Unix Calculator

    Python Unix Timestamps Cheatsheet

    Last updated May 2026

    Python Timestamps Cheatsheet

    Every timestamp operation you need. Print or save as PDF.

    Get Current Timestamp

    import time
from datetime import datetime, timezone

# Unix seconds (float)
time.time()
# → 1733529600.123

# Unix seconds (integer)
int(time.time())
# → 1733529600

# datetime object (UTC)
datetime.now(timezone.utc)

# datetime object (local)
datetime.now()

    Timestamp → datetime

    from datetime import datetime, timezone

ts = 1733529600

# → UTC datetime
datetime.fromtimestamp(ts, tz=timezone.utc)

# → Local datetime  
datetime.fromtimestamp(ts)

# → ISO 8601 string
datetime.fromtimestamp(ts, tz=timezone.utc).isoformat()
# "2024-12-07T04:00:00+00:00"

# → Formatted string
datetime.fromtimestamp(ts, tz=timezone.utc) \
    .strftime('%Y-%m-%d %H:%M:%S UTC')

    datetime → Timestamp

    from datetime import datetime, timezone

# datetime → Unix seconds (MUST be UTC-aware)
dt = datetime(2024, 12, 7, 4, 0, 0, tzinfo=timezone.utc)
int(dt.timestamp())
# → 1733529600

# String → Unix seconds
dt = datetime.fromisoformat('2024-12-07T04:00:00+00:00')
int(dt.timestamp())

# Naive datetime (assume UTC) → timestamp
dt_naive = datetime(2024, 12, 7, 4, 0, 0)
int(dt_naive.replace(tzinfo=timezone.utc).timestamp())

    Timezone Handling

    from datetime import datetime, timezone
import zoneinfo  # Python 3.9+

ts = 1733529600
utc_dt = datetime.fromtimestamp(ts, tz=timezone.utc)

# Convert to any timezone
ny_tz = zoneinfo.ZoneInfo('America/New_York')
ny_dt = utc_dt.astimezone(ny_tz)

# Python 3.8 and below — use pytz
# import pytz
# ny_tz = pytz.timezone('America/New_York')
# ny_dt = utc_dt.astimezone(ny_tz)

# Format with timezone name
ny_dt.strftime('%Y-%m-%d %H:%M:%S %Z')
# "2024-12-06 23:00:00 EST"

    strftime Format Codes

    # Common format codes
%Y  # 4-digit year:        2024
%m  # Month (01-12):       12
%d  # Day (01-31):         07
%H  # Hour 24h (00-23):    04
%I  # Hour 12h (01-12):    04
%M  # Minutes (00-59):     00
%S  # Seconds (00-59):     00
%f  # Microseconds:        000000
%Z  # Timezone name:       UTC
%z  # UTC offset:          +0000
%A  # Weekday name:        Saturday
%j  # Day of year:         342
%U  # Week number:         49

# Common patterns
'%Y-%m-%d'           # 2024-12-07
'%Y-%m-%dT%H:%M:%SZ' # ISO 8601 UTC
'%d/%m/%Y %H:%M'     # 07/12/2024 04:00

    ⚠️ Common Mistakes

    import time
from datetime import datetime, timezone

# ✗ WRONG — naive datetime, timezone ambiguous
dt = datetime(2024, 12, 7, 4, 0, 0)
dt.timestamp()  # Assumes LOCAL time, not UTC!

# ✓ RIGHT — always add UTC timezone
dt = datetime(2024, 12, 7, 4, 0, 0, tzinfo=timezone.utc)
int(dt.timestamp())  # → 1733529600

# ✗ WRONG — time.time() is a float
ts = time.time()  # 1733529600.1234

# ✓ RIGHT — convert to int
ts = int(time.time())

# ✗ WRONG — utcnow() is deprecated in 3.12
# datetime.utcnow()

# ✓ RIGHT
datetime.now(timezone.utc)

    Date Arithmetic

    from datetime import datetime, timezone, timedelta

now = datetime.now(timezone.utc)

# Add/subtract time
tomorrow  = now + timedelta(days=1)
last_week = now - timedelta(weeks=1)
in_1_hour = now + timedelta(hours=1)

# Duration between two datetimes
delta = dt2 - dt1
delta.total_seconds()  # float
delta.days             # integer days

# Duration between two Unix timestamps
diff = ts2 - ts1  # seconds
days  = diff // 86400
hours = (diff % 86400) // 3600

    Expiry Checks

    import time

now = int(time.time())

# Check JWT expiry
is_expired = payload['exp'] < now

# Time until expiry
seconds_left = payload['exp'] - now
minutes_left = seconds_left // 60

# Create expiry timestamps
ONE_HOUR = 3600
expiry   = now + ONE_HOUR

SESSION_TTL    = 30 * 60  # 30 minutes
session_expiry = now + SESSION_TTL
is_valid       = now < session_expiry

    Parsing Common Formats

    from datetime import datetime

# ISO 8601
datetime.fromisoformat('2024-12-07T04:00:00+00:00')

# Custom format
datetime.strptime(
    '07/Dec/2024:04:00:00 +0000',
    '%d/%b/%Y:%H:%M:%S %z'
)

# Unix timestamp string → int
ts = int('1733529600')

# Apache/nginx log timestamp → epoch seconds
datetime.strptime(
    '07/Dec/2024:04:00:00 +0000',
    '%d/%b/%Y:%H:%M:%S %z'
).timestamp()

    Useful Constants

    import time
from datetime import datetime, timezone

ONE_MINUTE = 60
ONE_HOUR   = 3_600
ONE_DAY    = 86_400
ONE_WEEK   = 604_800
ONE_MONTH  = 2_592_000   # 30 days
ONE_YEAR   = 31_536_000  # 365 days

# Famous timestamps
UNIX_EPOCH  = 0           # 1970-01-01
Y2K         = 946684800   # 2000-01-01  
Y2038_LIMIT = 2147483647  # 2038-01-19

# Current timestamp
NOW = int(time.time())

# Is current year a leap year?
year = datetime.now(timezone.utc).year
is_leap = (year % 4 == 0 and year % 100 != 0) or year % 400 == 0

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