Calculator API — 135+ Online Calculators | YEB

135+ online calculators via REST API. Finance, health, math, construction, physics and more. Evaluate formulas, search calculators, get definitions.

API FAQ

API-Schlüssel erhalten Credits kaufen

Try it live

All 135 calculators are available for free on the web app:

Open calculator.yeb.to

✓

135+ calculators
Finance, health, math, construction, physics, chemistry, biology, statistics, and more.

✓

16 categories
Organized by topic for easy discovery and integration.

✓

30 languages
Translated titles, descriptions, and input/output labels.

Endpoint:

99.9 % Verfügbarkeit

7ms Antwort

20 req/s

0.001 Credits / Anfrage

Calculate


POST https://api.yeb.to/v1/calculator/calculate

Parameter	Typ	Erf.	Beschreibung
`api_key`	string	ja	Your API key
`calculator_id`	integer	ja	ID of the calculator to evaluate
`inputs`	object	ja	Input values as key-value pairs (e.g. {"length": 10, "width": 5})
`units`	object	opt.	Selected units per input/output (e.g. {"length": "m", "area": "m2"})

Beispiel

curl -X POST https://api.yeb.to/v1/calculator/calculate \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "calculator_id": 1,
  "inputs": {
    "value": 200,
    "percentage": 15
  },
  "units": {}
}'

Antwortbeispiel

{
  "calculator_id": 1,
  "calculator_slug": "percentage",
  "results": {
    "result": {
      "value": 30,
      "unit": null
    },
    "inverse": {
      "value": 7.5,
      "unit": null
    }
  },
  "credits_spent": 0.001,
  "credits_left": 99.99,
  "response_code": 200,
  "response_time_ms": 12
}

{
  "error": "Calculator not found",
  "response_code": 404,
  "response_time_ms": 3
}

Antwortcodes

Code	Beschreibung
200 Success	Anfrage erfolgreich verarbeitet.
400 Bad Request	Eingabevalidierung fehlgeschlagen.
401 Unauthorized	Fehlender / falscher API-Schlüssel.
403 Forbidden	Schlüssel inaktiv oder nicht erlaubt.
429 Rate Limit	Zu viele Anfragen.
500 Server Error	Unerwarteter Fehler.

Calculate

calculator/calculate 0.0010 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Calculator ID

body · string · required

Inputs

body · string · required

Units

body · string

Code Samples

Response

Status: —

Headers

Body

List Calculators


POST https://api.yeb.to/v1/calculator/list

Parameter	Typ	Erf.	Beschreibung
`api_key`	string	ja	Your API key
`category`	string	opt.	Filter by category slug (e.g. "finance", "health", "math")
`locale`	string	opt.	Language code for translated titles (default: en)
`limit`	integer	opt.	Max results, 1–100 (default: 50)
`offset`	integer	opt.	Skip N results for pagination (default: 0)

Beispiel

curl -X POST https://api.yeb.to/v1/calculator/list \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "category": "finance",
  "locale": "en",
  "limit": 5
}'

Antwortbeispiel

{
  "total": 14,
  "offset": 0,
  "limit": 5,
  "calculators": [
    {
      "id": 1,
      "slug": "percentage",
      "title": "Percentage Calculator",
      "short_description": "Calculate what X% of Y is.",
      "category": "finance"
    },
    {
      "id": 2,
      "slug": "percentage-change",
      "title": "Percentage Change Calculator",
      "short_description": "Calculate percentage change between two values.",
      "category": "finance"
    }
  ],
  "credits_spent": 0,
  "credits_left": 100,
  "response_code": 200,
  "response_time_ms": 8
}

{
  "error": "Invalid limit parameter",
  "response_code": 400,
  "response_time_ms": 2
}

Antwortcodes

Code	Beschreibung
200 Success	Anfrage erfolgreich verarbeitet.
400 Bad Request	Eingabevalidierung fehlgeschlagen.
401 Unauthorized	Fehlender / falscher API-Schlüssel.
403 Forbidden	Schlüssel inaktiv oder nicht erlaubt.
429 Rate Limit	Zu viele Anfragen.
500 Server Error	Unerwarteter Fehler.

