nits (nt) to apostilbs (asb) conversion

1 nt = 3.141593 asbasb → nt
Formula
1 nt = 3.141593 asb

Understanding nits to apostilbs Conversion

The nit (nt) is the common name for the candela per square metre, the SI unit of luminance that describes how bright a surface appears — display and TV specifications quote peak brightness in nits. The apostilb (asb) is an older photometric unit of luminance equal to 1/π candela per square metre, historically used for diffusely emitting surfaces. Converting nits to apostilbs is useful when comparing modern display data against legacy photometric measurements.

Conversion Formula

1 nt=3.14159 asb1\ \text{nt} = 3.14159\ \text{asb}

To convert nits to apostilbs, multiply by this factor:

asb=nt×3.141593\text{asb} = \text{nt} \times 3.141593

Step-by-Step Example

Convert 25 nits to apostilbs.

asb=25×3.141593=78.5398 asb\text{asb} = 25 \times 3.141593 = 78.5398\ \text{asb}

How to Convert nits to apostilbs

Translate display luminance in nits into the legacy apostilb unit in one step.

  1. Note your luminance in nits: Start with the value in nt (cd/m²).
  2. Multiply by π: Multiply by 3.141593, the number of apostilbs in one nit.
  3. Report the apostilbs: The product is the equivalent luminance in asb.
  4. Worked result: 25 nt × 3.141593 = 78.5398 asb.

nits to apostilbs conversion table

nits (nt)apostilbs (asb)
00
13.141593
26.283185
39.424778
412.56637
515.70796
618.84956
721.99115
825.13274
928.27433
1031.41593
1547.12389
2062.83185
2578.53982
3094.24778
40125.6637
50157.0796
60188.4956
70219.9115
80251.3274
90282.7433
100314.1593
150471.2389
200628.3185
250785.3982
300942.4778
4001256.637
5001570.796
6001884.956
7002199.115
8002513.274
9002827.433
10003141.593
20006283.185
30009424.778
400012566.37
500015707.96
1000031415.93
2500078539.82
50000157079.6
100000314159.3
250000785398.2
5000001570796
10000003141593

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}.

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.

Frequently Asked Questions

How many apostilbs equal one nit?

One nit equals π apostilbs, approximately 3.141593 asb, because an apostilb is defined as 1/π cd/m².

How do I convert nits to apostilbs?

Multiply the nit value by 3.141593. For example, 100 nits × 3.141593 ≈ 314.159 apostilbs.

How do I convert apostilbs back to nits?

Multiply the apostilb value by 0.3183099 (which is 1/π). So 500 asb ≈ 159.15 nits.

Why does the factor involve π?

The apostilb assumes a perfectly diffuse (Lambertian) surface, where the relationship between luminance and illuminance carries a factor of π, so 1 nit corresponds to π apostilbs.

Where would I encounter apostilbs today?

They appear mostly in older lighting and photometry literature; modern display and illumination engineering uses nits (cd/m²) instead.

People also convert

nt to cd/m2nt to sbnt to Lnt to fL

Complete nits conversion table

nt
UnitResult
candelas per square metre (cd/m2)1 cd/m2
stilbs (sb)0.0001 sb
apostilbs (asb)3.141593 asb
lamberts (L)0.0003141593 L
foot-lamberts (fL)0.2918635 fL

Luminance conversions