Urine output calculator
Collecting 840 mL of urine over 12 hours from a 70 kg patient is exactly 1 mL per kilogram per hour, within the adequate teaching band. Enter volume, weight and hours to compare collections fairly across body sizes. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Urine volume
- 840
- Weight
- 70
- Hours
- 12
- Urine output ml per kg per h
- 1 mL/kg/h
- Urine output ml per h
- 70
- Urine output ml per kg
- 12
- Daily equivalent ml
- 1,680
Urine output rate in milliliters per kilogram per hour is how nursing, physiology, and chart-practice courses compare a measured collection with body size and elapsed time. This urine output calculator accepts collected urine volume in milliliters, patient weight in kilograms, and collection hours, then returns the rate as volume divided by the product of weight and hours.
What urine output rate means and how milliliters per kilogram per hour are computed
Urine output rate answers a three-part question: how many milliliters of urine were collected, over how many hours, and for a person of what body mass. The closed form is urine volume in milliliters divided by the product of weight in kilograms and collection hours, which yields milliliters per kilogram per hour. That normalization lets a six-hour bag from a seventy kilogram adult be compared with a twelve-hour bag from a smaller patient without mixing raw milliliters that are not on the same scale.
A classic teaching check is eight hundred forty milliliters over twelve hours in a seventy kilogram patient, which is exactly one milliliter per kilogram per hour because eight hundred forty divided by eight hundred forty is one. Two hundred forty milliliters over eight hours in an eighty kilogram patient is zero point three seven five milliliters per kilogram per hour, which sits in the oliguria teaching band used in many adult nursing texts. Zero collected volume is a valid measurement and yields a rate of zero.
Zero weight or zero hours cannot define the quotient, so they fail instead of returning Infinity.
Where a urine output calculator earns its keep
Nursing and physiology courses constantly assign milliliters-per-kilogram-per-hour drills from textbook intake-and-output panels, so a single trusted oracle that returns the rate, the hourly and per-kilogram companions, the twenty-four-hour equivalent, and a transparent teaching band speeds grading and demo setup. Chart-practice labs use the same arithmetic as a bedside worksheet check before discussing oliguria thresholds, fluid balance, or why a raw milliliter total is not comparable across body sizes.
Product teams building educational simulation widgets want a documented volume-weight-hours path that clients can audit by hand rather than a black-box kidney engine that mixes several scores without disclosure. Research assistants preparing synthetic intake-and-output datasets need stable rate labels from known triples without network calls or model drift.
If you later need fractional excretion of urea, sweat rate from weight change, or a neonatal SNAP score that merely includes urine as one of several items, treat those as separate search intents and landings rather than overloading this urine output calculator page. Always present results as educational estimates of a measured rate; clinical decisions require qualified professionals, local protocols, and assays this tool does not collect.
What you can do with it
Classroom intake-and-output answer keys
Generate milliliters per kilogram per hour, companion quotients, and a teaching band from textbook volume, weight, and hours so instructors and auto-graders share one transparent ground truth.
Nursing and physiology demos
Show why a raw milliliter total is not comparable across body sizes without mixing diagnostic scores or pediatric cutoffs on the same landing.
FAQ
How is urine output rate calculated?
Divide collected urine volume in milliliters by the product of body mass in kilograms and collection hours. The primary result is milliliters per kilogram per hour (mL/kg/h).
What happens if hours or weight is zero?
A zero collection interval or a zero body mass cannot define milliliters per kilogram per hour, so the engine rejects it rather than returning Infinity.
How do I format the input?
Volume may be zero; weight and hours must be strictly greater than zero.
What does the urine output calculator cost?
The browser tool is free and runs locally.
What do the urine output teaching bands mean?
Below 0.3 mL/kg/h is labelled anuria, below 0.5 oliguria, 0.5 to 2 adequate and above 2 high. These are classroom conventions, not a diagnosis and not KDIGO staging.
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/health/urine-output \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"urine_volume":840,"weight":70,"hours":12}'const res = await fetch("https://api.kit.forhosting.com/health/urine-output", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"urine_volume": 840,
"weight": 70,
"hours": 12
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/health/urine-output",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"urine_volume": 840,
"weight": 70,
"hours": 12
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/urine-output", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"urine_volume":840,"weight":70,"hours":12}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"urine_volume":840,"weight":70,"hours":12}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/urine-output", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"urine_volume": 840,
"weight": 70,
"hours": 12
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "health.urine_output",
"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_urine_volume_ml | 100000 |
max_weight_kg | 500 |
max_hours | 168 |
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
A zero body mass or a zero collection interval cannot define a per-kilogram-per-hour figure, so those cases fail with invalid_input instead of Infinity. Successful API calls are billed at $0.002 per item; validation failures are not charged.
What urine output rate means and how milliliters per kilogram per hour are computed
The engine also reports milliliters per hour, milliliters per kilogram, and a twenty-four-hour equivalent obtained by scaling the same rate, plus an educational teaching_band that labels anuria below zero point three, oliguria below zero point five, adequate from zero point five through two, and high above two milliliters per kilogram per hour. Those bands are classroom conventions, not a diagnosis, not KDIGO staging, and not a substitute for pediatric cutoffs that often use one milliliter per kilogram per hour. The arithmetic is pure floating-point with no network, no random seed, and no wall-clock time, so identical triples always produce identical JSON after stable rounding.
Input contract, response shape, and error behaviour
Zero weight fails because a zero body mass cannot define milliliters per kilogram. Zero hours fails because a zero interval cannot define a rate per hour. Negative volume, negative weight, and negative hours are rejected the same way. POST a JSON body with three required finite numbers. The field urine_volume is the collected volume in milliliters and must be zero or greater, up to one hundred thousand milliliters; aliases volume, volume_ml, urine_ml, output, and urine are accepted. The field weight is body mass in kilograms and must be strictly greater than zero and at most five hundred kilograms; aliases weight_kg, mass, and body_weight are accepted. The field hours is the collection interval and must be strictly greater than zero and at most one hundred sixty-eight hours; aliases duration, duration_hours, collection_hours, and time_hours are accepted. Missing fields, empty strings, non-numeric tokens, NaN, and Infinity fail with invalid_input naming the field and are not billed. On success the body echoes the cleaned urine_volume, weight, and hours; returns urine_output_ml_per_kg_per_h as the primary rate; returns urine_output_ml_per_h and urine_output_ml_per_kg as companion quotients; returns daily_equivalent_ml as the same rate scaled to twenty-four hours; labels teaching_band with the adult educational band; sets unit to mL/kg/h; and restates formula as urine_output equals urine_volume divided by weight times hours with method ml_per_kg_per_hour.
Where a urine output calculator earns its keep
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
Deterministic I-and-O fixtures
Bulk-produce stable urine-output-rate labels for synthetic panels and regression tests with hard invalid_input on zero weight or zero hours.
Technical questions
What does teaching_band mean?
It is an adult educational label: anuria below 0.3 mL/kg/h, oliguria below 0.5, adequate from 0.5 through 2, and high above 2. It is not a diagnosis and does not apply pediatric cutoffs.