What is Intl.NumberFormat and why use it instead of regex?

Intl.NumberFormat is the browser's built-in, standards-based number formatter (part of the ECMAScript Internationalization API). It knows that German groups with dots and decimals with commas, that French uses a narrow no-break space, that Indian English groups as 12,34,567 (lakhs), and that Japanese yen has no decimal places. Rolling your own with string padding and regex breaks the moment you hit a locale you didn't test. This tool drives every grouping, currency, percent and compact output through Intl.NumberFormat, so what you copy matches what real users in that region expect.

What is the difference between English "K/M/B" and Chinese "万/亿" compact numbers?

English compact notation groups by powers of one thousand: K = 10^3, M = 10^6, B = 10^9. Chinese (and Japanese/Korean) groups by powers of ten thousand: 万 = 10^4, 亿 = 10^8. So 12,000 is "12K" in English but "1.2万" in Chinese, and 150,000,000 is "150M" in English but "1.5亿" in Chinese. They are not interchangeable — converting "1M" to Chinese is "100万", not "1万". This tool renders compact form in whichever language you have selected, so you never hand a Chinese reader a "K" they have to mentally re-base.

Why do some results look slightly off, like 0.1 + 0.2 showing extra digits?

JavaScript numbers are IEEE-754 doubles, so values like 0.1 cannot be stored exactly and long chains of arithmetic can surface tiny rounding artifacts (the classic 0.1 + 0.2 = 0.30000000000000004). This tool formats whatever value you give it; it does not do exact decimal arithmetic. For display, set a fixed number of decimal places to hide the artifact. For money you must keep exact, store and compute in integer minor units (cents) and only format at the very end — which is exactly what the currency row here does when you pin the decimals.

How does reverse parsing decide if a comma is a decimal point or a thousands separator?

If both '.' and ',' appear, the one that comes last is treated as the decimal separator — so 1,234.56 is read US-style and 1.234,56 is read European-style. If only commas appear, a single comma followed by 1 or 2 digits is treated as a decimal (1,5 → 1.5), while 3-digit groups are treated as thousands (1,234 → 1234). Currency symbols, percent signs, plain/narrow/no-break spaces, and full-width or Arabic-Indic digits are normalised before parsing. A trailing percent divides the result by 100.

Do I need this for Chinese uppercase amounts like 壹贰叁?

No — that is a different job. This tool handles numeric display formats (grouping, currency symbols, compact, scientific). For the formal Chinese capital characters used on checks and invoices (壹贰叁肆 and 元角分整 amount form), use the dedicated Chinese Numeric Converter, which is linked at the bottom of this tool.

Build a locale-correct invoice total without guessing separators

You are wiring an invoice template that ships to US, German, and French customers. Type the amount once (say 1234567.89), pick the currency, and read all three currency rows by switching the grouping locale: $1,234,567.89, 1.234.567,89 €, and 1 234 567,89 € with the right space. Copy each into your i18n message file. You stop shipping the US-comma version to a German customer who reads it as a decimal.

Sanity-check a "1.2M" dashboard label against the raw number

A stakeholder asks "is that compact label actually 1.2 million or 1.2 billion?" Paste 1200000 into the input, look at the Compact row (1.2M) and the Scientific row (1.2000e+6) side by side. You confirm the magnitude in two seconds instead of squinting at the dashboard and counting zeros. Flip the language to zh and you also see the 1.2万 / 亿 grouping a Chinese stakeholder would expect.

Convert a raw byte count into a human file size for a log line

Your service logs payload sizes in raw bytes and a teammate asks how big "1073741824" really is. Paste it, read the Byte size row: 1 GB. Paste 1536 and get 1.5 KB. Because it uses the binary 1024 base, the numbers match what your OS file manager and most server tooling show, so the log annotation you write is the one ops will recognise.

Parse a number a user pasted from a foreign spreadsheet

A support ticket includes the value "1.234.567,89" copied from a German Excel sheet, and your bug repro needs the machine number. Paste it into the input — the Parsed value row shows 1234567.89, ready to copy into a test fixture. Same for "$1,200.50", "25%" (→ 0.25), or a full-width "１２３４" pasted from a CJK form.

Pick the right notation for a scientific figure caption

You are captioning a chart axis that spans 0.0000123 to 12,345,000 and need consistent notation. Paste each end and compare the Scientific row (1.2300e-5, 1.2345e+7) against the Engineering row (12.300e-6, 12.345e+6). Engineering keeps the exponent a multiple of three so it lines up with SI prefixes (µ, M), which reads cleaner on an axis than raw scientific exponents.

Number Formatter — Grouping, Currency, Scientific, Compact, Ordinal, Bytes

One number in, every format out: thousands grouping, currency, percent, scientific, engineering, compact (K/M/万), ordinal, byte size — plus reverse parsing. 100% browser-only.

