Measure the exact span between two dates in days, months, and years.
Date Calculator computes the difference between two calendar dates in minutes, hours, days, weeks, months, and years. Supply start and end dates in YYYY-MM-DD format to receive exact interval breakdowns.
Try it — live request, no key required
No key required to try it. Get a key to use it in your app.
{
"status": "ok",
"error": null,
"data": {
"minutes": 524160,
"hours": 8736,
"days": 364,
"weeks": 52,
"months": 11,
"years": 0,
"start": {
"date": "2022-01-01",
"day": "Saturday",
"month": "January",
"year": "2022",
"words": "Saturday, January 1st 2022"
},
"end": {
"date": "2022-12-31",
"day": "Saturday",
"month": "December",
"year": "2022",
"words": "Saturday, December 31st 2022"
}
}
}
About the Date Calculator API
Date Calculator works by analyzing the dates provided and calculating the date difference. It uses advanced algorithms to calculate the date difference based on the dates and returns the calculated date difference.
What people use it for
- Billing Cycle Tracking
- Subscription management platforms calculate elapsed days and months between customer signup dates and renewal periods to generate accurate prorated invoices.
- Milestone Deadline Tracking
- When managing sprint deadlines, engineering tools track remaining weeks and days against delivery targets to flag overdue milestones.
- Hotel Stay Calculation
- Booking engines compute total nights and days between check-in and check-out dates to present stay lengths and determine nightly rate totals.
- Insurance Policy Eligibility
- To determine policy eligibility, insurance portals calculate the total years and months between an incident date and policy inception.
Ways to call it
One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.
- JSON
- Default REST response
- XML
- Markup format
- YAML
- Human-readable
- CSV
- Tabular export
- GraphQL
- Query language
- MCP
- For AI agents
Other ways to use Date Calculator
Same data, same APIVerve account, same credit balance — one key works on all of them.
What units of time difference does the API return?
Which plan fits 25,000 date calculations a month?
Are day and month names included on the Free plan?
What date format does the API accept?
Does it calculate time spans across multiple years?
Request parameters — GET /v1/datecalculator
Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.
Required
| Parameter | Type | Example | Description |
|---|---|---|---|
startRequired | string | 2022-01-01 | The start date for calculating the difference (format: YYYY-MM-DD) date |
endRequired | string | 2024-08-31 | The end date for calculating the difference (format: YYYY-MM-DD) date |
curl "https://api.apiverve.com/v1/datecalculator?start=2022-01-01&end=2022-12-31" \
-H "x-api-key: YOUR_API_KEY"Authentication
Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.
| Header | When | Value |
|---|---|---|
x-api-keyRequired | Every request | Your API key. Header names are case-insensitive, so X-API-Key is the same header. |
AuthorizationAlternate | Instead of the above | Bearer <key> — for clients that only expose bearer auth. Resolves to the same account and the same billing. |
A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.
Response — GET /v1/datecalculator
Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.
{
"status": "ok",
"error": null,
"data": {
"minutes": 524160,
"hours": 8736,
"days": 364,
"weeks": 52,
"months": 11,
"years": 0,
"start": {
"date": "2022-01-01",
"day": "Saturday",
"month": "January",
"year": "2022",
"words": "Saturday, January 1st 2022"
},
"end": {
"date": "2022-12-31",
"day": "Saturday",
"month": "December",
"year": "2022",
"words": "Saturday, December 31st 2022"
}
}
}
Response fields
Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.
| Field | Type | Example | Description |
|---|---|---|---|
minutes | number | 524160 | Total number of minutes between start and end dates |
hours | number | 8736 | Total number of hours between start and end dates |
days | number | 364 | Total number of days between start and end dates |
weeks | number | 52 | Total number of weeks between start and end dates |
months | number | 11 | Total number of months between start and end dates |
years | number | 0 | Total number of years between start and end dates |
start | object | {...} | The start date, broken into its formatted parts |
date | string | "2022-01-01" | Formatted start date in YYYY-MM-DD format |
dayPremium | string | "Saturday" | Day of week name for the start date |
monthPremium | string | "January" | Month name for the start date |
year | string | "2022" | Year for the start date |
wordsPremium | string | "Saturday, January 1st 2022" | Human-readable formatted start date with day and month |
end | object | {...} | The end date, broken into its formatted parts |
date | string | "2022-12-31" | Formatted end date in YYYY-MM-DD format |
dayPremium | string | "Saturday" | Day of week name for the end date |
monthPremium | string | "December" | Month name for the end date |
year | string | "2022" | Year for the end date |
wordsPremium | string | "Saturday, December 31st 2022" | Human-readable formatted end date with day and month |
Response headers
Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.
