Binary to octal converter
1010 in binary is 12 in octal: the converter groups your bits in threes from the right, turns each group into a digit from 0 to 7 and reports the bit count. Handy for homework and Unix permission bits. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Binary
- 1010
- Octal
- 12
- Bits
- 4
- Base
- 8
A binary to octal converter rewrites a string of zeros and ones as a base-eight numeral so every three bits become one compact digit from zero through seven. You type a sequence such as one zero one zero and receive twelve, which is the same integer written with place values that are powers of eight instead of powers of two. Students use the tool to check homework on triplet grouping and place-value charts; developers use it when documenting Unix-style permission bits, instruction encodings, or register dumps that are easier to scan as octal than as long runs of zeros and ones. Only the digits zero and one are accepted: any letter, space inside the number, punctuation, 0b prefix, or other symbol fails with a clear validation error instead of a silent wrong answer.
How binary to octal conversion works
Start with a finite string that uses only the characters zero and one. Whitespace at the ends may be trimmed so a pasted homework line does not fail for a stray newline, but every remaining character must still be a binary digit. If the value is zero, both the cleaned binary and the octal result are the single digit zero and you are done.
For a positive bit pattern, strip redundant leading zeros so the reported bit count reflects the significant bits, then pad on the left with zeros only as needed so the length becomes a multiple of three. Each group of three bits is a triplet because two cubed equals eight: reading left to right, those three places are worth four, two, and one, and their sum is an integer from zero through seven. Map that integer to the octal alphabet zero through seven and concatenate the digits.
The result has no zero-o prefix and no leading zeros except when the entire value is zero.
Where binary to octal tools show up in real work
Secondary-school and introductory computer-science courses teach that three binary digits map to one octal digit; a trusted oracle that returns both the cleaned bit string and the octal value speeds answer keys and classroom demos without spreadsheet formulas.
Unix and POSIX notes often list file-mode bits in octal next to their binary expansions so reviewers can verify read, write, and execute flags at a glance — seven is one one one, six is one one zero, and five is one zero one — which is the same triplet map this converter applies to any bit string, not only nine-bit modes.
Embedded and compiler notes still describe instruction fields and shift counts in octal because historical assemblers grouped bits by threes; turning a binary dump into octal is the check that a listing matches a comment. Coding-interview warm-ups and online judges ask candidates to implement binary-to-octal conversion; tutors compare student output against a known-good string for zero, powers of two, and full-triplet edge cases such as seven and five hundred eleven.
Treat binary-to-hex conversion, decimal-to-octal conversion, text-to-octal encoding of bytes, and general multi-base radix tables as separate search intents with their own landings rather than stretching this bit-string converter past its honest scope.
What you can do with it
Homework and triplet drills
Check textbook answers for grouping bits into threes and mapping each triplet to an octal digit from 0–7, including zero and full-byte patterns such as 11111111 → 377.
Permission bits and instruction dumps
Turn binary flag or mode strings into compact octal when writing Unix file-mode notes, assembler comments, or hardware reference pages that still speak base eight.
FAQ
What inputs does the binary to octal converter accept?
Optional leading and trailing whitespace is trimmed. Any other character — including a 0b prefix, letters, punctuation, or a space inside the bits — is rejected.
How is the octal result formatted?
Digits 0–7 with no 0o prefix and no leading zeros except for the value zero itself (for example 1010 → 12, 11111111 → 377). Conversion groups bits in threes from the right because 2³ = 8.
What happens if I enter a character other than 0 and 1?
Digits 2–9, letters, punctuation, a 0b prefix, and spaces inside the bit string are not accepted, so a mistyped homework sample cannot become a silent wrong octal value.
What does it cost?
The browser tool is free and runs locally.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/conv/binary-to-octal \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"binary":"1010"}'const res = await fetch("https://api.kit.forhosting.com/conv/binary-to-octal", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"binary": "1010"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/binary-to-octal",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"binary": "1010"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/binary-to-octal", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"binary":"1010"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"binary":"1010"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/binary-to-octal", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"binary": "1010"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.binary_to_octal",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_bits | 256 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Pricing for successful API calls is the published base of $0.002 per item.
How binary to octal conversion works
Unlike some programming-language parsers, this converter does not accept a zero-b prefix: the letter b is a character other than zero and one, so a prefixed sample is rejected with invalid_input rather than silently decoded. Equivalently, the same integer can be obtained by evaluating the binary place-value sum and rewriting it in base eight, but triplet grouping is exact integer arithmetic with no floating-point rounding, no random seeds, no wall-clock timestamps, and no network calls, so identical inputs always produce identical JSON. Strings longer than two hundred fifty-six bits are rejected so browser and Worker work stays bounded.
What you send and what you get back
Send a single required field binary holding a string of zeros and ones. Worked examples include binary one zero one zero mapping to octal twelve with four bits, binary one one one one one one one one mapping to octal three seven seven with eight bits, and binary zero mapping to octal zero with one bit. If you need four-bit grouping into hexadecimal, a decimal rewrite of the same bits, or arbitrary source and target bases from two through thirty-six in one call, use those dedicated landings rather than overloading this binary-to-octal page. Aliases bits, value, n, input, and text are accepted so forms and scripts can use the name that fits their UI. binary should be a JSON string; a bare non-negative integer whose decimal digits happen to be only zero and one is coerced, but the documented contract is a digit string so leading zeros are not lost at the JSON layer. Missing binary, empty strings after trim, characters other than zero and one, and strings longer than two hundred fifty-six bits fail with invalid_input and are not charged. On success the response echoes the cleaned binary string under binary, the octal digit string under octal, the significant bit count under bits, and base set to eight for explicitness in multi-tool pipelines. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance.
Where binary to octal tools show up in real work
Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance.
Integration use cases
Interview and unit-test fixtures
Generate expected octal strings for coding exercises and golden tests covering powers of two, all-ones triplets, and edge-length bit strings that must reject a stray 2.
Technical questions
Is there a length limit?
Yes. After trim, the binary string may contain at most 256 bits so conversion stays bounded in the browser and on the Worker. Longer strings fail with invalid_input.