Urine pregnancy test interpreter
An hCG level of 150 mIU/mL four days after a missed period reads as positive, well above the usual 25 mIU/mL strip cut-off. Enter a measured hormone level and the days since the missed period to get the reading. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Hormone level
- 150
- Days since missed period
- 4
- Result
- positive
- Hormone unit
- mIU/mL
- Strip cutoff
- 25
- Grey zone min
- 5
A urine pregnancy test reads human chorionic gonadotropin in milli-international units per millilitre and, together with how many days have passed since a missed period, decides whether a typical home strip would be positive, negative, or still inconclusive. This interpreter accepts those two numbers, applies published educational cut-offs of five and twenty-five milli-international units per millilitre plus a four-day too-early window, and returns a single result string you can show next to a lab ticket. Use it when you already have a quantitative hormone level and only need a transparent urine-test reading without standing up an obstetric library of your own.
How a urine pregnancy test is classified from hormone level and days
A qualitative urine pregnancy test is a threshold reading of human chorionic gonadotropin, the hormone produced after implantation, expressed in milli-international units per millilitre. Over-the-counter urine strips commonly advertise a detection limit of twenty-five milli-international units per millilitre: a concentration at or above that floor is expected to produce a second line, and a concentration well below it is expected to leave the test line blank.
Clinical laboratory teaching adds a lower floor of five milli-international units per millilitre, below which a result is treated as not pregnant, and a grey zone from five up to but not including twenty-five where a home strip is often too insensitive to decide. This interpreter encodes that three-band split as a deterministic rule, not as a live immunoassay. Days since the missed period enter the rule because human chorionic gonadotropin roughly doubles every forty-eight hours in an early viable pregnancy.
From the missed-period day the educational expected minimum is twenty-five times two raised to the power of days divided by two, which grows the strip floor along that doubling clock. A value below five milli-international units per millilitre is called a reliable negative only when at least four whole days have passed since the missed period; earlier than that, a low reading is still inconclusive because ovulation or implantation may have been late. Grey-zone values stay inconclusive at every day count because they sit below the usual urine detection limit.
Values at or above twenty-five are positive. The calculator is an educational reading aid. It does not diagnose a viable intrauterine pregnancy, rule out ectopic pregnancy, or replace a quantitative blood test or clinical care when bleeding, pain, or risk factors need a clinician.
Where a urine pregnancy-test interpreter earns its keep
People search for a urine pregnancy test interpreter when they already hold a quantitative hormone number from a laboratory ticket or a digital reader and want a transparent positive, negative, or inconclusive reading that also respects how many days have passed since a missed period.
Wellness apps, editorial explainers, and intake forms need a named cut-off they can show next to that search: twenty-five milli-international units per millilitre for a typical strip, five for the laboratory negative floor, and a four-day too-early window so a blank test on the first missed-period day is not sold as a definitive negative. Embedding this calculator gives those bands and a single result string a user interface can render without inventing a doubling model of its own.
Classroom demos of qualitative immunoassay thresholds can change the hormone level and the day count and immediately see result flip from inconclusive to negative at day four, or from grey zone to positive at twenty-five, which is exactly the kind of edge a host clock or a random seed would mishandle. If a reading is inconclusive, the usual teaching is to repeat after forty-eight hours, when a doubling viable pregnancy would have moved.
What you can do with it
Lab-ticket reading next to a missed period
Turn a quantitative urine hCG in mIU/mL plus days since the missed period into a single positive, negative, or inconclusive label a clinic form can store without inventing strip cut-offs.
FAQ
What hormone level makes a urine pregnancy test positive?
Values from 5 up to but not including 25 are inconclusive (grey zone).
Why can a low hormone level still be inconclusive?
A reading below 5 mIU/mL in the first four days after a missed period is too early for a reliable negative, because implantation may have been late. Grey-zone values (5 to less than 25 mIU/mL) stay inconclusive at every day count because they sit below the usual urine strip cutoff.
What is the expected minimum hormone level?
