What is scientific notation?

Scientific notation writes a number as a coefficient from 1 up to (but not including) 10, times a power of 10: a × 10ⁿ. The speed of light, 299,792,458 m/s, is 2.99792458 × 10⁸ m/s. It keeps very large and very small numbers short and makes the number of significant digits obvious.

What is E notation, and how is it different?

E notation is scientific notation typed on one line, the way calculators and spreadsheets show it: the E stands for “times ten to the power”. 6.022E23 means 6.022 × 10²³ and 1.6E-19 means 1.6 × 10⁻¹⁹. You can type either form into the converter, as well as 6.022 × 10^23 or 6.022*10^23.

What is engineering notation?

Engineering notation is scientific notation with the power of 10 restricted to multiples of 3, so the coefficient can run from 1 to 999.999…. That matches the SI prefixes: 12,500 is 12.5 × 10³, or 12.5 kilo-units, and 0.00000000000000000016 is 160 × 10⁻²¹, zepto. Beyond 10³⁰ and below 10⁻³⁰ there is no SI prefix.

How do I count significant figures?

Every non-zero digit counts, and so do zeros between them. Leading zeros never count, because they only place the decimal point: 0.00123 has 3. Trailing zeros count when there is a decimal point (1200. has 4) and are treated as placeholders when there is not (1200 has 2). The power of 10 never changes the count, so 1.200 × 10³ has 4.

How does the converter round to significant figures?

It rounds the digit string itself, half up: if the first dropped digit is 5 or more the last kept digit goes up by one. 0.000123456 to 3 figures is 1.23 × 10⁻⁴. A carry can raise the exponent: 9.996 to 3 figures is 1.00 × 10¹, written 10.0. Nothing goes through floating point, so a value such as 1.005 rounds to 1.01 the way the digits say, not 1.00 as a binary double would.

Why does the result show trailing zeros I did not type?

When you choose a number of significant figures larger than the digits you typed, the converter pads with zeros: 1.5 to 4 figures is 1.500 × 10⁰. Those zeros are how a measurement shows its precision. Choose Auto to keep exactly the digits you gave.

How do I write a very small number like 1e-30 in full?

Put the digit after a decimal point and as many zeros as the power says, minus one: 1 × 10⁻³⁰ is 0.000000000000000000000000000001. The converter builds the text from the digits and the exponent, so it never stops at a few places the way a floating-point display does.

How is a number said in words?

The converter picks the power of a thousand that leaves 1 to 999 in front: 6.022 × 10²³ is about 602 sextillion (short scale, where a billion is 10⁹), and 1.6 × 10⁻¹⁹ is 160 sextillionths. The coefficient is rounded to three figures, so “about” appears when digits were dropped. Names run up to vigintillion (10⁶³); beyond that only the order of magnitude is given.

What input forms does it accept?

Plain numbers (1234.5, .5, −42), numbers with thousands separators (1,234,567 or 1 234 567), a decimal comma (3,5), E notation (6.022e23, 1.6E-19) and written-out notation (6.022 × 10^23, 6.022 x 10^23, 6.022*10^23, 6.022 × 10²³, or just 10^5). Up to 100 digits and powers of 10 from −1000 to 1000.

Is my number sent anywhere?

No. The conversion runs in your browser. The number you type stays on your device, and the page only records that the tool was used, never what you entered.

Scientific Notation Converter

To write a number in scientific notation, move the decimal point until one non-zero digit is left in front of it, and use the number of places you moved it as the power of 10: 602,200,000,000,000,000,000,000 = 6.022 × 10²³ (6.022E23 in E notation) and 0.00000000000000000016 = 1.6 × 10⁻¹⁹. Moving the point left gives a positive power, right gives a negative one. Engineering notation uses powers that are multiples of 3, 602.2 × 10²¹ for the first number, which is zetta in SI prefixes. In words, the first number is about 602 sextillion. Type a number in any form, with or without commas, or already in E or × 10^n notation, pick how many significant figures to keep, and the converter writes it out exactly, with no floating-point rounding.

Updated 2026-10-03Runs in your browser: nothing you enter is uploadedHow this tool works

6.022e23 =

6.022 × 10²³

Your number has 4 significant figures. All are kept.

Plain text: 6.022 × 10^23
E notation: 6.022E23
Engineering notation: 602.2 × 10²¹
SI prefix: zetta (Z, 10²¹)
Standard form: 602,200,000,000,000,000,000,000
In words: about 602 sextillion
Order of magnitude: 10²³
Sig figs in your number: 4
Sig figs shown: 4

Why that many significant figures

Zeros between non-zero digits always count.
The power of 10 in E or scientific notation never changes the count.

