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

Obtenir une clé API Acheter des crédits

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 % Disponibilité

7ms Réponse

20 req/s

0.001 Crédits / requête

Calculate


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

Paramètre	Type	Req.	Description
`api_key`	string	oui	Your API key
`calculator_id`	integer	oui	ID of the calculator to evaluate
`inputs`	object	oui	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"})

Exemple

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": {}
}'

Exemple de réponse

{
  "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
}

Codes de réponse

Code	Description
200 Success	Requête traitée avec succès.
400 Bad Request	Validation d'entrée échouée.
401 Unauthorized	Clé API manquante ou incorrecte.
403 Forbidden	Clé inactive ou non autorisée.
429 Rate Limit	Trop de requêtes.
500 Server Error	Erreur inattendue.

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

Paramètre	Type	Req.	Description
`api_key`	string	oui	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)

Exemple

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
}'

Exemple de réponse

{
  "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
}

Codes de réponse

Code	Description
200 Success	Requête traitée avec succès.
400 Bad Request	Validation d'entrée échouée.
401 Unauthorized	Clé API manquante ou incorrecte.
403 Forbidden	Clé inactive ou non autorisée.
429 Rate Limit	Trop de requêtes.
500 Server Error	Erreur inattendue.

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

Paramètre	Type	Req.	Description
`api_key`	string	oui	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)

Exemple

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

Exemple de réponse

{
  "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
}

Codes de réponse

Code	Description
200 Success	Requête traitée avec succès.
400 Bad Request	Validation d'entrée échouée.
401 Unauthorized	Clé API manquante ou incorrecte.
403 Forbidden	Clé inactive ou non autorisée.
429 Rate Limit	Trop de requêtes.
500 Server Error	Erreur inattendue.

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

Paramètre	Type	Req.	Description
`api_key`	string	oui	Your API key
`query`	string	oui	Search query (minimum 2 characters)
`locale`	string	opt.	Language code (default: en)
`limit`	integer	opt.	Max results, 1–50 (default: 20)

Exemple

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
}'

Exemple de réponse

{
  "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
}

Codes de réponse

Code	Description
200 Success	Requête traitée avec succès.
400 Bad Request	Validation d'entrée échouée.
401 Unauthorized	Clé API manquante ou incorrecte.
403 Forbidden	Clé inactive ou non autorisée.
429 Rate Limit	Trop de requêtes.
500 Server Error	Erreur inattendue.

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 mars 2026, 00:15 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.

Questions fréquemment posées

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.

Oui. Chaque requête, même celles qui entraînent des erreurs, consomme des crédits. Vos crédits sont liés au nombre de requêtes, indépendamment du succès ou de l'échec. Si l'erreur est clairement due à un problème de plateforme de notre côté, nous restaurerons les crédits affectés (pas de remboursement en espèces).

Contactez-nous à [email protected]. Nous prenons les retours au sérieux—si votre rapport de bug ou demande de fonctionnalité est pertinent, nous pouvons corriger ou améliorer l'API rapidement et vous accorder 50 crédits gratuits en guise de remerciement.

Cela dépend de l'API et parfois même du endpoint. Certains endpoints utilisent des données de sources externes, qui peuvent avoir des limites plus strictes. Nous imposons également des limites pour prévenir les abus et maintenir la stabilité de notre plateforme. Consultez la documentation pour la limite spécifique de chaque endpoint.

Nous fonctionnons avec un système de crédits. Les crédits sont des unités prépayées et non remboursables que vous dépensez pour les appels API et les outils. Les crédits sont consommés en FIFO (les plus anciens en premier) et sont valables 12 mois à compter de la date d'achat. Le tableau de bord affiche chaque date d'achat et son expiration.

Oui. Tous les crédits achetés (y compris les soldes fractionnaires) sont valables 12 mois à compter de l'achat. Les crédits inutilisés expirent automatiquement et sont définitivement supprimés à la fin de la période de validité. Les crédits expirés ne peuvent être restaurés ni convertis en espèces ou autre valeur. Règle transitoire : les crédits achetés avant le 22 sept. 2025 sont traités comme achetés le 22 sept. 2025 et expirent le 22 sept. 2026 (sauf si une expiration antérieure a été indiquée lors de l'achat).

Oui—dans leur période de validité. Les crédits inutilisés restent disponibles et sont reportés de mois en mois jusqu'à leur expiration 12 mois après l'achat.

Les crédits sont non remboursables. N'achetez que ce dont vous avez besoin—vous pouvez toujours recharger plus tard. Si une erreur de plateforme cause un échec de facturation, nous pouvons restaurer les crédits affectés après enquête. Pas de remboursement en espèces.

Les prix sont fixés en crédits, pas en dollars. Chaque endpoint a son propre coût—voir le badge « Crédits / requête » ci-dessus. Vous saurez toujours exactement ce que vous dépensez.

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Type de client

Pays de facturation

API / Endpoint

Devise

Nombre de requêtes

Calculator API — 135+ Online Calculators | YEB

Try it live

Calculate

Exemple

Exemple de réponse

Codes de réponse

Calculate

Parameters

Code Samples

Response

List Calculators

Exemple

Exemple de réponse

Codes de réponse

List Calculators

Parameters

Code Samples

Response

Calculator Info

Exemple

Exemple de réponse

Codes de réponse

Calculator Info

Parameters

Code Samples

Response

Search Calculators

Exemple

Exemple de réponse

Codes de réponse

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

Questions fréquemment posées

What calculators are available?

How much does it cost?

What languages are supported?

Can I get the formula definition?

How does unit conversion work?

Les requêtes avec erreurs comptent-elles et coûtent-elles des crédits ?

J'ai trouvé un bug ou je veux des personnalisations dans les APIs. Que faire ?

Quelle est la limite de requêtes ?

Comment fonctionnent le paiement et l'utilisation ?

Les crédits expirent-ils ?

Les crédits inutilisés sont-ils reportés ?

Proposez-vous des remboursements ?

Combien coûte chaque appel API ?