List Calculators

calculator/list 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Code Samples

Response

Status: —

Headers

Body

Calculator Info


POST https://api.yeb.to/v1/calculator/info

Parameter	Typ	Erf.	Beschreibung
`api_key`	string	ja	Your API key
`slug`	string	opt.	Calculator slug (e.g. "bmi", "mortgage")
`calculator_id`	integer	opt.	Calculator ID (alternative to slug)
`locale`	string	opt.	Language code (default: en)

Beispiel

curl -X POST https://api.yeb.to/v1/calculator/info \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "slug": "bmi"
}'

Antwortbeispiel

{
  "id": 25,
  "slug": "bmi",
  "title": "BMI Calculator",
  "short_description": "Calculate your Body Mass Index.",
  "formula": {
    "inputs": [
      {"key": "weight", "type": "number", "default": 70, "unit_group": "mass", "default_unit": "kg"},
      {"key": "height", "type": "number", "default": 175, "unit_group": "height", "default_unit": "cm"}
    ],
    "outputs": [
      {"key": "bmi", "expression": "weight / (height * height)", "precision": 1},
      {"key": "category", "expression": "..."}
    ],
    "unit_groups": {
      "mass": {"kg": 1, "lb": 0.453592},
      "height": {"m": 1, "cm": 0.01, "in": 0.0254}
    }
  },
  "input_labels": {"weight": "Weight", "height": "Height"},
  "output_labels": {"bmi": "Your BMI", "category": "Category"},
  "category": {"slug": "health", "name": "Health & Fitness"},
  "credits_spent": 0,
  "response_code": 200
}

{
  "error": "Calculator not found",
  "response_code": 404,
  "response_time_ms": 3
}

Antwortcodes

Code	Beschreibung
200 Success	Anfrage erfolgreich verarbeitet.
400 Bad Request	Eingabevalidierung fehlgeschlagen.
401 Unauthorized	Fehlender / falscher API-Schlüssel.
403 Forbidden	Schlüssel inaktiv oder nicht erlaubt.
429 Rate Limit	Zu viele Anfragen.
500 Server Error	Unerwarteter Fehler.

Calculator Info

calculator/info 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Slug

body · string

Calculator ID

body · string

Locale

body · string

Code Samples

Response

Status: —

Headers

Body

Search Calculators


POST https://api.yeb.to/v1/calculator/search

Parameter	Typ	Erf.	Beschreibung
`api_key`	string	ja	Your API key
`query`	string	ja	Search query (minimum 2 characters)
`locale`	string	opt.	Language code (default: en)
`limit`	integer	opt.	Max results, 1–50 (default: 20)

Beispiel

curl -X POST https://api.yeb.to/v1/calculator/search \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "query": "mortgage",
  "locale": "en",
  "limit": 5
}'

Antwortbeispiel

{
  "query": "mortgage",
  "results": [
    {
      "id": 5,
      "slug": "mortgage",
      "title": "Mortgage Calculator",
      "short_description": "Calculate monthly mortgage payment, total interest, and total amount paid.",
      "category": "finance"
    },
    {
      "id": 9,
      "slug": "amortization",
      "title": "Amortization Calculator",
      "short_description": "See how each payment splits between principal and interest.",
      "category": "finance"
    }
  ],
  "credits_spent": 0,
  "response_code": 200,
  "response_time_ms": 15
}

{
  "error": "Query must be at least 2 characters",
  "response_code": 400,
  "response_time_ms": 2
}

Antwortcodes

Code	Beschreibung
200 Success	Anfrage erfolgreich verarbeitet.
400 Bad Request	Eingabevalidierung fehlgeschlagen.
401 Unauthorized	Fehlender / falscher API-Schlüssel.
403 Forbidden	Schlüssel inaktiv oder nicht erlaubt.
429 Rate Limit	Zu viele Anfragen.
500 Server Error	Unerwarteter Fehler.

Search Calculators

calculator/search 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Query

body · string · required

Locale

body · string

Limit

body · string

Code Samples

Response

Status: —

Headers

Body

Calculator API — 135+ Online Calculators | YEB — Practical Guide

A hands-on guide to the Calculator API: 135+ online calculators across 16 categories, formula evaluation with unit conversion, multilingual support in 30 languages, and how to integrate it all into your application.

Last updated: 21 Mär 2026, 00:21 API Version: v1 Burst: 20 req/s Latency: 7 ms

#What the Calculator API does

The Calculator API provides 4 endpoints for accessing 135+ online calculators: evaluate formulas with unit conversion, list and search calculators, and get complete formula definitions — all via simple POST requests.

Key advantage: three out of four endpoints are completely free. Only the Calculate endpoint costs credits (0.001 per request). Formula definitions are open, so you can also evaluate client-side if preferred.