In an early viable pregnancy hCG roughly doubles every 48 hours, so the educational floor is 25 mIU/mL times two to the power of days divided by two. Four days after a missed period that floor is 100 mIU/mL.
Can this reading rule out an ectopic pregnancy?
No. It does not confirm a viable pregnancy in the womb, rule out an ectopic pregnancy or replace a blood test. If there is bleeding, pain or another risk factor, see a clinician.
How do I count the days since my missed period?
Count the first day your period was expected but did not arrive as day zero, then add one for each whole calendar day after it. Only whole days are accepted, not fractions.
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-pregnancy-test \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"hormone_level":150,"days_since_missed_period":4}'const res = await fetch("https://api.kit.forhosting.com/health/urine-pregnancy-test", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"hormone_level": 150,
"days_since_missed_period": 4
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/health/urine-pregnancy-test",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"hormone_level": 150,
"days_since_missed_period": 4
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/urine-pregnancy-test", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"hormone_level":150,"days_since_missed_period":4}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"hormone_level":150,"days_since_missed_period":4}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/urine-pregnancy-test", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"hormone_level": 150,
"days_since_missed_period": 4
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "health.urine_pregnancy_test",
"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_hormone_level | 1000000 |
max_days | 365 |
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 hormone concentrations are physically impossible and fail with invalid_input rather than a fake result.
Input contract, response shape, and the negative-hormone error
Zero is a real laboratory reading of undetectable hormone and is accepted. The value must be an integer from zero through three hundred sixty-five inclusive. Optional output keys are omitted rather than set to null. Invalid input is not billed. POST a JSON object with two required numeric fields. hormone_level is the measured human chorionic gonadotropin concentration in milli-international units per millilitre; aliases hcg, hcg_miu_ml, hormone, and concentration map to the same parse so laboratory tickets and forms can keep their usual names. The value must be a finite number, may arrive as a JSON number or as a strict decimal numeric string, and must not be negative: a concentration below zero is physically impossible and fails with invalid_input naming the field. Concentrations above one million milli-international units per millilitre are rejected as out of the published limit. days_since_missed_period is the whole number of calendar days since the expected period did not arrive, counted as zero on the first missed-period day; aliases days, days_late, missed_days, and days_missed are accepted. Negative day counts and non-integers fail with invalid_input. On success the body echoes the cleaned hormone_level and days_since_missed_period, tags hormone_unit as mIU/mL, reports strip_cutoff twenty-five and grey_zone_min five, returns expected_min as twenty-five times two to the power of days over two rounded to twelve decimal places, sets result to positive, negative, or inconclusive, attaches a machine-readable reason code, and includes a formula string restating the rule. Example: hormone_level one hundred fifty with days_since_missed_period four is positive with reason above_strip_cutoff, because one hundred fifty meets the twenty-five milli-international unit strip. Successful API calls cost $0.002 per item.
Where a urine pregnancy-test interpreter earns its keep
Automation that archives laboratory columns can call the same pure function on the prepaid path at $0.002 per successful request; invalid input does not consume balance. Pin the examples, keep negative concentrations as a hard error, and you get a reproducible urine pregnancy test reading without standing up an obstetric SDK of your own for a two-number problem.
Integration use cases
Editorial explainers and home-test education
Power a live urine-pregnancy-test page whose free browser result matches the API, including the four-day too-early window and a hard rejection of negative hormone concentrations.
QA fixtures and teaching worksheets
Generate known-good positive, grey-zone, too-early, and late-negative cases plus a negative-hormone invalid_input for automated goldens and classroom threshold drills.
Technical questions
What happens if the hormone level is negative?
The task fails with invalid_input. A urine hCG concentration in mIU/mL cannot be below zero, so a negative hormone_level is treated as a client error and is not billed.
What does expected_min mean?
expected_min is an educational lower bound if a viable early pregnancy is present: 25 × 2^(days/2) mIU/mL, which grows the strip floor by the usual forty-eight-hour doubling clock from the missed-period day. It is context, not a personal blood-test result.
What does the urine pregnancy test interpreter cost?
The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.