Find the right number first
A speed test shows two numbers. Download is what comes into the building. Upload is what leaves it, and a live stream is all about what leaves. Home and office lines often have far less upload than download, so a line sold as fast can still be tight for this.
Check the unit too. Streaming uses Mbps (megabits per second). Some apps show MB/s (megabytes), and one megabyte is eight megabits, so 1 MB/s is 8 Mbps.
Here's the good news. You send one copy of your picture, however many people watch. Your video channel makes the copies for your viewers, so 10 viewers or 1,000 take the same upload from you. Sending on to YouTube or Facebook through Stream Targets in your dashboard takes no extra upload from you either, because your channel does that sending.
Measure it the honest way
- Go to the actual spot. Not the office down the corridor: the place where the laptop will sit.
- Pick the same hour on the same kind of day. A church is quiet on Wednesday and full of phones on Sunday at 10.
- Use the device you'll stream from, connected the way it will be connected.
- Turn off any VPN. OBS's own troubleshooting guide lists a VPN as a cause of unstable streams.
- Run a speed test three times, a few minutes apart, and write down each upload result.
- Keep the lowest one. Ignore the others, however nice they look.
Do the sum and pick your picture
Halve your lowest result. That's your budget for video and sound together. Sound takes about 0.13 Mbps at the usual 128 kbps, so the rest goes to your video bitrate (how much data you send each second for the picture).
Say a school hall gives you 11.4, 7.9 and 6.2 Mbps. You keep 6.2 and halve it to 3.1. Take off the sound and you've got just under 3 Mbps for video, which means 720p at around 2,900 kbps.
| Lowest upload you measured | A good place to start | Video bitrate |
|---|---|---|
| 10 Mbps or more | 1080p at 30 frames a second | Up to 4,500 kbps |
| 6 to 10 Mbps | 720p at 30 frames a second | About 2,800 kbps |
| 4 to 6 Mbps | 960 x 540 at 30 frames a second | About 1,800 kbps |
| 2.5 to 4 Mbps | 768 x 432 at 30 frames a second | About 1,100 kbps |
| Under 2.5 Mbps | Find a better line | Too tight to rely on |
The top two rows follow the settings in our OBS guide, which suggests 2,500 to 4,500 kbps. The lower rows are our own suggestion, based on sizes in Apple's streaming guidelines. Pro and Platinum channels take up to 5 Mbps at 1080p, so more upload than the top row won't buy you a sharper picture here. Sending straight to YouTube is a different case: its own table asks for more.
Keep the headroom, even when it hurts
It's tempting to use everything the test showed. Please don't. A speed test is a short burst, and your stream has to hold for an hour while someone's phone backs up its photos. If your line can't keep up, OBS has to throw away frames, and if it drops too many, you can be cut off altogether.
OBS's own guide offers 75% of your upload as a starting point. Ours is stricter because you're usually on a shared line you don't control, on a day you can't repeat. If you have a cable into your own router and nobody else on it, 75% is fair.
Turn things down in this order
If the numbers fall short, or the square at the bottom of OBS goes yellow or red, work down this list. The early steps cost you nothing.
- Get other things off the line: phones, cloud backups, updates, a second laptop.
- Swap Wi-Fi for a cable. A long network cable costs little and often makes the biggest difference. OBS names Wi-Fi as a cause of unstable streams.
- Lower the video bitrate, under Settings, then Output. This is the setting that actually cuts your upload. Use the table above for your new figure.
- If the picture turns blocky at the lower bitrate, drop to 720p or 30 frames a second under Settings, then Video, so the same bitrate has less to carry. Changing either one alone won't lower your upload.
- Leave the sound alone. 128 kbps is a sliver of your budget, and people will stay with a soft picture long after they've given up on bad sound.
Sort out shared church or school Wi-Fi
A speed test won't show you these. Most are solved by one friendly chat with whoever looks after the network.
- Ask for a cable to the router. Even a spare socket in the office beats the hall's Wi-Fi.
- Stay off the guest network. Guest Wi-Fi often has its own limits. Ask if there's a staff network you can use for the stream.
- Watch for a sign-in page. If the network asks you to accept terms in a browser, it may ask again halfway through. Ask for your laptop to be let through.
- Ask about blocked connections. School filters may stop your encoder (the app that sends your picture to the internet) from reaching your channel. If it connects from home with the same settings but not here, while web pages still load, this is the likely reason.
A phone hotspot is a fair backup. Test it in the same spot, because thick church walls can eat the signal. Check your data allowance as well: 3 Mbps for an hour uses about 1.35 GB.
Run one real stream before the day
Only a real stream gives you an answer. Send a rehearsal for 20 minutes, at the hour you'll go live, with your real settings. The Free plan is meant for testing your encoder and player. The 1080p, 5 Mbps limit is published for Pro and Platinum, so if you'll go live at 1080p, rehearse on the plan you'll use.
- Start streaming and watch the square at the bottom of OBS. Green is healthy.
- On your channel's Overview, check that the bitrate coming in holds steady near what you set.
- Open your player on a phone using mobile data, and watch for a few minutes. Your picture will usually be 10 to 20 seconds behind real time. That's normal.
If something looks wrong and you can't see why, ask. Help is there day and night from our support page, and it's a normal thing to get stuck on the first time.