  • Sunrise & Sunset
  • Formatting
• Features
• Learn More About Time Zones
• Utility FYI Family
• License

Install

pip install timefyi              # Core engine (zero deps, uses stdlib zoneinfo)
pip install "timefyi[sun]"       # + Sunrise/sunset (astral)
pip install "timefyi[cli]"       # + Command-line interface
pip install "timefyi[mcp]"       # + MCP server for AI assistants
pip install "timefyi[api]"       # + HTTP client for timefyi.com API
pip install "timefyi[all]"       # Everything

Quick Start

from timefyi import get_current_time, get_time_difference, convert_time

# Current time in Seoul
info = get_current_time("Asia/Seoul")
info.utc_offset           # '+09:00'
info.current_time          # datetime with KST
info.is_dst                # False

# Time difference
diff = get_time_difference("America/New_York", "Asia/Seoul")
diff.difference_hours      # 14.0 (or 13.0 during DST)
diff.difference_str        # '+14h'

# Convert time across timezones
from datetime import datetime
converted = convert_time(datetime(2026, 3, 4, 14, 30), "America/New_York", "Asia/Seoul")

Understanding Timezones

Timezones are governed by the IANA Time Zone Database (also called tzdata or the Olson database), maintained by a volunteer community and released several times per year. Each timezone is identified by a region/city string like "Asia/Seoul" or "America/New_York" rather than abbreviations like "KST" or "EST" -- because abbreviations are ambiguous ("CST" could mean Central Standard Time, China Standard Time, or Cuba Standard Time).

Abbreviation	Ambiguous?	Possible Meanings	Use IANA Instead
CST	Yes	Central Standard (US), China Standard, Cuba Standard	America/Chicago, Asia/Shanghai, America/Havana
IST	Yes	India Standard, Ireland Standard, Israel Standard	Asia/Kolkata, Europe/Dublin, Asia/Jerusalem
EST	Yes	Eastern Standard (US), Eastern Standard (Australia)	America/New_York, Australia/Sydney
BST	Yes	British Summer Time, Bangladesh Standard Time	Europe/London, Asia/Dhaka
PST	No	Pacific Standard Time	America/Los_Angeles
KST	No	Korea Standard Time	Asia/Seoul

from timefyi import get_current_time

# Always use IANA identifiers -- abbreviations are ambiguous
seoul = get_current_time("Asia/Seoul")          # UTC+9, no DST observed
new_york = get_current_time("America/New_York") # UTC-5 (EST) or UTC-4 (EDT)
london = get_current_time("Europe/London")      # UTC+0 (GMT) or UTC+1 (BST)

# DST transitions change the UTC offset automatically
# New York is UTC-5 in winter, UTC-4 in summer
# The IANA identifier handles this transition seamlessly

A UTC offset is the number of hours (and sometimes minutes) added to or subtracted from Coordinated Universal Time. Offsets range from UTC-12:00 to UTC+14:00, with several zones at 30- or 45-minute intervals (e.g., India at UTC+5:30, Nepal at UTC+5:45, Chatham Islands at UTC+12:45).

Offset	Timezone Example	Major City
UTC-12:00	AoE (Baker Island)	--
UTC-8:00	America/Los_Angeles	Los Angeles
UTC-5:00	America/New_York	New York
UTC+0:00	Europe/London	London
UTC+1:00	Europe/Paris	Paris, Berlin
UTC+5:30	Asia/Kolkata	Mumbai, Delhi
UTC+5:45	Asia/Kathmandu	Kathmandu
UTC+8:00	Asia/Shanghai	Beijing, Singapore
UTC+9:00	Asia/Seoul	Seoul, Tokyo
UTC+12:45	Pacific/Chatham	Chatham Islands
UTC+14:00	Pacific/Kiritimati	Line Islands

Daylight Saving Time (DST) shifts the local clock forward by one hour during summer months. Not all countries observe DST -- most of Africa, Asia, and South America do not. When DST transitions occur, they happen at different dates in different countries, making timezone arithmetic non-trivial.

Learn more: Browse Time Zones · World Clock · ## Business Hours Across Timezones

Finding overlapping work hours is one of the most common timezone challenges for distributed teams. A team spanning New York, London, and Seoul has only a narrow window where all three are in standard business hours (9:00-17:00 local).

Team Pair	UTC Overlap Window	Local Overlap	Overlap Hours
NYC + London	14:00-17:00 UTC	NYC 9-12, London 14-17	3 hours
NYC + Seoul	23:00-01:00 UTC	NYC 18-20, Seoul 8-10	~2 hours
London + Seoul	00:00-08:00 UTC	London 0-8, Seoul 9-17	0 hours (no standard overlap)
NYC + London + Seoul	--	--	0 hours (requires flex scheduling)

from timefyi import get_business_hours_overlap, get_hourly_comparison

# Find UTC hours where all timezones are in business hours (9-17 local)
overlap = get_business_hours_overlap(["America/New_York", "Europe/London", "Asia/Seoul"])
# Returns list of overlapping UTC hours -- useful for meeting scheduling

# Side-by-side hourly comparison for two offices
comparison = get_hourly_comparison("America/New_York", "Asia/Seoul")
# Shows what each hour in New York corresponds to in Seoul

Learn more: Time Zone Converter · Countries

Sunrise & Sunset

Sunrise and sunset times depend on geographic latitude, longitude, and the date. At the equator, day length varies by only ~30 minutes throughout the year. At 60 degrees latitude (e.g., Helsinki, Anchorage), day length swings from ~6 hours in winter to ~18 hours in summer. The [sun] extra uses the astral library for astronomical calculations including dawn (civil twilight), sunrise, sunset, and dusk.