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Number (paste any format)

Examples

Thousands groupingCurrencyDecimal places

Parsed value

1234567.89

Thousands grouped

1,234,567.89

Currency

$1,234,567.89

Percent

123,456,789%

Scientific

1.2346e+6

Engineering

1.235e+6

Compact

1.23M

Ordinal

—

Byte size

1.18 MB

Need 中文大写 (壹贰叁 / 金额大写)? Chinese Numeric Converter

What this tool does

Paste one number and instantly read it back in every format you actually ship: thousands-grouped in five locale styles (1,234,567 US / 1.234.567 DE / 1 234 567 FR / 12,34,567 Indian / Chinese), currency in eight currencies via the browser's own Intl.NumberFormat (so $1,234.50, ¥1,000 with no decimals, and 1.234,56 € all come out the way each region writes them), percent, scientific (1.5000e+6), engineering notation with the exponent locked to a multiple of three (12.345e+3), compact (1.2M in English, 1.2万 in Chinese), English ordinals (1st, 22nd, 113th) and the Chinese "第N" form, and binary byte size (1536 → 1.5 KB, 1073741824 → 1 GB). It works in reverse too: paste "1.234.567,89" or "$1,200.50" or "25%" or "1.5e6" or full-width "１２３４" and it strips the formatting back to a plain machine number you can copy into code. Decimal places are adjustable (auto or 0–8 fixed), every row has its own copy button, and your locale and currency preferences are remembered between visits. The input and options live in the URL so a share link reopens on the exact same number. All math is plain JavaScript running in your tab — nothing is uploaded.

Tool details

Input: Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Number Formatter fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Build a locale-correct invoice total without guessing separators
You are wiring an invoice template that ships to US, German, and French customers. Type the amount once (say 1234567.89), pick the currency, and read all three currency rows by switching the grouping locale: $1,234,567.89, 1.234.567,89 €, and 1 234 567,89 € with the right space. Copy each into your i18n message file. You stop shipping the US-comma version to a German customer who reads it as a decimal.
Sanity-check a "1.2M" dashboard label against the raw number
A stakeholder asks "is that compact label actually 1.2 million or 1.2 billion?" Paste 1200000 into the input, look at the Compact row (1.2M) and the Scientific row (1.2000e+6) side by side. You confirm the magnitude in two seconds instead of squinting at the dashboard and counting zeros. Flip the language to zh and you also see the 1.2万 / 亿 grouping a Chinese stakeholder would expect.
Convert a raw byte count into a human file size for a log line
Your service logs payload sizes in raw bytes and a teammate asks how big "1073741824" really is. Paste it, read the Byte size row: 1 GB. Paste 1536 and get 1.5 KB. Because it uses the binary 1024 base, the numbers match what your OS file manager and most server tooling show, so the log annotation you write is the one ops will recognise.
Parse a number a user pasted from a foreign spreadsheet
A support ticket includes the value "1.234.567,89" copied from a German Excel sheet, and your bug repro needs the machine number. Paste it into the input — the Parsed value row shows 1234567.89, ready to copy into a test fixture. Same for "$1,200.50", "25%" (→ 0.25), or a full-width "１２３４" pasted from a CJK form.
Pick the right notation for a scientific figure caption
You are captioning a chart axis that spans 0.0000123 to 12,345,000 and need consistent notation. Paste each end and compare the Scientific row (1.2300e-5, 1.2345e+7) against the Engineering row (12.300e-6, 12.345e+6). Engineering keeps the exponent a multiple of three so it lines up with SI prefixes (µ, M), which reads cleaner on an axis than raw scientific exponents.

Common pitfalls

Treating compact "1M" as interchangeable across languages. English M is 10^6, but if you naively show the same "M" to a Chinese reader they expect 万/亿 grouping. Switch the tool language before copying so 1,200,000 comes out as "1.2M" for English and "120万" for Chinese — not a "K/M" a Chinese user has to re-base in their head.
Formatting money for storage. The currency row is for display only. Never store a formatted string like "$1,234.50" or do math on the floating-point value for money — keep integer minor units (cents) and format only at the edge. The decimal artifacts you may see come from IEEE-754 doubles, not from the formatter.
Assuming a comma is always a thousands separator when parsing. "1,5" pasted from a European locale means 1.5, not 15. This tool uses the last-separator rule and group-length heuristics, but if your source is purely "1,234" it is genuinely ambiguous between 1234 and 1.234 — confirm the source locale rather than trusting the parse blindly for a single 3-digit comma group.

Privacy

Every format (grouping, currency, percent, scientific, engineering, compact, ordinal, byte size) and the reverse parser are plain JavaScript that runs in your browser tab via the built-in Intl API. No number you type is uploaded, logged, or analysed. The one caveat: the number and your locale/currency choices are encoded in the shareable URL query string (e.g. ?n=1234567.89), so if you paste a "share link" containing a sensitive figure (a salary, an unreleased revenue number) into Slack or email, the destination server's access log will record it. For sensitive values, copy the formatted result manually instead of sharing the URL.

FAQ

Tool combos

Folks in your role tend to reach for these alongside this tool.

Browse all tools for this role

Number Formatter — Grouping, Currency, Scientific, Compact, Ordinal, Bytes

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Number Formatter fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Build a locale-correct invoice total without guessing separators

Sanity-check a "1.2M" dashboard label against the raw number

Convert a raw byte count into a human file size for a log line

Parse a number a user pasted from a foreign spreadsheet

Pick the right notation for a scientific figure caption

Common pitfalls

Privacy

FAQ

Unit Converter

Chinese Numeric Converter

Scientific Notation Converter

Percentage Calculator

Scientific Calculator

Currency Converter

Number Base Converter

24-Point Solver & Game

555 Timer Calculator

A1C to Blood Glucose Calculator

Add Days to Date Calculator

Age Calculator