apostilbs (asb) to nits (nt) conversion

1 asb = 0.3183099 ntnt → asb
Formula
1 asb = 0.3183099 nt

Understanding apostilbs to nits Conversion

The apostilb (asb) is a metric luminance unit equal to 1/π cd/m², rooted in perfectly diffusing surfaces. The nit (nt) is simply the common name for the candela per square metre, the SI luminance unit used to rate display, TV, and smartphone screen brightness. Since one nit equals one cd/m², converting apostilbs to nits uses the same 1/π factor and is the practical way to express legacy luminance values in modern display terms.

Conversion Formula

1 asb=0.318310 nt1\ \text{asb} = 0.318310\ \text{nt}

To convert apostilbs to nits, multiply by this factor:

nt=asb×0.3183099\text{nt} = \text{asb} \times 0.3183099

Step-by-Step Example

Convert 25 apostilbs to nits.

nt=25×0.3183099=7.95775 nt\text{nt} = 25 \times 0.3183099 = 7.95775\ \text{nt}

How to Convert apostilbs to nits

Put legacy apostilb luminance on the modern nit scale used for screen brightness.

  1. Start with apostilbs: Take the luminance value, for example 25 asb.
  2. Multiply by 0.3183099: The 1/π apostilb-to-nit factor.
  3. Read the result: 25 × 0.3183099 = 7.95775 nits.
  4. Reverse-check: Multiply nits by 3.141593 (π) to recover apostilbs.

apostilbs to nits conversion table

apostilbs (asb)nits (nt)
00
10.3183099
20.6366198
30.9549297
41.27324
51.591549
61.909859
72.228169
82.546479
92.864789
103.183099
154.774648
206.366198
257.957747
309.549297
4012.7324
5015.91549
6019.09859
7022.28169
8025.46479
9028.64789
10031.83099
15047.74648
20063.66198
25079.57747
30095.49297
400127.324
500159.1549
600190.9859
700222.8169
800254.6479
900286.4789
1000318.3099
2000636.6198
3000954.9297
40001273.24
50001591.549
100003183.099
250007957.747
5000015915.49
10000031830.99
25000079577.47
500000159154.9
1000000318309.9

What is the apostilb?

The apostilb is an obsolete unit of luminance once used to describe the brightness of diffusely reflecting or emitting surfaces. It belongs to a family of "1/π" luminance units designed to simplify calculations for perfectly diffuse (Lambertian) surfaces.

Definition

One apostilb is defined as one lumen per square metre emitted from a perfectly diffusing surface, which equals 1/π candela per square metre.

1 asb=0.318310 cd/m21\ \text{asb} = 0.318310\ \text{cd/m}^2

Exactly, 1 asb=1π cd/m2=10−4 lambert1\ \text{asb} = \frac{1}{\pi}\ \text{cd/m}^2 = 10⁻⁴\ \text{lambert}.

Origin and History

The apostilb was part of an early-20th-century set of photometric units (alongside the lambert and foot-lambert) built around the factor 1/π so that a Lambertian surface illuminated to a given number of lux would have a numerically equal luminance. The prefix "apo-" distinguished it from the stilb.

Law and Notable Facts

The apostilb is not an SI unit and is now essentially obsolete, replaced by the candela per square metre. Its defining convenience was that a perfect diffuser receiving an illuminance of one lux has a luminance of exactly one apostilb.

Real-World Examples and Conversions

  • A white matte surface at 1 lux illuminance: about 1 apostilb.
  • 1 asb=1π cd/m2≈0.318310 cd/m21\ \text{asb} = \frac{1}{\pi}\ \text{cd/m}^2 \approx 0.318310\ \text{cd/m}^2.
  • 1 cd/m2=π apostilbs≈3.14159 asb1\ \text{cd/m}^2 = \pi\ \text{apostilbs} \approx 3.14159\ \text{asb}.
  • 104 apostilbs=1 lambert≈3183.10 cd/m210⁴\ \text{apostilbs} = 1\ \text{lambert} \approx 3183.10\ \text{cd/m}^2.

What is the nit?

The nit is a unit of luminance used to describe the brightness of light emitted from or reflected by a surface, most familiarly the screens of televisions, monitors, and phones. It is numerically identical to the SI unit, the candela per square metre.

Definition

One nit is exactly one candela per square metre, the luminous intensity of one candela spread over one square metre of projected surface area.

1 nt=1 cd/m21\ \text{nt} = 1\ \text{cd/m}^2

The two units are interchangeable: 1 nt=1 cd/m2=1 lm/(m2⋅sr)1\ \text{nt} = 1\ \text{cd/m}^2 = 1\ \text{lm}/(\text{m}^2 \cdot \text{sr}).

Origin and History

The name "nit" derives from the Latin nitere, meaning "to shine," and came into use in the mid-20th century as a convenient shorthand for the candela per square metre. It remains popular in the display and photometry industries.

Law and Notable Facts

The nit is not an official SI unit name but is exactly equal to the SI candela per square metre, so it carries no ambiguity. Display manufacturers routinely quote peak brightness in nits, with high-dynamic-range (HDR) televisions marketed at 1000 nits or more.

Real-World Examples and Conversions

  • Standard SDR television: about 100 nits reference white.
  • Modern OLED and LCD monitors: 250–600 nits.
  • HDR displays: peak highlights of 1000–4000 nits.
  • 1 nt=1 cd/m2=10−4 stilb≈3.14159 apostilbs1\ \text{nt} = 1\ \text{cd/m}^2 = 10⁻⁴\ \text{stilb} \approx 3.14159\ \text{apostilbs}.

Frequently Asked Questions

How many nits are in one apostilb?

One apostilb equals 0.3183099 nits, which is 1/π, because a nit is identical to one candela per square metre and the apostilb carries the factor of π.

How do I convert apostilbs to nits?

Multiply the apostilb value by 0.3183099. For example, 40 apostilbs equals 40 × 0.3183099 = 12.73 nits.

How do I convert nits back to apostilbs?

Multiply nits by 3.141593 (π). So a 400-nit display equals about 1,257 apostilbs.

Is a nit the same as a candela per square metre?

Yes; the nit is just the informal name for cd/m², so apostilb-to-nit and apostilb-to-cd/m² conversions use the identical 0.3183099 factor.

Why would I convert to nits?

Screen brightness for phones, monitors, and TVs is quoted in nits, so converting apostilbs to nits places older luminance data on the same scale as display specifications.

People also convert

asb to cd/m2asb to sbasb to Lasb to fL

Complete apostilbs conversion table

asb
UnitResult
candelas per square metre (cd/m2)0.3183099 cd/m2
nits (nt)0.3183099 nt
stilbs (sb)0.00003183099 sb
lamberts (L)0.0001 L
foot-lamberts (fL)0.09290304 fL

Luminance conversions