# Requires: pip install "timefyi[sun]"
from timefyi import get_sun_info

# Sunrise and sunset for Seoul, South Korea
sun = get_sun_info(37.5665, 126.978, "Asia/Seoul")
sun.sunrise    # datetime -- when the sun crosses the horizon
sun.sunset     # datetime -- evening sunset time
sun.dawn       # datetime -- civil twilight begins (sun 6 degrees below horizon)
sun.dusk       # datetime -- civil twilight ends

Learn more: World Clock · Glossary

Command-Line Interface

pip install "timefyi[cli]"

timefyi now America/New_York
timefyi diff America/New_York Asia/Seoul
timefyi convert "2026-03-04 14:30" America/New_York Asia/Seoul
timefyi overlap America/New_York Asia/Seoul Europe/London
timefyi sun --lat 37.5665 --lon 126.978 --tz Asia/Seoul

MCP Server (Claude, Cursor, Windsurf)

Add timezone tools to any AI assistant that supports Model Context Protocol.

pip install "timefyi[mcp]"

Add to your claude_desktop_config.json:

{
    "mcpServers": {
        "timefyi": {
            "command": "python",
            "args": ["-m", "timefyi.mcp_server"]
        }
    }
}

Available tools: current_time, time_difference, convert_time, business_hours_overlap, sun_info

REST API Client

pip install "timefyi[api]"

from timefyi.api import TimeFYI

with TimeFYI() as client:
    result = client.time("seoul")
    diff = client.difference("new-york", "seoul")

Full API documentation at timefyi.com.

API Reference

Current Time & Conversion

Function	Description
get_current_time(timezone) -> CityTimeInfo	Current time with UTC offset, abbreviation, DST status
convert_time(dt, from_tz, to_tz) -> datetime	Convert datetime between timezones
get_time_difference(tz1, tz2) -> TimeDifferenceInfo	Hours difference between two timezones

Business Hours & Comparison

Function	Description
get_business_hours_overlap(timezones) -> list	UTC hours where all timezones are in business hours
get_hourly_comparison(tz1, tz2) -> list	Side-by-side hour mapping between two timezones

Sunrise & Sunset

Function	Description
get_sun_info(lat, lon, timezone) -> SunInfo	Dawn, sunrise, sunset, dusk, day length (requires [sun])

Formatting

Function	Description
format_offset(hours) -> str	Format UTC offset (e.g., "+09:00")
format_difference(hours) -> str	Format time difference (e.g., "+14h")

Features

• Current time -- timezone lookup with UTC offset, abbreviation, DST status
• Time difference -- hours between any two IANA timezones
• Time conversion -- convert datetime across timezones
• Business hours overlap -- find UTC hours where multiple timezones overlap
• Hourly comparison -- side-by-side hour mapping between timezones
• Sunrise/sunset -- dawn, sunrise, sunset, dusk, day length (optional astral)
• Formatting -- UTC offset and difference strings
• CLI -- Rich terminal output with timezone tables
• MCP server -- 5 tools for AI assistants (Claude, Cursor, Windsurf)
• REST API client -- httpx-based client for timefyi.com API
• Zero dependencies -- core engine uses only stdlib zoneinfo and datetime
• Type-safe -- full type annotations, py.typed marker (PEP 561)

Learn More About Time Zones

• Tools: World Clock · Time Zone Converter · - Browse: Time Zones · Countries
• Guides: Glossary · - API: REST API Docs · OpenAPI Spec

Utility FYI Family

Part of the FYIPedia open-source developer tools ecosystem — everyday developer reference and conversion tools.

Package	PyPI	npm	Description
unitfyi	PyPI	npm	Unit conversion, 220 units -- unitfyi.com
timefyi	PyPI	npm	Timezone ops & business hours -- timefyi.com
holidayfyi	PyPI	npm	Holiday dates & Easter calculation -- holidayfyi.com
namefyi	PyPI	npm	Korean romanization & Five Elements -- namefyi.com
distancefyi	PyPI	npm	Haversine distance & travel times -- distancefyi.com

Embed Widget

Embed TimeFYI widgets on any website with timefyi-embed:

<script src="https://cdn.jsdelivr.net/npm/timefyi-embed@1/dist/embed.min.js"></script>
<div data-timefyi="entity" data-slug="example"></div>

Zero dependencies · Shadow DOM · 4 themes (light/dark/sepia/auto) · Widget docs

License

MIT