HDR Video: PQ, HLG and the Numbers

Updated October 2026

What a PQ code value means in nits, where reference white sits, how HDR10, HDR10+ and Dolby Vision differ, and what YouTube and Netflix expect when you deliver HDR.

HDR Formats, Bit Depth and Transfer Functions

HDR Formats

HDR10

PQ, to 10,000 nits

10-bit, BT.2020, static metadata (ST 2086 plus MaxCLL and MaxFALL); usually mastered at 1,000 nits

HDR10+

PQ, to 10,000 nits

HDR10 plus scene-by-scene metadata (SMPTE ST 2094-40); plays as HDR10 on displays without HDR10+

Dolby Vision

PQ or HLG

Dynamic metadata from a Dolby Vision grade; mastered up to 12-bit, commonly on 1,000- or 4,000-nit displays

HLG

Relative signal

Hybrid Log-Gamma (ARIB STD-B67, ITU-R BT.2100), no metadata; used for broadcast and live

Bit Depth

8-bit

256 codes

SDR delivery; video range uses 16–235. Too coarse for PQ or HLG

10-bit

1,024 codes

The HDR minimum (BT.2100); video range is 64–940. HDR10 and HLG

12-bit

4,096 codes

Allowed by BT.2100; video range is 256–3,760. Used for Dolby Vision masters

16-bit half float

Linear light

OpenEXR for VFX and grading; not a delivery format

Transfer Functions

BT.1886

Gamma 2.4

The SDR display curve for Rec. 709 (BT.709 itself defines the camera curve)

PQ (ST 2084)

Absolute

Each code value is a fixed luminance, 0 to 10,000 nits: HDR10, HDR10+, Dolby Vision

HLG (BT.2100)

Relative

Scaled to the display's peak, like SDR; used with the Rec. 2020 gamut

Camera log

Logarithmic

ARRI LogC, Sony S-Log3, Canon Log: capture curves, converted to PQ or HLG in the grade

PQ Levels at a Glance

Because PQ is absolute, these values hold on any PQ display. Computed from the ST 2084 curve; video (narrow) range is what most files and scopes use, full range is what some grading tools show.

Nits (cd/m²)	PQ signal	10-bit video range	10-bit full range
0.005	1.5%	77	15
1	15.0%	195	153
26 (18% grey, BT.2408)	38.0%	397	389
100 (SDR peak white)	50.8%	509	520
203 (HDR reference white)	58.1%	573	594
1,000	75.2%	723	769
4,000	90.3%	855	923
10,000	100%	940	1,023

HDR Calculations

PQ Code Value to Nits

PQ is absolute: a code value means the same luminance on every display, whatever the mastering peak. Convert with the SMPTE ST 2084 EOTF.

Formula:

Nits = 10,000 × (max(E^(1/m2) - c1, 0) ÷ (c2 - c3 × E^(1/m2)))^(1/m1), with m1 = 0.1593, m2 = 78.84, c1 = 0.8359, c2 = 18.85, c3 = 18.69

Examples:

75% PQ signal (HDR10, HDR10+ or Dolby Vision)

Calculation: ST 2084 EOTF at E = 0.75

Result: 983 nits

50% PQ signal

Calculation: ST 2084 EOTF at E = 0.50

Result: 92 nits

Notes:

Half the PQ signal range is below 100 nits: the curve spends its codes where the eye is most sensitive
A 1,000-nit master tops out at about 75% PQ (code 723 in 10-bit video range); the codes above it are unused
E is the normalized signal: for 10-bit video range, E = (code − 64) ÷ 876

Dynamic Range in Stops

Each stop doubles the luminance, so a display's range in stops is the base-2 log of its contrast ratio.

Formula:

Dynamic range (stops) = log2(Peak luminance ÷ Black level)

Examples:

BT.2100 reference HDR display: 1,000 nits peak, 0.005 nits black

Calculation: log2(1,000 ÷ 0.005) = 17.6

Result: 17.6 stops

SDR display at 100 nits with a 1,000:1 contrast ratio (0.1-nit black)

Calculation: log2(100 ÷ 0.1) = 9.97

Result: About 10 stops

Notes:

The black level matters as much as the peak: halving it adds a stop
This is the display's range, not the camera's; a camera's latitude is measured differently
Grade HDR in a dim room: BT.2100 specifies a 5-nit neutral surround

HDR and SDR Reference Levels

Line up HDR and SDR by diffuse white, not by peak. ITU-R BT.2408 places HDR reference white at 203 nits, where SDR puts 100% white at 100 nits.