SI prefixes from quecto to quetta

Each prefix multiplies a unit by a power of 10 that is a multiple of 3, the same powers engineering notation uses. The example column expresses a real quantity in that prefix, computed by shifting the decimal point.
Prefix	Symbol	Power of 10	Factor	Example
quetta	Q	10³⁰	one nonillion	Mass of Jupiter ≈ 1.898 Qg
ronna	R	10²⁷	one octillion	Mass of Earth ≈ 5.972 Rg
yotta	Y	10²⁴	one septillion	Mass of the Moon ≈ 73.42 Yg
zetta	Z	10²¹	one sextillion	Mass of Earth’s atmosphere ≈ 5.15 Zg
exa	E	10¹⁸	one quintillion	One kiloparsec ≈ 30.86 Em
peta	P	10¹⁵	one quadrillion	One light-year ≈ 9.461 Pm
tera	T	10¹²	one trillion	Distance from the Sun to Neptune ≈ 4.495 Tm
giga	G	10⁹	one billion	Earth–Sun distance (1 AU) ≈ 149.6 Gm
mega	M	10⁶	one million	Radius of Earth ≈ 6.371 Mm
kilo	k	10³	one thousand	A marathon ≈ 42.195 km
milli	m	10⁻³	one thousandth	Thickness of a credit card ≈ 0.76 mm
micro	µ	10⁻⁶	one millionth	Width of a red blood cell ≈ 7 µm
nano	n	10⁻⁹	one billionth	Width of a DNA double helix ≈ 2 nm
pico	p	10⁻¹²	one trillionth	Bohr radius of hydrogen ≈ 52.92 pm
femto	f	10⁻¹⁵	one quadrillionth	Radius of a gold nucleus ≈ 7 fm
atto	a	10⁻¹⁸	one quintillionth	An attosecond laser pulse ≈ 100 as
zepto	z	10⁻²¹	one sextillionth	Light crossing a hydrogen molecule ≈ 247 zs
yocto	y	10⁻²⁴	one septillionth	Mass of a proton ≈ 1.6726 yg
ronto	r	10⁻²⁷	one octillionth	Mass of an electron ≈ 0.9109 rg
quecto	q	10⁻³⁰	one nonillionth	Mass of an electron ≈ 910.9 qg

Worked examples

Each row is worked out by the converter above. Type any of these numbers to see the full set of forms.
Number	Scientific	E notation	Engineering	Standard form
299792458	2.99792458 × 10⁸	2.99792458E8	299.792458 × 10⁶	299,792,458
602,200,000,000,000,000,000,000	6.022 × 10²³	6.022E23	602.2 × 10²¹	602,200,000,000,000,000,000,000
0.00000000000000000016	1.6 × 10⁻¹⁹	1.6E-19	160 × 10⁻²¹	0.00000000000000000016
9.109e-31	9.109 × 10⁻³¹	9.109E-31	910.9 × 10⁻³³	0.0000000000000000000000000000009109
7.35E22	7.35 × 10²²	7.35E22	73.5 × 10²¹	73,500,000,000,000,000,000,000
186,000	1.86 × 10⁵	1.86E5	186 × 10³	186,000
0.00045	4.5 × 10⁻⁴	4.5E-4	450 × 10⁻⁶	0.00045
1.5 × 10^-7	1.5 × 10⁻⁷	1.5E-7	150 × 10⁻⁹	0.00000015
3.0e8	3.0 × 10⁸	3.0E8	300 × 10⁶	300,000,000
-4500	−4.5 × 10³	-4.5E3	−4.5 × 10³	−4,500

How many significant figures?

The count depends on how a number is written: zeros at the ends are the only digits in doubt.
Number	Significant figures	Rule
123	3	Non-zero digits always count.
0.00123	3	Leading zeros only place the decimal point.
1002	4	Zeros between non-zero digits count.
0.0450	3	The trailing zero after the decimal point counts; the leading zeros do not.
1200	2	Trailing zeros without a decimal point are placeholders.
1200.	4	A decimal point makes the trailing zeros count.
1.200e3	4	In E notation every digit of the mantissa counts.
100.0	4	Both trailing zeros count, because of the point.

Rounding 3.14159265 to significant figures

Rounding is half up on the digits, and a carry (9.996 to 3 figures is 10.0) moves the exponent.
Significant figures	Scientific notation	Standard form
1	3 × 10⁰	3
2	3.1 × 10⁰	3.1
3	3.14 × 10⁰	3.14
4	3.142 × 10⁰	3.142
5	3.1416 × 10⁰	3.1416
6	3.14159 × 10⁰	3.14159

How to convert a number to scientific notation

Move the decimal point after the first non-zero digit. For 602,200,000,000,000,000,000,000 the point goes after the 6, giving 6.022. For 0.00000000000000000016 it goes after the 1, giving 1.6.
Count the places you moved it. The first number needs 23 places to the left, so the power is +23: 6.022 × 10²³. The second needs 19 places to the right, so the power is −19: 1.6 × 10⁻¹⁹.
Keep the digits you can trust. Keep every significant digit and drop only the zeros that held the place. 12,500 has three significant figures at most, so it is 1.25 × 10⁴ in scientific notation; to show only two, write 1.3 × 10⁴.
For engineering notation, make the power a multiple of 3. Shift the point so the power is 3, 6, 9 and so on, leaving 1 to 3 digits before it: 12.5 × 10³ for 12,500, which is 12.5 kilo-units.
To go back, move the point the other way. A positive power moves it right, a negative power left, padding with zeros: 1 × 10⁻³⁰ is 0.000000000000000000000000000001.

