Key takeaways
- Fiber is number one. It is symmetric and steady, with the same speed up as down and maybe a couple milliseconds of jitter.
- Cable is fine, but the provider box is usually the problem. A real router, roughly $150 and up, fixed more cable calls than any speed upgrade.
- 5G home internet is a trap as your primary line. Traders have measured 20 milliseconds one minute and 90 the next from the same box, but it is excellent as a backup.
- Starlink is legitimate when it is your only choice. US median latency is roughly 25 to 40 milliseconds, but your dish hands off about every 15 seconds.
- Jitter matters more than download speed. A 900 megabit line with ugly jitter will hurt you more at the open than a steady 200 megabit line.
I had a futures trader in Ohio call me last year convinced his platform was broken. His fills at the open were clean and his fills at 9 at night were garbage. Same machine, same broker, same charts, same internet plan all day long.
He was handing back about two ticks of slippage on every evening entry. Two ticks on the NQ is $10 a contract, and he was trading five contracts at a time. That's 50 bucks given away on every single night trade, and it went on for months.
His download speed never moved an inch. One other number did, and it's the one his provider never sold to him. That number is called jitter.
What is jitter and why does it matter more than download speed?
Latency is how long a round trip takes from your machine out to the world and back. Jitter is how much that round trip changes from one packet to the next.
If your quotes arrive every 20 milliseconds like clockwork, your ladder and your DOM look smooth and your fills feel honest. If they arrive at 20 milliseconds, then 85, then 25, then 90, your DOM stutters, and you blame your platform for something your internet did to you.
A big download number on a speed test hides all of that. A 900 megabit line with ugly jitter will hurt you more at the open than a boring 200 megabit line that never wavers. So I'm ranking the four connections for trading, not for streaming movies.
One thing first. Before you blame your internet line for anything, find out whether the processor in your computer can keep up with the data pouring into it. I built a free CPU benchmark test for traders. It scores your processor, tells you exactly how it stacks up for trading, and takes about two minutes. Do that first, because a perfect line feeding a slow machine will still give you a stuttering chart.
The 4 internet connections for trading, ranked
| Rank | Connection | Verdict |
|---|---|---|
| 1 | Fiber | The obvious answer: symmetric and steady |
| 2 | Cable | Fine, with a real router and outside the evening rush |
| 3 | 5G home internet | A trap as primary, excellent as backup |
| 4 | Starlink | Legitimate when it's Starlink or nothing |
1. Fiber: the obvious answer
The reason fiber wins has nothing to do with the download number on the brochure. Fiber is symmetric and it's steady. You get the same speed up as you get down, and your orders leave the house on the upload path.
Cable will hand you 1,000 megabits down, no problem, but even on upgraded plans only 100 or 200 up. Fiber usually gives you the same in both directions, with maybe a couple milliseconds of jitter. In 16 years of running this company, I can count on one hand the fiber guys who called us back about the same problem twice.
2. Cable: fine, but traders get the story backwards
Most of the cable cases we've worked over the last year had nothing to do with the plan the trader was paying for. It was the box the provider dropped off, sitting there running its own Wi-Fi and its own extra set of software features while the trader pushed every order through it.
Putting a real router in front of that box fixed more of those calls than any speed upgrade from the provider ever did. By a real router, I mean a standalone unit from an actual networking brand, roughly $150 and up, with the provider box set to pass through and your machine on an Ethernet cable. If you're still on wireless, read wired vs. wireless internet for trading.
Here's the tell I listen for on the phone. If your charts keep painting fine but the order confirmation hangs a beat behind the click, that's your upload path. Download is doing its job and upload is not, and your download number won't show you that.
The other soft spot with cable is that your whole neighborhood shares the same line. Think about a school hallway. During class it's empty and you can walk end to end in 10 seconds. The second the bell rings, everybody pours out at once and that same walk takes two minutes of bumping shoulders.
Early in the morning, most of your neighbors are at work, so your orders walk down an empty hallway. Around eight or nine at night, everybody's home streaming movies, gaming and scrolling on their phones. That's when the bell rings on your street.
That was my trader in Ohio. He liked trading NQ in the evening session, which lined up perfectly with the busiest hour in his neighborhood. His jitter went from 6 milliseconds in the morning to 70 at night. He moved his primary line to fiber, kept the cable as backup, and the stuttering completely stopped.
3. 5G home internet: a trap as your primary line
I've had traders measure 20 milliseconds one minute and 90 the next from the same box sitting in the same window. You're just a guest on a tower built for cell phones, and the load on that tower and the weather are not yours to control.
As a backup line, 5G is genuinely excellent. Buy a dual WAN router. Put fiber or cable on the primary port and the 5G box on the second. Set the failover trigger on latency and packet loss, not just on the line going dead. A cable line that's technically alive and spewing 200 milliseconds won't trip a link-down rule, and that is exactly the morning you need the switch to happen. I go further into this in the backup plan for when your internet dies.
