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String#rjust 

str.rjust(width, padstr = ' ') -> string
Returns: String · Updated March 16, 2026 · String Methods
strings padding formatting alignment

The .rjust method pads a string to a specified width on the left side, placing the original string on the right. By default, it uses spaces for padding, but you can specify any character or string. This is useful for formatting numeric output, creating fixed-width tables, or aligning text to the right in terminal applications.

Syntax

str.rjust(width)           # Pad with spaces (default)
str.rjust(width, padstr)   # Pad with custom string

Parameters

ParameterTypeDescription
widthIntegerThe total width of the resulting padded string
padstrStringThe string to use for padding (default is space)

Worked Examples

Example 1: Basic right-justification with spaces

text = "Ruby"

puts text.rjust(10)
# Output: "      Ruby"

When the total width is larger than the string, Ruby adds padding to the left side.

puts "Hi".rjust(10)     # "        Hi"
puts "Hello".rjust(10)  # "     Hello"
puts "Ruby".rjust(10)   # "      Ruby"

Example 2: Using custom padding characters

puts "Ruby".rjust(10, "*")   # "******Ruby"
puts "Hi".rjust(10, "-")     # "--------Hi"
puts "X".rjust(5, "=")       # "====X"

You can use multi-character strings for padding:

puts "Yo".rjust(10, "._.")   # "._._._._.Yo"

Example 3: Creating formatted numeric tables

numbers = [7, 42, 128, 1024, 4096]

numbers.each do |num|
  puts num.to_s.rjust(5)
end

# Output:
#     7
#    42
#   128
#  1024
#  4096

Example 4: Right-aligning variable-width data

labels = ["Name:", "Email:", "Status:"]
values = ["john", "john@example.com", "active"]

labels.zip(values).each do |label, value|
  puts "#{value.rjust(20)}: #{label}"
end

# Output:
#                john: Name:
#     john@example.com: Email:
#                active: Status:

Example 5: When width is less than string length

If the specified width is less than or equal to the string’s length, Ruby returns the original string unchanged.

puts "Ruby".rjust(2)   # "Ruby" (no padding needed)
puts "Ruby".rjust(4)   # "Ruby" (exact fit)

Common Patterns

Building CLI tables with right-aligned columns

data = [
  ["Item", "Qty", "Price"],
  ["Apple", "5", "2.50"],
  ["Banana", "12", "1.80"],
  ["Cherry", "100", "0.50"]
]

# Right-align numeric columns
data.each do |row|
  puts row[0].ljust(10) + row[1].rjust(5) + row[2].rjust(10)
end

# Output:
# Item      |    5|      2.50
# Banana    |   12|      1.80
# Cherry    |  100|       0.50

Formatting file sizes

sizes = [512, 1024, 1536, 2048, 4096]

sizes.each do |bytes|
  puts "#{bytes.to_s.rjust(6)} bytes"
end

# Output:
#    512 bytes
#   1024 bytes
#   1536 bytes
#   2048 bytes
#   4096 bytes

Creating indented code blocks

code = ["def hello", "  puts 'World'", "end"]

code.each do |line|
  puts line.rjust(line.length + 4)
end

# Output:
#     def hello
#       puts 'World'
#         end

Edge Cases

Empty strings and special characters

puts "".rjust(5)        # "     "
puts " ".rjust(5)       # "     " (single space becomes 5)
puts "\t".rjust(5)      # tabs also pad correctly
puts "日本語".rjust(10) # "      日本語" (Unicode works)

Padding with empty string

puts "Ruby".rjust(10, "")  # Raises ArgumentError: zero width padding

Negative width

puts "Ruby".rjust(-5)   # Raises ArgumentError: negative string size

See Also