Free Public Calculator REST API
Integrate science-backed calculation models directly into your web, mobile, or backend apps. 100% free with zero authentication required.
API Overview & Base URL
All endpoints are accessible via HTTPS at https://quickcalc.cloud/api/v1/. Requests return JSON responses formatted with standard HTTP status codes.
Headers include Access-Control-Allow-Origin: *, enabling client-side fetch() calls directly from browser apps.
Unauthenticated requests are rate limited to 60 requests per minute per IP address. Response headers report remaining capacity.
Available Endpoints
Body Mass Index (BMI) API
Calculates BMI value, World Health Organization (WHO) category, and healthy weight ranges for given height and weight.
| Parameter | Type | Required | Description |
|---|---|---|---|
| weight | number | Yes | Body weight (e.g. 70 or 154) |
| height | number | Yes | Height in cm (e.g. 175) |
| unit | string | No | 'metric' (default) or 'imperial' |
| heightFt / heightIn | number | No | Imperial height components (if unit=imperial) |
{
"success": true,
"data": {
"bmi": 22.9,
"category": "Normal",
"healthyRange": {
"minBmi": 18.5,
"maxBmi": 24.9,
"minWeightKg": 56.7,
"maxWeightKg": 76.3
},
"inputs": {
"weight": 70,
"weightUnit": "kg",
"height": 175,
"heightUnit": "cm",
"unitSystem": "metric"
}
},
"meta": {
"formula": "BMI = weight (kg) / [height (m)]²",
"standard": "World Health Organization (WHO)",
"privacy": "100% Stateless & Private — No data logged"
}
}Loan & EMI Amortization API
Computes Equal Monthly Installments (EMI), total interest payable, and full annual amortization schedule.
| Parameter | Type | Required | Description |
|---|---|---|---|
| principal | number | Yes | Loan principal amount (e.g. 250000) |
| annualRate | number | Yes | Annual interest percentage (e.g. 6.5) |
| tenure | number | Yes | Duration period (e.g. 30) |
| tenureUnit | string | No | 'years' (default) or 'months' |
{
"success": true,
"data": {
"monthlyEMI": 1579.99,
"totalPayment": 568797.87,
"totalInterestPayable": 318797.87,
"inputs": {
"principal": 250000,
"annualRate": 6.5,
"tenure": 30,
"tenureUnit": "years"
}
},
"meta": {
"formula": "EMI = P × [r(1+r)ⁿ] / [(1+r)ⁿ - 1]",
"standard": "Reducing-Balance Compound Amortization"
}
}Percentage & Change API
Calculates X% of Y, percentage increase/decrease, discount pricing, or part-to-whole proportions.
| Parameter | Type | Required | Description |
|---|---|---|---|
| type | string | No | 'of' (default), 'change', 'discount', or 'proportion' |
| percent / total | number | mode-dependent | For type='of': e.g. percent=20&total=150 |
| initial / final | number | mode-dependent | For type='change': e.g. initial=100&final=125 |
| price / discount | number | mode-dependent | For type='discount': e.g. price=80&discount=25 |
{
"success": true,
"data": {
"type": "percentage_change",
"percentChange": 25,
"direction": "increase",
"difference": 25,
"inputs": {
"initial": 100,
"final": 125
}
},
"meta": {
"formula": "% Change = [(125 - 100) / 100] * 100 = 25%"
}
}Live Currency Conversion API
Converts fiat currency amounts using real-time mid-market exchange rates without spreads or bank fees.
| Parameter | Type | Required | Description |
|---|---|---|---|
| amount | number | No | Amount to convert (default 1) |
| from | string | Yes | 3-letter source currency code (e.g. USD) |
| to | string | Yes | 3-letter target currency code (e.g. EUR) |
{
"success": true,
"data": {
"amount": 100,
"fromCurrency": "USD",
"toCurrency": "EUR",
"convertedAmount": 91.74,
"exchangeRate": 0.9174,
"inverseRate": 1.09
},
"meta": {
"standard": "European Central Bank (ECB) Mid-Market Benchmark"
}
}Tip & Bill Splitter API
Calculates total tip amounts, grand totals, and symmetric per-person bill splits.
| Parameter | Type | Required | Description |
|---|---|---|---|
| bill | number | Yes | Total pre-tip bill amount (e.g. 100) |
| tip | number | No | Tip percentage (e.g. 18, default 15) |
| people | number | No | Number of people splitting (default 1) |
{
"success": true,
"data": {
"tipAmount": 18.00,
"totalBill": 118.00,
"tipPerPerson": 4.50,
"totalPerPerson": 29.50,
"inputs": {
"billAmount": 100,
"tipPercentage": 18,
"peopleCount": 4
}
},
"meta": {
"formula": "Tip = Bill × (Tip % / 100) | Per Person = (Bill + Tip) / Headcount"
}
}Built something cool with our API? Let us know!
Whether you built a mobile app, browser extension, or SaaS integration, we would love to feature your project in our developer showcase and link back to your site.