#Endpoints at a glance

Endpoint	What it does	Credits
`POST /v1/calculator/calculate`	Evaluate a calculator formula with inputs and unit conversion	0.001
`POST /v1/calculator/list`	List all calculators, optionally filtered by category	FREE
`POST /v1/calculator/info`	Get full formula definition, inputs, outputs, and unit groups	FREE
`POST /v1/calculator/search`	Search calculators by keyword across all categories	FREE

#Available categories

135 calculators are organized into 16 categories:

Category	Slug	Count	Examples
Finance	`finance`	14	Percentage, Mortgage, Compound Interest, ROI, CAGR
Salary & Tax	`salary-tax`	10	Gross/Net, VAT, Tip, Discount, Margin, Retirement
Health & Fitness	`health`	12	BMI, Calories (TDEE), BMR, Body Fat, Protein
Pregnancy	`pregnancy`	5	Due Date, Ovulation, Period, Fertility Window
Math	`math`	10	Fraction, Quadratic Formula, GPA, Logarithm
Conversion	`conversion`	10	Weight, Length, Temperature, Speed, Pressure
Time & Date	`time-date`	7	Age, Days Between Dates, Countdown, Time Zone
Construction	`construction`	9	Concrete, Brick, Tile, Paint, Roofing
Automotive	`automotive`	8	Fuel Cost, Tire Size, Horsepower, 0-100 km/h
Physics	`physics`	8	Free Fall, Force, Kinetic Energy, Projectile Motion
Chemistry	`chemistry`	7	Molar Mass, pH, Dilution, Percent Yield
Biology	`biology`	6	Punnett Square, DNA, Bacteria Growth
Statistics	`statistics`	8	Std Deviation, Confidence Interval, Z-Score
Food & Cooking	`food`	8	Pizza, Coffee, Grams to Cups, Recipe Scaler
Sports	`sports`	7	Calories Burned, Pace, Marathon, VO2 Max
Fun & Viral	`fun`	6	Love Compatibility, Lucky Number, Zodiac

#How the formula system works

Each calculator stores its formula as a JSON definition with inputs, outputs, unit groups, and constants. The formula engine supports arithmetic, ternary expressions, and built-in math functions (sqrt, sin, cos, log, pow, min, max, etc.).

Use the info endpoint to retrieve the complete formula definition for any calculator. You can then evaluate it server-side via the calculate endpoint, or implement client-side evaluation using the same expression language.

Unit conversion is automatic. Define unit groups (e.g. length: m, cm, ft, in) with conversion factors. Inputs are normalized to base units before evaluation, and outputs are converted to the user's selected display unit.

#Multilingual support

All 135 calculators are translated into 30 languages: English, Bulgarian, Spanish, German, French, Italian, Portuguese, Russian, Polish, Dutch, Turkish, Czech, Romanian, Hungarian, Ukrainian, Swedish, Danish, Finnish, Norwegian, Greek, Arabic, Hebrew, Japanese, Korean, Chinese (Simplified & Traditional), Thai, Vietnamese, Indonesian, and Malay.

Use the locale parameter on the list, info, and search endpoints to get translated titles, descriptions, input/output labels, and educational content.

#Common use cases

Embedded calculators — add interactive calculators to your website or app
Education platforms — provide step-by-step calculations for students
Health & fitness apps — BMI, calorie, and body composition calculations
Real estate tools — mortgage, loan, and amortization calculations
Construction estimators — material quantity and cost calculators
Chatbots & AI assistants — answer calculation questions programmatically
Comparison tools — evaluate multiple scenarios with different inputs

#Try it live

All 135 calculators are available for free on calculator.yeb.to. Each calculator has an interactive widget, educational article, FAQ section, and SEO-optimized pages in 30 languages. The web app uses the same formula engine as the API.

Häufig gestellte Fragen

135+ calculators across 16 categories: finance (percentage, mortgage, compound interest, ROI), health (BMI, calories, body fat), math (quadratic formula, logarithm), construction (concrete, brick, tile), physics (free fall, kinetic energy), chemistry (molar mass, pH), and more.

The Calculate endpoint costs 0.001 credits per request. List, Info, and Search endpoints are completely free. Sign up to get free credits.

All 135 calculators are translated into 30 languages including English, Spanish, German, French, Bulgarian, Russian, Japanese, Chinese, Arabic, and more. Use the locale parameter to get translated content.