Formula:

HDR luminance (below reference white) = SDR luminance × (203 ÷ 100)

Examples:

100% SDR white (100 nits)

Calculation: 100 × 2.03 = 203 nits

Result: 203 nits, a 58% PQ signal (75% HLG)

18% grey card

Calculation: BT.2408 nominal level

Result: 26 nits, a 38% PQ signal (38% HLG)

Notes:

Graphics white (titles, lower thirds) sits at the same 203 nits, per BT.2408; full-scale white graphics on a PQ timeline are 10,000 nits
Highlights above 203 nits have no SDR equivalent: they need a roll-off curve, which is a creative choice, not a formula
The BT.2408 levels assume no camera painting or grading; treat them as starting points

HDR File Size

A compressed file's size is set by its bitrate, not its bit depth. HDR files are larger only when you encode them at a higher bitrate.

Formula:

File size (GB) = Bitrate (Mbit/s) × Duration (s) ÷ 8,000

Examples:

1 hour 4K HDR upload at 44 Mbps (low end of YouTube's HDR range)

Calculation: 44 × 3,600 ÷ 8,000 = 19.8 GB

Result: 19.8 GB

Same hour in SDR at 35 Mbps

Calculation: 35 × 3,600 ÷ 8,000 = 15.75 GB

Result: 15.75 GB: the difference comes from the bitrate

Notes:

At the same bitrate, a 10-bit HDR file and an 8-bit SDR file are the same size
YouTube recommends 44–56 Mbps for 4K HDR uploads at 24–30 fps and 66–85 Mbps at 48–60 fps, against 35–45 and 53–68 Mbps for SDR (as of October 2026)
Use a 10-bit codec: YouTube recommends VP9 Profile 2, AV1 or HEVC for HDR, and says 10-bit H.264 and ProRes work but need very high bitrates

How HLG Differs from PQ

HLG (Hybrid Log-Gamma, ARIB STD-B67 and ITU-R BT.2100) is relative, like SDR: a given signal is shown as a fraction of whatever the display can reach, so it needs no metadata and one stream can feed HDR and SDR screens. That is why broadcasters use it for live HDR.

The display adjusts its own contrast with a system gamma of 1.2 at a nominal 1,000-nit peak. For other peaks, BT.2100 gives γ = 1.2 + 0.42 × log10(peak ÷ 1,000): about 1.33 on a 2,000-nit display and 1.11 on a 600-nit one. HDR reference white sits at 75% HLG, 203 nits on a 1,000-nit display.

HDR Metadata and Tone Mapping

When a display can't reach the brightness of the master, it tone maps: it compresses the parts of the picture it can't show. Metadata tells it what it is dealing with. HDR10 has one set of values for the whole program; HDR10+ and Dolby Vision add data per scene so the display can tone map a dark scene differently from a bright one.

Metadata	Type	What it carries
ST 2086 mastering display	Static	The primaries, white point and minimum and maximum luminance of the display the grade was made on, for example P3-D65, 0.0001 to 1,000 nits.
MaxCLL	Static	Maximum Content Light Level: the brightest pixel anywhere in the program, in nits. Measured from the finished master, not typed in.
MaxFALL	Static	Maximum Frame-Average Light Level: the highest average brightness of any single frame, in nits.
HDR10+ (ST 2094-40)	Dynamic	Tone-mapping data per scene or per frame, carried in the HEVC, AV1 or VP9 stream. Displays without HDR10+ ignore it and use the HDR10 layer.
Dolby Vision	Dynamic	Per-shot analysis and trims made in a Dolby Vision grade, delivered as an XML sidecar or embedded in the file.

Delivering HDR

• YouTube: PQ or HLG, Rec. 2020 primaries, 10- or 12-bit, tagged in the file. PQ uploads should carry the mastering display and MaxCLL/MaxFALL; without them YouTube assumes a Sony BVM-X300. YouTube makes the SDR version itself, and you can supply a .cube LUT to steer it. Recommended codecs are VP9 Profile 2, AV1 and HEVC; MOV, MP4 and MKV are tested containers.
• Netflix: its Dolby Vision HDR mastering guidelines call for a P3-D65, PQ (ST 2084) monitor of at least 1,000 nits, with the Dolby Vision metadata delivered with the master. Check the current Netflix spec for your title before you grade; the Netflix delivery specs guide summarizes it.
• Apple and Amazon: Apple accepts Dolby Vision or HDR10, delivered as a second source that matches the SDR master frame for frame. Prime Video's public spec lists HDR10 only, with a matching SDR source. The Apple TV and Prime Video delivery guide covers both.
• Broadcast: HLG suits live HDR because one signal serves HDR and SDR sets; each broadcaster publishes its own HDR delivery spec.
• Always: grade the HDR first, derive the SDR from it, and QC both on reference displays.