タイムゾーン変換

Why spelling out numbers still matters

Turning 1234 into "one thousand two hundred thirty-four" might look like a school exercise, but it solves real problems. Spelled-out numbers cannot be altered the way a digit can — adding a zero to "$100" is trivial, but rewriting "one hundred dollars" is not — which is why checks and contracts use words. Words are also what a screen reader pronounces, what an invoice prints alongside the figures, and what style guides demand at the start of a sentence. This converter spells any number in English in three formats: cardinal, ordinal, and US-dollar currency, instantly as you type.

How the conversion is built, group by group

English number names follow the short scale, where each new name covers three more digits: thousand, million, billion, trillion. The converter exploits this by chopping the number into three-digit groups from the right and naming each group, then appending its scale word. Within a group of three it has just a few rules: numbers below twenty have unique names (eleven, twelve, … nineteen), tens from twenty up combine a tens word with a ones word joined by a hyphen (forty-seven), and hundreds prefix the digit with "hundred". Assemble the groups and you have the full name. The tool handles values up to the trillions and prefixes "negative" for numbers below zero.

A worked example

Enter 1,234,567 (commas are ignored). The converter splits it into the groups 1 | 234 | 567. The first group is "one" followed by its scale word "million"; the second is "two hundred thirty-four" followed by "thousand"; the third is "five hundred sixty-seven" with no scale word. Concatenated, the result is "one million two hundred thirty-four thousand five hundred sixty-seven". Switch to currency mode and enter 42.75 instead: the whole part becomes "forty-two dollars", the two decimal digits become "seventy-five cents", joined as "forty-two dollars and seventy-five cents".

The three modes

Cardinal answers "how many"; ordinal answers "which position" (first, second, third). The ordinal converter takes the cardinal words and adjusts only the final word using English's irregular rules: one→first, two→second, three→third, five→fifth, eight→eighth, nine→ninth, twelve→twelfth, words ending in "y" become "-ieth" (twenty→twentieth), and everything else simply takes "th" (six→sixth). Currency splits at the decimal point: the integer part is dollars and the first two decimals are cents, rounded, with correct singular and plural ("one dollar" but "two dollars").

Practical use cases

• Writing checks. Copy the currency output straight onto the "amount in words" line so the figure cannot be tampered with.
• Legal and formal documents. Contracts and resolutions often require both the numeral and its spelled-out form for clarity and fraud resistance.
• Accessibility and narration. Generate the exact text a voiceover or screen reader should say for a number.
• Teaching and learning. Check that students spell large numbers and ordinals correctly, including the tricky irregular cases.

Common mistakes

• Entering a decimal in cardinal or ordinal mode. Those modes require whole integers; a value like 3.5 is rejected. Use currency mode for amounts with cents, or round to a whole number first.
• Forgetting the output is lowercase. The tool writes "one hundred", not "One Hundred". Capitalize the first letter yourself to suit your style guide — legal text often wants the leading word capitalized.
• Expecting British "and". This converter uses the American style without "and" between hundreds and tens in plain numbers ("one hundred twenty"), reserving "and" to join dollars and cents. British usage ("one hundred and twenty") differs.
• Exceeding the range. Values are spelled up to the trillions; beyond that, English lacks widely agreed common names and the tool is not designed to go further.

Privacy

The conversion is pure text processing in your browser. No number you enter is sent to or stored on a server, so even sensitive amounts stay on your device, and the tool works with no internet connection.