JavaScript Number toFixed() Method

What You’ll Learn

Number.prototype.toFixed() formats a number with a fixed count of digits after the decimal point (same API as MDN Number.toFixed). It rounds when needed and pads with zeros. This tutorial covers syntax, floating-point quirks, comparisons, five examples, and try-it labs.

Introduction

Prices, scores, and form fields often need a predictable decimal layout — always two places like "12.50", not "12.5" or "12.5000001".

toFixed() builds that string for you: it rounds to the requested places and pads trailing zeros so the fractional part has a fixed length.

This page is part of JavaScript Number Methods. Related formatters include toString(), toExponential(), and toPrecision().

Understanding the toFixed() Method

Call number.toFixed() or number.toFixed(digits) on a number primitive or Number object. You always get a string; the number itself does not change.

Omit digits (or pass 0) to round to a whole number string. Pass 2 for common two-decimal display. Very large magnitudes (≥ 10²¹) may fall back to the same style as toString() and use exponential notation.

📝 Syntax

General form of Number.prototype.toFixed:

number.toFixed()
number.toFixed(digits)

Parameters

• digits (number, optional) — integer from 0 to 100. Digits after the decimal point. Default 0.

Return value

Always a string in fixed-point notation (with the large-magnitude exception noted below). Special cases:

Exceptions

• RangeError — digits < 0 or > 100.
• TypeError — called on a non-Number this value (for example a plain object).

Common patterns

(5.56789).toFixed();              // "6"
(5.56789).toFixed(2);             // "5.57"
(123).toFixed(2);                 // "123.00"
(-2.34).toFixed(1);               // "-2.3"
Number.parseFloat("1.23e+5").toFixed(2); // "123000.00"

Examples Gallery

Examples follow MDN patterns. Use View Output or Try It Yourself for each case.

(5.56789).toFixed();  // "6"

6

(5.56789).toFixed(2);  // "5.57"

5.57

(123).toFixed(2);  // "123.00"

123.00

(-2.34).toFixed(1);  // "-2.3"

-2.3

Number.parseFloat("1.23e+5").toFixed(2);  // "123000.00"

123000.00

🚀 Common Use Cases

• Price labels — show two decimals in carts and invoices (display only).
• Form inputs — normalize user numbers before showing them back.
• Tables & dashboards — align columns with a fixed fractional width.
• Scores & percentages — clip noisy floats for the UI.
• CSV / export — consistent decimal text in plain files.
• Not bank-grade math — use integer cents or a decimal library for real money rules.

📝 Notes

• Does not change the number — returns a new string.
• digits outside 0–100 throws RangeError.
• Floating-point limits can surprise you: (2.55).toFixed(1) is "2.5" in many engines.
• Very high digit counts can reveal binary fraction noise (see MDN’s (0.3).toFixed(50) example).
• Magnitudes ≥ 10²¹ may use exponential notation like toString().
• For locale currency symbols and grouping, prefer toLocaleString() / Intl.NumberFormat.

💡 Best Practices