Yes! Use the Info endpoint with a calculator slug to get the complete formula definition including inputs, outputs, expressions, unit groups, and constants. You can evaluate formulas client-side or via the Calculate endpoint.

Each calculator defines unit groups with conversion factors. When you send a units parameter with your Calculate request, inputs are automatically converted to base units before evaluation, and outputs are converted to your selected display units.

Ja. Jede Anfrage, auch solche mit Fehlern, verbraucht Credits. Ihre Credits sind an die Anzahl der Anfragen gebunden, unabhängig von Erfolg oder Misserfolg. Wenn der Fehler eindeutig auf ein Plattformproblem unsererseits zurückzuführen ist, stellen wir die betroffenen Credits wieder her (keine Barerstattung).

Kontaktieren Sie uns unter [email protected]. Wir nehmen Feedback ernst—wenn Ihr Fehlerbericht oder Ihre Funktionsanfrage sinnvoll ist, können wir die API schnell korrigieren oder verbessern und Ihnen 50 kostenlose Credits als Dankeschön gewähren.

Es hängt von der API und manchmal sogar vom Endpoint ab. Einige Endpoints nutzen Daten aus externen Quellen, die strengere Limits haben können. Wir setzen auch Limits durch, um Missbrauch zu verhindern und unsere Plattform stabil zu halten. Prüfen Sie die Dokumentation für das spezifische Limit jedes Endpoints.

Wir arbeiten mit einem Creditsystem. Credits sind vorausbezahlte, nicht erstattungsfähige Einheiten, die Sie für API-Aufrufe und Tools ausgeben. Credits werden nach dem FIFO-Prinzip (älteste zuerst) verbraucht und sind 12 Monate ab Kaufdatum gültig. Das Dashboard zeigt jedes Kaufdatum und dessen Ablauf an.

Ja. Alle gekauften Credits (einschließlich Teilguthaben) sind 12 Monate ab Kauf gültig. Ungenutzte Credits verfallen automatisch und werden am Ende der Gültigkeitsdauer dauerhaft gelöscht. Verfallene Credits können nicht wiederhergestellt oder in Bargeld oder anderen Wert umgewandelt werden. Übergangsregel: Vor dem 22. Sep. 2025 gekaufte Credits gelten als am 22. Sep. 2025 gekauft und verfallen am 22. Sep. 2026 (sofern beim Kauf kein früherer Ablauf angegeben wurde).

Ja—innerhalb ihrer Gültigkeitsdauer. Ungenutzte Credits bleiben verfügbar und werden von Monat zu Monat übertragen, bis sie 12 Monate nach dem Kauf verfallen.

Credits sind nicht erstattungsfähig. Kaufen Sie nur, was Sie brauchen—Sie können jederzeit nachladen. Wenn ein plattformseitiger Fehler eine fehlgeschlagene Abbuchung verursacht, können wir die betroffenen Credits nach Prüfung wiederherstellen. Keine Barerstattung.

Preise werden in Credits angegeben, nicht in Dollar. Jeder Endpoint hat seine eigenen Kosten—siehe das Abzeichen „Credits / Anfrage" oben. Sie wissen immer genau, was Sie ausgeben.

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Calculator API — 135+ Online Calculators | YEB

Try it live

Calculate

Beispiel

Antwortbeispiel

Antwortcodes

Calculate

Parameters

Code Samples

Response

List Calculators

Beispiel

Antwortbeispiel

Antwortcodes

List Calculators

Parameters

Code Samples

Response

Calculator Info

Beispiel

Antwortbeispiel

Antwortcodes

Calculator Info

Parameters

Code Samples

Response

Search Calculators

Beispiel

Antwortbeispiel

Antwortcodes

Search Calculators

Parameters

Code Samples

Response

Calculator API — 135+ Online Calculators | YEB — Practical Guide

#What the Calculator API does

#Endpoints at a glance

#Available categories

#How the formula system works

#Multilingual support

#Common use cases

#Try it live

Häufig gestellte Fragen

What calculators are available?

How much does it cost?

What languages are supported?

Can I get the formula definition?

How does unit conversion work?

Zählen fehlerhafte Anfragen und kosten sie Credits?

Ich habe einen Fehler gefunden oder möchte Anpassungen an den APIs. Was soll ich tun?

Was ist das Anfragelimit?

Wie funktioniert Bezahlung und Nutzung?

Verfallen Credits?

Werden ungenutzte Credits übertragen?

Bieten Sie Erstattungen an?

Wie viel kostet jeder API-Aufruf?