Set up OBS

The calculator first: tell it your connection and graphics card and it tells you what to set. Below, every setting with its why, so you know what to touch when something goes wrong.

Calculator

What I'd set

Where	Value

Every setting, explained

Output

Output modeAdvanced: Simple hides half of what's below. In advanced you see everything and nothing changes by itself.
EncoderYour card's (NVENC, AMD, QuickSync); x264 only as a last resort: The card has a chip just for compressing video. x264 uses the processor, which the game needs too.
Rate controlCBR: Constant bitrate: Twitch and viewers on weak connections cope much better than with a rate that jumps around.
Bitrate6000 kbps: The most Twitch accepts on a normal stream. More doesn't look better: it drops. If your upload can't carry it, the calculator gives you yours.
Keyframe interval2 s: Twitch asks for it. On 0 (auto) the stream sometimes takes a while to start for people joining.
Twitch Enhanced BroadcastingOptional: New since OBS 30.2: OBS sends several qualities at once and Twitch picks the bitrate for you. Needs Windows and an NVIDIA or AMD card. Turn it on and the calculator above no longer applies.
Profilehigh: Compresses better than main or baseline, and anything from the last ten years plays it.
B-frames2: Frames that lean on the one before and after: more quality for the same kbps. 2 works well live.

Audio

Sample rate48 kHz: The video standard. Set the same in Windows for mic and speakers, or OBS has to convert and sometimes crackles.
ChannelsStereo: What everyone hears. If the mic only plays on one side, tick mono in Advanced Audio Properties.
Audio bitrate160 kbps: Plenty for voice and music. If live music is your thing, go up to 320: those extra kbps barely show in the video.

Video

Base (canvas) resolutionYour screen's: It's the canvas you place things on. Same as your screen and captures fit with no borders.
Output resolutionWhatever the calculator says: What reaches Twitch. With a low bitrate, sharp 720p looks better than blocky 1080p.
Downscale filterLanczos (or bicubic): Scaling 1440p or 1080p down to 720p, Lanczos keeps text sharper. Costs the card a touch more.
FPS60 for fast games, 30 for the rest: 60 frames cost almost double. If you talk or play music, 30 gives cleaner frames.

Mic filters

Right-click the mic in the audio mixer › Filters. Order matters: top to bottom.

Noise suppressionRNNoise
Removes fan, keyboard and street noise. With an NVIDIA RTX card, NVIDIA's is even better.
Noise gateClose −45 dB · Open −35 dB
Mutes the mic while you're not talking. Tweak until it stops clipping the start of sentences.
CompressorRatio 4:1 · Threshold −18 dB
Evens out whispering and shouting so nobody has to touch the volume.
Limiter−1 dB
The ceiling: whatever happens, your voice won't clip. Always last.

Recording at the same time

Recording formatHybrid MP4: People used to record MKV and remux, because a plain MP4 is lost entirely if OBS crashes. The hybrid MP4 in recent versions survives a crash and opens in any editor.
Recording encoderUse stream encoder: That way the card encodes once. If you want a higher-quality recording to edit, use a separate encoder with constant quality (CQP).