Frequently asked questions

What is scientific notation?: Scientific notation writes a number as a coefficient from 1 up to (but not including) 10, times a power of 10: a × 10ⁿ. The speed of light, 299,792,458 m/s, is 2.99792458 × 10⁸ m/s. It keeps very large and very small numbers short and makes the number of significant digits obvious.
What is E notation, and how is it different?: E notation is scientific notation typed on one line, the way calculators and spreadsheets show it: the E stands for “times ten to the power”. 6.022E23 means 6.022 × 10²³ and 1.6E-19 means 1.6 × 10⁻¹⁹. You can type either form into the converter, as well as 6.022 × 10^23 or 6.022*10^23.
What is engineering notation?: Engineering notation is scientific notation with the power of 10 restricted to multiples of 3, so the coefficient can run from 1 to 999.999…. That matches the SI prefixes: 12,500 is 12.5 × 10³, or 12.5 kilo-units, and 0.00000000000000000016 is 160 × 10⁻²¹, zepto. Beyond 10³⁰ and below 10⁻³⁰ there is no SI prefix.
How do I count significant figures?: Every non-zero digit counts, and so do zeros between them. Leading zeros never count, because they only place the decimal point: 0.00123 has 3. Trailing zeros count when there is a decimal point (1200. has 4) and are treated as placeholders when there is not (1200 has 2). The power of 10 never changes the count, so 1.200 × 10³ has 4.
How does the converter round to significant figures?: It rounds the digit string itself, half up: if the first dropped digit is 5 or more the last kept digit goes up by one. 0.000123456 to 3 figures is 1.23 × 10⁻⁴. A carry can raise the exponent: 9.996 to 3 figures is 1.00 × 10¹, written 10.0. Nothing goes through floating point, so a value such as 1.005 rounds to 1.01 the way the digits say, not 1.00 as a binary double would.
Why does the result show trailing zeros I did not type?: When you choose a number of significant figures larger than the digits you typed, the converter pads with zeros: 1.5 to 4 figures is 1.500 × 10⁰. Those zeros are how a measurement shows its precision. Choose Auto to keep exactly the digits you gave.
How do I write a very small number like 1e-30 in full?: Put the digit after a decimal point and as many zeros as the power says, minus one: 1 × 10⁻³⁰ is 0.000000000000000000000000000001. The converter builds the text from the digits and the exponent, so it never stops at a few places the way a floating-point display does.
How is a number said in words?: The converter picks the power of a thousand that leaves 1 to 999 in front: 6.022 × 10²³ is about 602 sextillion (short scale, where a billion is 10⁹), and 1.6 × 10⁻¹⁹ is 160 sextillionths. The coefficient is rounded to three figures, so “about” appears when digits were dropped. Names run up to vigintillion (10⁶³); beyond that only the order of magnitude is given.
What input forms does it accept?: Plain numbers (1234.5, .5, −42), numbers with thousands separators (1,234,567 or 1 234 567), a decimal comma (3,5), E notation (6.022e23, 1.6E-19) and written-out notation (6.022 × 10^23, 6.022 x 10^23, 6.022*10^23, 6.022 × 10²³, or just 10^5). Up to 100 digits and powers of 10 from −1000 to 1000.
Is my number sent anywhere?: No. The conversion runs in your browser. The number you type stays on your device, and the page only records that the tool was used, never what you entered.

How it works

A number you type is split into its digit string and a power of ten: the digits start at the first non-zero digit, and the exponent is how far that digit sits from the decimal point, plus any exponent you typed in E or × 10^n form. Nothing is ever converted to a floating-point number, so there is no rounding error and no limit of about 15 digits. Significant figures are counted from the typed mantissa: non-zero digits and zeros between them always count, leading zeros never count, and trailing zeros count only when the number has a decimal point. Rounding to N figures looks at the digit after the Nth and rounds half up on the magnitude (so −2.5 to 1 figure is −3); a carry through all nines raises the exponent. Engineering notation floors the exponent to a multiple of 3 and moves the decimal point to match. Standard form is written from the digits and the exponent with comma groups, and the SI prefix table follows the BIPM list, which gained ronna, quetta, ronto and quecto in 2022. Words use the short scale and are rounded to three figures. Everything runs in your browser and nothing you type is sent anywhere.

Sources

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