SNAP-II neonatal score
Add up the six SNAP-II items from a newborn's worst values in the first 12 hours after admission: mean pressure 25, temperature 35.2 °C, ratio 1.5, pH 7.15 and urine 0.5 mL/kg/h give 34 points out of 115. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Mean bp
- 25
- Creativity
- 35.2
- Pao2 fio2
- 1.5
- Ph
- 7.15
- Urine output
- 0.5
- Score
- 34
- Score max
- 115
- Window hours
- 12
- Score name
- SNAP-II
SNAP-II, the Score for Neonatal Acute Physiology II, summarises how ill a newborn is from the worst values recorded during the first twelve hours after admission. This calculator applies the six published 2001 items: lowest mean blood pressure, lowest temperature, lowest PaO2/FiO2 ratio, lowest serum pH, whether multiple seizures occurred, and urine output in millilitres per kilogram per hour. It returns the integer SNAP-II total from zero to one hundred and fifteen, plus a per-item point breakdown you can pin in tests.
What SNAP-II measures and which first-12-hour values you need
SNAP-II is a six-item physiology score for newborns published by Richardson, Corcoran, Escobar, and Lee in 2001 as a shorter successor to the original Score for Neonatal Acute Physiology. It was designed so a neonatal intensive-care team could summarise illness severity from routine first-twelve-hour observations without collecting the much longer original battery. Send the worst values in the first twelve hours for six fields.
Lowest mean blood pressure is arterial mean pressure in millimetres of mercury. Lowest temperature is degrees Celsius, not Fahrenheit; a Fahrenheit nursery reading will sit outside the Celsius bound and fail rather than be converted in silence. The oxygenation item is the SNAP-II PaO2/FiO2 ratio, which is arterial oxygen tension in millimetres of mercury divided by inspired oxygen expressed as a percent from twenty-one to one hundred.
That is why the published cut-offs sit near 2.49 rather than the adult ARDS millimetre-of-mercury scale near two hundred: sixty millimetres of mercury on forty percent oxygen is 60 divided by 40, which equals 1.5. Lowest serum pH is the worst arterial or capillary pH in the window. Urine output is millilitres per kilogram per hour averaged over those twelve hours, including anuria at zero.
Identical inputs always yield the same integer score because the path is pure comparison with no network, no model, no random seed, and no wall clock.
How points are assigned, how to read the score, and when input is rejected
Each item contributes a published integer; the SNAP-II total is their sum, from zero in a physiologically unremarkable first twelve hours to a maximum of one hundred and fifteen. Mean blood pressure at or above thirty millimetres of mercury scores zero, twenty through twenty-nine scores nine, and below twenty scores nineteen. Temperature strictly above 35.6 Celsius scores zero, 35.0 through 35.6 inclusive scores eight, and below 35.0 scores fifteen.
PaO2/FiO2 strictly above 2.49 scores zero, 1.0 through 2.49 scores five, 0.3 through 0.99 scores sixteen, and below 0.3 scores twenty-eight. Serum pH at or above 7.20 scores zero, 7.10 through 7.19 scores seven, and below 7.10 scores sixteen. Multiple seizures add nineteen points when true and zero when false.
Urine output at or above 1.0 millilitres per kilogram per hour scores zero, 0.1 through 0.9 scores five, and below 0.1 including anuria scores eighteen. Use score for a single chip, breakdown for an audit trail, and formula for a teaching caption. Do not treat a high total as a diagnosis, a reason to withdraw care, or a substitute for SNAPPE-II, CRIB-II, or a clinician.
Practical bounds keep classroom numbers sane: mean blood pressure zero to one hundred fifty, temperature twenty-five to forty-three Celsius, PaO2/FiO2 zero to twenty on the SNAP-II scale, pH 6.4 to 7.8, urine output zero to thirty.
What you can do with it
NICU simulation labs and chart-review teaching
Manikin and e-learning cases need a deterministic SNAP-II oracle so the same first-12-hour physiology always yields the same integer illness-severity total.
FAQ
How is the SNAP-II score calculated?
SNAP-II adds published points from six worst first-12-hour items: mean blood pressure, temperature, PaO2/FiO2, serum pH, multiple seizures, and urine output (mL/kg/h). The integer total runs from 0 to 115.
What PaO2/FiO2 ratio does SNAP-II use?
