Round to decimal places
Round 3.14159 to two decimal places and you get 3.14; to four, 3.1416. Choose from zero to fifteen places and see the number before and after, rounded half away from zero as taught in school. Free in your browser.
- Free
- Runs in your browser
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- Your data stays on your device
Run — free
Worked example
- Value
- 3.14159
- Places
- 2
- Before
- 3.14159
- After
- 3.14
- Rounded
- 3.14
Rounding to a fixed number of decimal places is one of the first precision skills taught in school mathematics, science labs, and everyday money work. Students, tutors, and app builders need a clear answer that shows both the original figure and the rounded result, not a black-box output that hides what changed. This round-to-decimal-places calculator accepts any finite number and an integer places count from zero through fifteen, applies standard half-away-from-zero rounding, and returns the value before and after so you can teach, check homework, or wire a form field with a deterministic contract.
What rounding to decimal places means
When you round a number to N decimal places you keep N digits after the decimal point and decide whether the last kept digit stays or goes up by one. The decision depends on the next digit and on the rounding rule in force.
Standard school and commercial practice for this tool is half away from zero: if the first discarded digit is five or greater, the magnitude of the kept part increases by one unit in the last place; if it is four or less, the kept digits stay as they are. For a positive example, 3.14159 rounded to two decimal places becomes 3.14 because the third decimal is one, which is less than five. The same number rounded to four places becomes 3.1416 because the fifth digit is nine.
For a negative example, negative 2.5 rounded to zero decimal places becomes negative 3, because half cases move away from zero rather than toward it. Zero places means the nearest integer.
Where a decimal-places rounder earns its keep
Classrooms use a round-to-decimal-places calculator so students can check money, measurement, and science answers without hand errors on the half digit. Homework portals and LMS plugins need a deterministic oracle that marks 2.5 to zero places as 3 (or negative 3 for negative input) under a published rule instead of depending on a browser Math.round quirk that differs by language. Failed validation does not consume balance.
Keep requests small, pin before and after in tests, and you get reproducible rounding for teaching, grading, and edge workers without standing up a full computer-algebra stack.
What you can do with it
Classroom and homework checks
Let students enter a number and a places count, then compare the before and after fields against textbook half-up examples.
LMS and auto-grading
Mark decimal-places items with a deterministic oracle that applies half-away-from-zero and never silently changes rule mid-term.
Forms and display snap
Snap money or measurement inputs to two or four decimals before storage while logging the original value for audit.
FAQ
How do I round a number to decimal places?
Send a finite value and an integer places from 0 to 15.
What rounding rule is used?
Standard half away from zero: when the first discarded digit is 5 or greater, magnitude increases by one in the last kept place. Ties do not bank to even.
What does places equal to zero mean?
Zero decimal places means round to the nearest integer. For example 2.5 becomes 3 and −2.5 becomes −3.
How do negative numbers round?
They round away from zero on a half, just like positive ones. Negative 2.5 to zero places becomes negative 3, and negative 1.235 to two places becomes negative 1.24, because the dropped digit is a five.
How many decimal places can I keep?
Any whole number of places from zero to fifteen. A request such as 2.5 places, or anything above fifteen, is refused with a clear message instead of being guessed.
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/edu/round-to-places \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"value":3.14159,"places":2}'const res = await fetch("https://api.kit.forhosting.com/edu/round-to-places", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"value": 3.14159,
"places": 2
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/edu/round-to-places",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"value": 3.14159,
"places": 2
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/edu/round-to-places", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"value":3.14159,"places":2}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"value":3.14159,"places":2}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/edu/round-to-places", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"value": 3.14159,
"places": 2
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "edu.round_to_places",
"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.
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
The same pure logic runs free in the browser and on the paid API path, so classroom demos and production pipelines never disagree on a half-up edge case.
What rounding to decimal places means
Fifteen places is the practical upper bound for stable floating-point display in this API. The endpoint always echoes the cleaned original as before and the rounded result as after (and as rounded), so a learner can read the transformation in one response without retyping the input.
Input contract, response shape, and error behaviour
Places may also be sent as decimals, precision, or dp. Places outside zero through fifteen, or non-integer places such as 2.5, likewise fail with a clear message. Example: value 3.14159 and places 2 yields before 3.14159 and after 3.14. Example: value negative 1.235 and places 2 yields after negative 1.24 because the third decimal is five and the rule moves away from zero. POST a JSON body with two required fields: value, the finite number to round, and places, an integer from zero to fifteen inclusive. Value may arrive as a JSON number or as a numeric string such as "3.14159"; aliases n, number, input, x, and num are accepted when value is omitted. Missing fields, empty strings, non-numeric text, NaN, and Infinity fail with invalid_input and are not billed. On success the body includes value and before (the original after float cleanup), places, after and rounded (the same rounded number under two names for display and for API clients that expect a single result field), method set to half_away_from_zero, a short formula string, and a human-readable message that states the before and after figures. Pair the response with your own UI labels; this endpoint does not emit charts or multi-step prose beyond the message and formula fields.
Where a decimal-places rounder earns its keep
Spreadsheet migrations and form validators often need to snap display values to two or four decimals before storage; calling a tiny parse API avoids reimplementing edge cases in every stack.
Technical questions
What input is rejected?
Missing value or places, non-numeric text, NaN, Infinity, and places outside 0–15 fail with invalid_input and are not billed.
What does the round to decimal places tool cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.