How to Work with Dates and Times in Ruby

Ruby gives you several ways to work with dates and times. This cookbook covers the most common patterns.

Getting Current Date and Time

Time.now        # => 2026-03-12 20:30:00 +0000
Date.today      # => #<Date: 2026-03-12>

Parsing Date Strings

Time.parse("2026-03-12")              # Auto-parse
Date.strptime("12/03/2026", "%d/%m/%Y")  # Explicit format

Formatting Dates

time = Time.now
time.strftime("%Y-%m-%d")    # => "2026-03-12"
time.strftime("%H:%M:%S")    # => "20:30:00"

Date Calculations

time = Time.now
time + 86400      # 1 day later
time - 86400      # 1 day ago

# Difference in seconds
later = time + 3600
later - time      # => 3600.0

Common Recipes

Age calculation

def age(birthdate)
  today = Date.today
  age = today.year - birthdate.year
  age -= 1 if today.yday < birthdate.yday
  age
end

Unix timestamp

time = Time.now
time.to_i              # seconds since 1970
Time.at(1700000000)    # convert back

Filename timestamps

Time.now.strftime("%Y%m%d_%H%M%S")  # => "20260312_203000"
File.mtime("example.txt")

See Also

• Array#join — Formatting arrays with separators
• JSON — Parsing JSON timestamps