4. Starlink: legitimate when it's your only choice
Let me be fair about it. Median latency in the US has come down into the roughly 25 to 40 millisecond range, and in plenty of rural markets it beats the local cable company outright.
But you don't get filled on medians. Those satellites move so fast overhead that your dish hands you off about every 15 seconds, and heavy rain and a tree branch in the wrong spot are still real. If fiber or cable reaches your address, that needs to be your primary. If your only choice is Starlink or nothing, Starlink is a legitimate way to day trade today. Rural traders should also read what your ping costs you per fill.
How much latency and jitter can each trading style handle?
| How you trade | Latency | Jitter | Packet loss |
|---|---|---|---|
| Swing trading | Under 100 ms | Stop thinking about it | None |
| Day trading stocks or options | Under 50 ms average | Under 10 ms | Zero |
| Scalping futures | Under 30 ms | Under 5 ms if possible | None at all |
Remember the point of all this: a rock-solid 28 will treat you better than a spiky 12.
How to test your internet line for latency and packet loss
- Open the Run box. Hold down the Windows key and press R.
- Open the command window. Type cmd and press Enter.
- Start the ping test. In the black window, type ping -n 100 1.1.1.1 and press Enter.
- Let it run and read the bottom. Give it about 100 seconds. When it finishes, look for the minimum, maximum and average round trip times, and the line above them that says lost.
- Check for packet loss. On a wired connection, any loss above zero is worth a call to your provider.
- Work out your spread. Subtract the minimum from the maximum. One ugly spike can inflate it, so treat a big spread as a reason to dig deeper, not as your jitter figure.
- Repeat at the right times on Ethernet. Run it on Ethernet, never on Wi-Fi, once at 9:25 before the market opens and once at 9 at night.
- Ping your broker's gateway. Run the exact same command against the server address your platform connects to when you log in, which you can find on your broker's support pages.
Is the problem your line, your broker or your computer?
If you trade with Interactive Brokers, their ndc1 server is the example I use. For other brokers, look up their data feed and server addresses in their support pages and swap yours in.
One heads up. Some broker servers are set to ignore ping completely, so every line comes back as timed out. That doesn't mean your connection is dead. It just means that server won't answer, so try another address from your broker's list.
If 1.1.1.1 comes back clean and the broker path looks ugly, the problem is upstream of you. That's a support ticket, not a hardware purchase. For more ways to sort this out, see how to tell if it's your internet or your trading computer.
What to do if you find an ugly number
That's bigger than one command. I put together a free Complete Guide to Trading Computers that walks you through your internet line, your router, your machine, and what each one does to your fills.
There's another reason to get it. I've been trading electronically since the mid-1990s, and most traders who call us certain their internet is broken have a clean line. The problem is their machine can't keep up. So run the free two-minute benchmark test, grab the guide, and if you want to see what we have right now, here are our desktop trading computers.
Frequently Asked Questions
What internet speed do I need for trading?
The download number is the wrong thing to chase. A 900 megabit line with ugly jitter will hurt you more at the open than a steady 200 megabit line. What matters is latency, jitter and packet loss. Swing traders should stay under 100 milliseconds with no loss. Day traders in stocks or options should aim for under 50 milliseconds average, jitter under 10 and zero loss. Futures scalpers want under 30, jitter under 5 if possible, and no loss at all.
What is the best broadband for trading and low-latency applications?
Fiber. It's symmetric, so you get the same speed up as down, and your orders leave the house on the upload path. It's also steady, usually with a couple milliseconds of jitter. Cable often gives 1,000 megabits down but only 100 or 200 up, even on upgraded plans. In 16 years of running EZ Trading Computers, I can count on one hand the fiber traders who called back about the same problem twice.
How do I set up automatic failover to mobile broadband if my main line goes down?
Buy a dual WAN router. Put your fiber or cable on the primary port and your 5G home internet box on the second. Set the failover trigger on latency and packet loss, not just on the line going dead. A cable line that's technically alive but spewing 200 milliseconds won't trip a link-down rule, and that's exactly the morning you need the switch to happen.
Can you day trade on Starlink?
Yes, if it's your only choice. US median latency has come down into the roughly 25 to 40 millisecond range, and in plenty of rural markets it beats the local cable company. But you don't get filled on medians. The dish hands off about every 15 seconds, and heavy rain or a tree branch in the wrong spot still cause trouble. If fiber or cable reaches your address, make that your primary line.
Why are my fills worse in the evening than at the open?
On cable, your whole neighborhood shares the same line. Early in the morning most neighbors are at work, but around eight or nine at night everyone is home streaming, gaming and scrolling. One trader I worked with saw his jitter go from 6 milliseconds in the morning to 70 at night, costing him about two ticks per evening entry. Moving his primary line to fiber stopped it.
Why do my charts look fine but my order confirmations lag?
That's the tell I listen for on the phone. If your charts keep painting fine but the order confirmation hangs a beat behind the click, your upload path is the problem. Download is doing its job and upload is not, and your download number won't show you that. On cable, the provider's box is often the culprit, and a standalone router in front of it, with the box in pass-through, fixes many of these cases.
