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-sleutel ophalen Credits kopen

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 % Beschikbaarheid

7ms Antwoord

20 req/s

0.001 Credits / verzoek

Calculate


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

Parameter	Type	Verpl.	Beschrijving
`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"})

Voorbeeld

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": {}
}'

Antwoordvoorbeeld

{
  "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
}

Antwoordcodes

Code	Beschrijving
200 Success	Verzoek succesvol verwerkt.
400 Bad Request	Invoervalidatie mislukt.
401 Unauthorized	Ontbrekende / onjuiste API-sleutel.
403 Forbidden	Sleutel inactief of niet toegestaan.
429 Rate Limit	Te veel verzoeken.
500 Server Error	Onverwachte fout.

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	Type	Verpl.	Beschrijving
`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)

Voorbeeld

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
}'

Antwoordvoorbeeld

{
  "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
}

Antwoordcodes

Code	Beschrijving
200 Success	Verzoek succesvol verwerkt.
400 Bad Request	Invoervalidatie mislukt.
401 Unauthorized	Ontbrekende / onjuiste API-sleutel.
403 Forbidden	Sleutel inactief of niet toegestaan.
429 Rate Limit	Te veel verzoeken.
500 Server Error	Onverwachte fout.

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	Type	Verpl.	Beschrijving
`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)

Voorbeeld

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

Antwoordvoorbeeld

{
  "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
}

Antwoordcodes

Code	Beschrijving
200 Success	Verzoek succesvol verwerkt.
400 Bad Request	Invoervalidatie mislukt.
401 Unauthorized	Ontbrekende / onjuiste API-sleutel.
403 Forbidden	Sleutel inactief of niet toegestaan.
429 Rate Limit	Te veel verzoeken.
500 Server Error	Onverwachte fout.

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	Type	Verpl.	Beschrijving
`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)

Voorbeeld

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
}'

Antwoordvoorbeeld

{
  "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
}

Antwoordcodes

Code	Beschrijving
200 Success	Verzoek succesvol verwerkt.
400 Bad Request	Invoervalidatie mislukt.
401 Unauthorized	Ontbrekende / onjuiste API-sleutel.
403 Forbidden	Sleutel inactief of niet toegestaan.
429 Rate Limit	Te veel verzoeken.
500 Server Error	Onverwachte fout.

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 mrt. 2026, 05:37 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.

Veelgestelde vragen

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. Elk verzoek, zelfs die met fouten, verbruikt credits. Uw credits zijn gekoppeld aan het aantal verzoeken, ongeacht succes of falen. Als de fout duidelijk te wijten is aan een platformprobleem aan onze kant, herstellen we de getroffen credits (geen geldteruggave).

Neem contact met ons op via [email protected]. We nemen feedback serieus—als uw bugrapport of functieverzoek zinvol is, kunnen we de API snel repareren of verbeteren en u 50 gratis credits geven als dank.

Het hangt af van de API en soms zelfs van het endpoint. Sommige endpoints gebruiken gegevens van externe bronnen, die strengere limieten kunnen hebben. We handhaven ook limieten om misbruik te voorkomen en ons platform stabiel te houden. Raadpleeg de documentatie voor de specifieke limiet van elk endpoint.

We werken met een creditsysteem. Credits zijn vooruitbetaalde, niet-restitueerbare eenheden die u besteedt aan API-aanroepen en tools. Credits worden verbruikt volgens FIFO (oudste eerst) en zijn geldig voor 12 maanden vanaf de aankoopdatum. Het dashboard toont elke aankoopdatum en de vervaldatum.

Ja. Alle gekochte credits (inclusief fractionele saldi) zijn geldig voor 12 maanden na aankoop. Ongebruikte credits verlopen automatisch en worden permanent verwijderd aan het einde van de geldigheidsperiode. Verlopen credits kunnen niet worden hersteld of omgezet in contant geld of andere waarde. Overgangsregel: credits gekocht vóór 22 sep. 2025 worden behandeld als gekocht op 22 sep. 2025 en verlopen op 22 sep. 2026 (tenzij een eerdere vervaldatum werd vermeld bij aankoop).

Ja—binnen hun geldigheidsperiode. Ongebruikte credits blijven beschikbaar en worden van maand tot maand overgedragen totdat ze 12 maanden na aankoop verlopen.

Credits zijn niet-restitueerbaar. Koop alleen wat u nodig heeft—u kunt altijd later bijvullen. Als een platformfout een mislukte afschrijving veroorzaakt, kunnen we de getroffen credits herstellen na onderzoek. Geen geldteruggave.

Prijzen worden vastgesteld in credits, niet in dollars. Elk endpoint heeft zijn eigen kosten—zie de badge "Credits / verzoek" hierboven. U weet altijd precies wat u uitgeeft.

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Verkrijg credits om premium inhoud en functies te ontgrendelen

Klanttype

Factureringsland

API / Eindpunt

Valuta

Aantal verzoeken

Calculator API — 135+ Online Calculators | YEB

Try it live

Calculate

Voorbeeld

Antwoordvoorbeeld

Antwoordcodes

Calculate

Parameters

Code Samples

Response

List Calculators

Voorbeeld

Antwoordvoorbeeld

Antwoordcodes

List Calculators

Parameters

Code Samples

Response

Calculator Info

Voorbeeld

Antwoordvoorbeeld

Antwoordcodes

Calculator Info

Parameters

Code Samples

Response

Search Calculators

Voorbeeld

Antwoordvoorbeeld

Antwoordcodes

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

Veelgestelde vragen

What calculators are available?

How much does it cost?

What languages are supported?

Can I get the formula definition?

How does unit conversion work?

Tellen verzoeken met fouten mee en kosten ze credits?

Ik heb een bug gevonden of wil aanpassingen in de API's. Wat moet ik doen?

Wat is de snelheidslimiet?

Hoe werken betaling en gebruik?

Verlopen credits?

Worden ongebruikte credits overgedragen?

Bieden jullie restituties aan?

Hoeveel kost elke API-aanroep?