About

Twitch caps ingest at 8500 kbps, but pushing that ceiling without matching your resolution, encoder, and content type produces either a muddy stream or dropped frames. The relationship between pixel count, frame rate, and perceptual quality is non-linear. A 1080p60 fast-action game at 6000 kbps with NVENC will exhibit macro-blocking that a 900p60 stream at the same bitrate avoids entirely. This calculator derives the recommended video bitrate from the product of pixel area, frame rate, a motion complexity coefficient M, and an encoder-specific bits-per-pixel factor BPP, then validates the result against Twitch's hard limit and your measured upload speed.

The tool assumes CBR (Constant Bit Rate) encoding, which Twitch recommends over VBR for ingest stability. Results approximate real-world quality under standard keyframe interval (2 s) and "veryfast" / "P4" presets. Slower presets improve quality at the same bitrate but demand more CPU/GPU. If your upload bandwidth sits below 1.5× the calculated total bitrate, expect instability during bitrate spikes.

Formulas

The recommended video bitrate is derived from resolution, frame rate, content motion, and encoder efficiency:

B_video = W × H × FPS × M × BPP1000

Where W = output width in pixels, H = output height in pixels, FPS = frames per second (30 or 60), M = motion complexity factor (Low = 0.07, Medium = 0.10, High = 0.14), and BPP = bits per pixel per frame, varying by encoder (x264 veryfast ≈ 0.10, NVENC P4 ≈ 0.12, AMF ≈ 0.12).

B_total = B_video + B_audio

The minimum required upload speed includes a safety margin to absorb bitrate spikes during scene changes:

Upload_min = B_total × 1.4

If B_video exceeds the Twitch ingest cap of 8500 kbps (minus audio), the tool clamps the value and flags that the selected resolution/FPS combination is not viable without transcoding artifacts.

Reference Data

Resolution	Pixels	Low Motion kbps	Medium Motion kbps	High Motion kbps	Twitch Viable
640×360 (360p)	230,400	400	700	1200	Yes
854×480 (480p)	409,920	700	1200	2000	Yes
960×540 (540p)	518,400	900	1500	2500	Yes
1024×576 (576p)	589,824	1000	1800	2800	Yes
1280×720 (720p)	921,600	1500	2500	4000	Yes
1366×768 (768p)	1,049,088	1800	3000	4500	Yes
1600×900 (900p)	1,440,000	2500	4000	6000	Yes
1920×1080 (1080p)	2,073,600	3500	5500	8000	Marginal
2560×1440 (1440p)	3,686,400	6000	9000	14000	No (exceeds cap)
3840×2160 (4K)	8,294,400	13000	20000	35000	No (exceeds cap)
Values at 30 FPS with x264 veryfast. Multiply ×1.5 for 60 FPS. NVENC/AMF values ~10-15% higher for equivalent quality.

Frequently Asked Questions

Twitch's ingest servers are optimized for Constant Bit Rate. VBR creates unpredictable bandwidth spikes that can exceed your upload headroom or the 8500 kbps cap momentarily, causing dropped frames. CBR ensures a steady data flow. The transcode pipeline also produces more consistent quality segments for viewers on lower quality options when the source is CBR.

Slower presets (e.g., x264 'medium') spend more CPU time on motion estimation and reference frames, producing better quality at the same bitrate. A "medium" preset at 4500 kbps can match a "veryfast" preset at 6000 kbps visually. However, slower presets can cause encoding lag if your CPU cannot keep up in real-time. This calculator assumes "veryfast" for x264 and "P4" (medium) for NVENC as safe defaults.

Twitch silently drops packets above the ingest cap. Your OBS will report 0% dropped frames locally, but viewers see macro-blocking, freezes, and buffering. The stream may also be flagged by Twitch's infrastructure and disconnected during peak load. Always stay at or below 8500 kbps total (video + audio combined).

Without guaranteed transcoding (Partner status), viewers with slower connections must watch your source quality. A 1080p60 stream at 6000 kbps forces viewers to maintain 6+ Mbps download. A 900p60 stream at 4500 kbps is accessible to more viewers and actually looks sharper because fewer pixels compete for available bits. The bits-per-pixel ratio improves significantly at 900p.

The calculator applies a 1.4× safety multiplier. This accounts for TCP/IP overhead, encoding spikes during high-motion scene changes, and your ISP's upload variance. If your speed test shows 10 Mbps upload, your stable usable bandwidth is closer to 7-8 Mbps under sustained load. Test with a Twitch bandwidth test or stream to a private channel for 30 minutes during peak ISP hours.

Audio consumes a fixed portion of your total budget. At 160 kbps AAC stereo, audio quality is transparent for voice and game sound. Going to 320 kbps gains negligible perceptual quality for streaming (lossy transcode negates it) but steals 160 kbps from video. For music-focused streams, 192-256 kbps is a reasonable compromise. Never go below 96 kbps - compression artifacts become audible in voice.