| Header | What it carries |
|---|---|
x-api-remaining-credits | Credits left in the current cycle |
x-api-credits-used | Credits spent in the current cycle |
x-api-max-credits | The allowance for the cycle |
x-api-version | Version of the endpoint that answered |
Errors
Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.
| Status | Meaning | What to do |
|---|---|---|
400 | Input was rejected | Read error; it names the parameter that has to change. |
401 | Key missing or invalid | Check the header name and the key value. |
403 | Key valid, but not permitted here | A key restriction or an IP allow-list — never a bad key. |
429 | Rate limited, or out of credits | Read error to tell them apart, then back off or top up. |
What a call costs — 2 credits per call
Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.
| Plan | Per month | Credits | Date Calculator calls | Per 1,000 calls |
|---|---|---|---|---|
| Free | Free | 200 | 100 | Free |
| Starter | $29.99 | 200,000 | 100,000 | $0.30 |
| Pro | $99.99 | 1,000,000 | 500,000 | $0.20 |
| Mega | $299.99 | 4,000,000 | 2,000,000 | $0.15 |
Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.
Call it from cURL — GET /v1/datecalculator
No SDK to install — this is a plain HTTPS call to /v1/datecalculator with your key in the x-api-key header. Swap in a real key and it runs as-is.
curl "https://api.apiverve.com/v1/datecalculator" \
-H "x-api-key: YOUR_API_KEY"Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Node.js — GET /v1/datecalculator
Install the Node.js SDK, then call the Date Calculator API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
npm install @apiverve/datecalculatorconst res = await fetch("https://api.apiverve.com/v1/datecalculator", {
headers: { "x-api-key": "YOUR_API_KEY" },
});
const { data } = await res.json();
console.log(data);Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Python — GET /v1/datecalculator
Install the Python SDK, then call the Date Calculator API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
pip install apiverve-datecalculatorimport requests
res = requests.get(
"https://api.apiverve.com/v1/datecalculator",
headers={"x-api-key": "YOUR_API_KEY"},
)
print(res.json()["data"])Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from C# / .NET — GET /v1/datecalculator
Install the C# / .NET SDK, then call the Date Calculator API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
dotnet add package APIVerve.API.DateCalculatorusing var client = new HttpClient();
client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");
var json = await client.GetStringAsync("https://api.apiverve.com/v1/datecalculator");
Console.WriteLine(json);Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Go — GET /v1/datecalculator
No SDK to install — this is a plain HTTPS call to /v1/datecalculator with your key in the x-api-key header. Swap in a real key and it runs as-is.
req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/datecalculator", nil)
req.Header.Set("x-api-key", "YOUR_API_KEY")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from PHP — GET /v1/datecalculator
No SDK to install — this is a plain HTTPS call to /v1/datecalculator with your key in the x-api-key header. Swap in a real key and it runs as-is.
$ch = curl_init("https://api.apiverve.com/v1/datecalculator");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-api-key: YOUR_API_KEY"]);
$response = curl_exec($ch);
echo $response;Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Ruby — GET /v1/datecalculator
No SDK to install — this is a plain HTTPS call to /v1/datecalculator with your key in the x-api-key header. Swap in a real key and it runs as-is.
require "net/http"
uri = URI("https://api.apiverve.com/v1/datecalculator")
req = Net::HTTP::Get.new(uri)
req["x-api-key"] = "YOUR_API_KEY"
res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
puts res.bodyResources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Zero-code embed — one snippet, no backend
Drop an interactive Date Calculator form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.
Changelog — Date Calculator API
Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.
Entries are picked up from dated catalog snapshots, so the first one appears after the next snapshot that moves something. A period where nothing changed produces no entry — silence is a valid changelog for the Date Calculator API.
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