Send PaO2 in mmHg divided by FiO2 as a percent (21–100), not the adult ARDS mmHg scale. Example: PaO2 60 mmHg on 40% oxygen is 60/40 = 1.5, which scores 5 points.
What happens if urine output is negative?
A flow rate in mL/kg/h cannot be below zero, and that failure is not billed.
Does this calculator include SNAPPE-II or estimate mortality?
No. It returns the six-item SNAP-II physiology score only. It does not add birth weight, Apgar, or small-for-gestational-age points, and it does not output a mortality percentage.
Is this a diagnosis, and what does the SNAP-II calculator cost?
No. It is an educational physiology score, not a medical device. The browser tool runs free on your device.
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/snap-score \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"mean_bp":25,"temperature":35.2,"pao2_fio2":1.5,"ph":7.15,"seizures":false,"urine_output":0.5}'const res = await fetch("https://api.kit.forhosting.com/health/snap-score", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"mean_bp": 25,
"temperature": 35.2,
"pao2_fio2": 1.5,
"ph": 7.15,
"seizures": false,
"urine_output": 0.5
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/health/snap-score",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"mean_bp": 25,
"temperature": 35.2,
"pao2_fio2": 1.5,
"ph": 7.15,
"seizures": false,
"urine_output": 0.5
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/snap-score", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"mean_bp":25,"temperature":35.2,"pao2_fio2":1.5,"ph":7.15,"seizures":false,"urine_output":0.5}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"mean_bp":25,"temperature":35.2,"pao2_fio2":1.5,"ph":7.15,"seizures":false,"urine_output":0.5}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/snap-score", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"mean_bp": 25,
"temperature": 35.2,
"pao2_fio2": 1.5,
"ph": 7.15,
"seizures": false,
"urine_output": 0.5
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "health.snap_score",
"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
Negative urine output is rejected as invalid_input because a flow rate cannot be negative. Successful API items cost $0.002. This is an educational physiology score, not a diagnosis and not a substitute for a neonatologist.
What SNAP-II measures and which first-12-hour values you need
This endpoint implements that table only: it does not add SNAPPE-II birth-weight, Apgar, or small-for-gestational-age points, and it does not convert the total into a mortality percentage. Multiple seizures is a boolean: true only when more than one clinically recognised seizure occurred; a single isolated event scores zero. Missing fields, booleans in numeric slots, empty strings, infinities, and non-numeric text fail with invalid_input naming the field.
How points are assigned, how to read the score, and when input is rejected
Negative urine output is not a band: the request fails with invalid_input stating that urine_output cannot be negative, and that failure is not billed. On success the body echoes the six parsed inputs with stable rounding, lists per-item points in breakdown, and returns score as the integer total, score_max of 115, window_hours of 12, method snap_ii, score_name SNAP-II, and a formula string restating the 2001 table.
API usage, pricing, product workflows, and educational limits
Call the free in-browser SNAP-II calculator for neonatal nursing homework, simulation labs, and chart-review teaching without reimplementing the 2001 bands in every spreadsheet. Store score and breakdown alongside the raw first-twelve-hour vitals for dashboards, and export columns for the six inputs, each point band, and the total. Prefer consistent units: millimetres of mercury, Celsius, SNAP-II PaO2/FiO2 as millimetres of mercury over percent oxygen, pH units, and millilitres per kilogram per hour. Authors shipping SDKs can map score into a badge and breakdown into a six-row checklist that quotes the formula string. Keep expectations educational: a hypotensive, hypothermic, acidotic newborn with oliguria and seizures needs a neonatologist, not an automated label alone. Send a JSON body with required mean_bp, temperature, pao2_fio2, ph, seizures, and urine_output. Aliases such as mbp, temp, pf_ratio, serum_ph, multiple_seizures, and urine are accepted when documented. Use the prepaid API when a health-education SaaS, electronic worksheet, or school LMS needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with your own SNAPPE-II or mortality model if you need perinatal extensions—this calculator stops at the six physiology items. The product never contacts a laboratory, never invents a random score, and never stamps a clock into the payload.
Integration use cases
Neonatal nursing and medical-school SNAP-II homework
Students submit worst first-12-hour mean BP, temperature, PaO2/FiO2, pH, seizures, and urine output, then pin expected score and breakdown JSON in automated checkers.
Health-education SaaS backends
Server pipelines that already store first-day vitals, blood gas, and urine output call a prepaid endpoint instead of duplicating the 2001 SNAP-II bands in every language.