Loan, savings and investment maths
Compute loan payments, amortisation schedules, future and present values, NPV and IRR with exact arithmetic.
Details
Operations:
- payment: level payment per period. Needs principal, annual_rate_percent, years (or periods).
- schedule: payment, interest and balance per period, rounded to cents like a bank statement (max 1200 periods).
- future_value: needs present_value and/or contribution per period, annual_rate_percent, years.
- present_value: needs future_value, annual_rate_percent, years.
- npv: needs rate_percent per period and cashflows (the first at time 0).
- irr: needs cashflows; returns percent per period.
periods_per_year defaults to 12. Not advice: formulas only.
Price: CHF 0.003 per call (first 100 calls per day free).
Example: {"operation":"payment","principal":"500000","annual_rate_percent":"1.8","years":25} → "2070.93" per month.
Call it
RESTcurl -X POST https://api.tausendwerk.xyz/v1/finance \
-H "Content-Type: application/json" \
-d '{"operation":"payment","principal":"500000","annual_rate_percent":"1.8","years":25}'financeAfter the free 100 calls per day, add a key: Authorization: Bearer tw_live_…. Pricing
Try it
Runs against the live API with the free allowance.
Input schema JSON Schema
{
"type": "object",
"additionalProperties": false,
"required": [
"operation"
],
"properties": {
"operation": {
"type": "string",
"enum": [
"payment",
"schedule",
"future_value",
"present_value",
"npv",
"irr"
]
},
"principal": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"annual_rate_percent": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"rate_percent": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"years": {
"type": "number",
"exclusiveMinimum": 0,
"maximum": 100
},
"periods": {
"type": "integer",
"minimum": 1,
"maximum": 1200
},
"periods_per_year": {
"type": "integer",
"minimum": 1,
"maximum": 365,
"default": 12
},
"present_value": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"future_value": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"contribution": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"cashflows": {
"type": "array",
"items": {
"type": [
"string",
"number"
],
"description": "A number. Send a string such as \"0.1\" to keep it exact."
},
"minItems": 2,
"maxItems": 1200
},
"decimals": {
"type": "integer",
"minimum": 0,
"maximum": 100,
"description": "Round the result to this many decimal places."
},
"significant": {
"type": "integer",
"minimum": 1,
"maximum": 60,
"default": 30,
"description": "Significant digits for non-terminating results. Default 30."
},
"round_to": {
"type": "string",
"pattern": "^\\d*\\.?\\d+$",
"description": "Round to a multiple of this step, e.g. \"0.05\" for Swiss cash rounding."
},
"rounding": {
"type": "string",
"enum": [
"half_up",
"half_even",
"half_down",
"up",
"down",
"toward_zero",
"away_from_zero"
],
"description": "Rounding mode for decimals and round_to. Default half_up."
}
},
"examples": [
{
"operation": "payment",
"principal": "500000",
"annual_rate_percent": "1.8",
"years": 25
}
]
}