Web Serial Terminal

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serial terminal 115200 baud 8n1

Serial terminal 115200 baud 8N1: parameters and speed

Choose 115200 in the baud list and, if you need another format, open Port options to change data bits, parity, stop bits and flow control. The chosen format shows beside the baud rate, with the ceiling in bytes per second.

Baud, frame and bytes per second

Baud is the number of symbols per second, and on a simple serial line each symbol is one bit. But a useful byte does not travel alone: each frame carries 1 start bit, the data bits, 1 parity bit if any and 1 or 2 stop bits. In 8N1 that is 1 + 8 + 0 + 1 = 10 bits per byte, so 115200 baud carries at most 11,520 bytes per second, and 9600 baud carries 960.
The Web Serial API parameters are these: required baud rate, 7 or 8 data bits (default 8), 1 or 2 stop bits (default 1), parity none, even or odd (default none) and flow control none or hardware (default none). A 7E2 format uses 1 + 7 + 1 + 2 = 11 bits per byte, and at 9600 baud that gives about 873 bytes per second. Parity serves to detect a flipped bit on the wire, and hardware flow control uses the RTS and CTS lines so the receiver can ask for a pause.
Both sides must use exactly the same baud rate and format, because there is no shared clock: each side times the bits on its own. Any difference produces swapped characters or framing errors. The terminal uses a 64 KB read buffer, larger than the API default of 255 bytes, to avoid losing data at high speeds, and it resumes reading after non-fatal errors such as parity or framing errors.

Formats and data ceiling

115200 8N1

Input: 115200 baud, 8N1
Expected output: 11.520 bytes/s

10 bits per byte.

9600 8N1

Input: 9600 baud, 8N1
Expected output: 960 bytes/s

1 KB takes about 1.07 s.

921600 8N1

Input: 921600 baud, 8N1
Expected output: 92.160 bytes/s

Eight times 115200.

9600 7E2

Input: 9600 baud, 7E2
Expected output: 873 bytes/s

11 bits per byte.

One kilobyte at 115200 8N1

Input: 1.024 bytes
Expected output: 88,9 ms

1,024 / 11,520 s.

Full tool FAQ

What is Web Serial and which browsers have it?

It is an API that lets a page access serial ports with your permission. Per caniuse on 2026-11-02, it works in Chrome and Edge 89 or newer, Opera 76 or newer, Firefox on desktop from version 151 and Chrome for Android from 156. It does not work in Safari, on iPhone, in Firefox for Android or in Samsung Internet.

How do I connect an Arduino or an ESP board?

Which baud rate should I use?

What does 8N1 mean?

Why does it not work on iPhone, Safari or older Firefox?

Which line ending should I choose when sending?

How do I send bytes in hexadecimal?

Does the log grow without limit?

What if I pull the cable mid-session?

Is it safe? Does my data go to a server?

Frequently asked questions

Can I use a baud rate that is not on the list?

Yes. Choose Other value and type a positive whole number. The board or converter hardware must support it, and a value the converter cannot reach exactly may cause framing errors.

What is the difference between baud and bits per second?

On a simple serial line, with one bit per symbol, they are equal. What changes is the useful rate: part of the bits is framing. In 8N1, 20% of the bits (start and stop) carry no data.

Why do I get strange characters?

The most common cause is a baud rate different from the device's. Next come a different format (bits, parity or stop) and a missing common ground between the two sides. Check the baud rate first.

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serial terminal 115200 baud 8n1

Serial terminal 115200 baud 8N1: parameters and speed

Baud, frame and bytes per second

Baud is the number of symbols per second, and on a simple serial line each symbol is one bit. But a useful byte does not travel alone: each frame carries 1 start bit, the data bits, 1 parity bit if any and 1 or 2 stop bits. In 8N1 that is 1 + 8 + 0 + 1 = 10 bits per byte, so 115200 baud carries at most 11,520 bytes per second, and 9600 baud carries 960.

The Web Serial API parameters are these: required baud rate, 7 or 8 data bits (default 8), 1 or 2 stop bits (default 1), parity none, even or odd (default none) and flow control none or hardware (default none). A 7E2 format uses 1 + 7 + 1 + 2 = 11 bits per byte, and at 9600 baud that gives about 873 bytes per second. Parity serves to detect a flipped bit on the wire, and hardware flow control uses the RTS and CTS lines so the receiver can ask for a pause.

Both sides must use exactly the same baud rate and format, because there is no shared clock: each side times the bits on its own. Any difference produces swapped characters or framing errors. The terminal uses a 64 KB read buffer, larger than the API default of 255 bytes, to avoid losing data at high speeds, and it resumes reading after non-fatal errors such as parity or framing errors.

Formats and data ceiling

115200 8N1

Input: 115200 baud, 8N1
Expected output: 11.520 bytes/s

10 bits per byte.

9600 8N1

Input: 9600 baud, 8N1
Expected output: 960 bytes/s

1 KB takes about 1.07 s.

921600 8N1

Input: 921600 baud, 8N1
Expected output: 92.160 bytes/s

Eight times 115200.

9600 7E2

Input: 9600 baud, 7E2
Expected output: 873 bytes/s

11 bits per byte.

One kilobyte at 115200 8N1

Input: 1.024 bytes
Expected output: 88,9 ms

1,024 / 11,520 s.

Full tool FAQ

What is Web Serial and which browsers have it?

How do I connect an Arduino or an ESP board?

Which baud rate should I use?

What does 8N1 mean?

Why does it not work on iPhone, Safari or older Firefox?

Which line ending should I choose when sending?

How do I send bytes in hexadecimal?

Does the log grow without limit?

What if I pull the cable mid-session?

Is it safe? Does my data go to a server?

Frequently asked questions

Can I use a baud rate that is not on the list?

Yes. Choose Other value and type a positive whole number. The board or converter hardware must support it, and a value the converter cannot reach exactly may cause framing errors.

What is the difference between baud and bits per second?

On a simple serial line, with one bit per symbol, they are equal. What changes is the useful rate: part of the bits is framing. In 8N1, 20% of the bits (start and stop) carry no data.

Why do I get strange characters?

The most common cause is a baud rate different from the device's. Next come a different format (bits, parity or stop) and a missing common ground between the two sides. Check the baud rate first.