Property intelligence

Rental Valuation API

Estimate the monthly rent for one home from ONS local authority rents and the bedrooms, property type and floor area on its latest EPC.

Endpoint

GET/api/v1/property/rental-valuation

Costs 1 credit. The estimate starts from the average rent for the bedroom count in the local authority, is scaled by the property type rent over the all-homes rent, then moves by up to 10% for floor area against a typical size for that bedroom count (50, 70, 90 and 125 m² for 1 to 4+ beds). Bedrooms are EPC habitable rooms minus one. Confidence is medium when bedrooms and type both come from the EPC, otherwise low, with a range of 15% or 25% either side. lhaRatePcm is filled when DWP names a BRMA after the local authority; otherwise use the LHA rates endpoint. No rent data for the area returns 404 and is not charged.

Billing details in the response

Successful chargeable JSON responses include a top-level billing object. The endpoint examples on this page focus on the endpoint-specific data, so this repeated block may not be shown in every example.

"billing": {
  "mode": "prepaid",
  "creditsCharged": 1,
  "creditsRemaining": 1999,
  "creditsRefreshAt": "2026-08-14T09:30:00.000Z"
}

Field or header	Meaning
billing.creditsCharged X-Credits-Charged	Credits charged by this call. Failed and non-chargeable calls return `0` in the header.
billing.creditsRemaining X-Credits-Remaining	The credit balance after the call.
billing.creditsRefreshAt X-Credits-Refresh-At	The next monthly credit refresh as an ISO 8601 timestamp. Trial and non-renewing balances return `null` and omit the header.

All authenticated API-key calls expose the billing headers, including validation errors and zero-credit status or management requests. Only successful chargeable JSON responses add the billing object to the response body.

When credits run out

If your balance is lower than the cost of a request, the API returns HTTP 402 and charges nothing. The error includes the credits needed, your balance and a link to change plan.

{
  "statusCode": 402,
  "statusMessage": "Payment Required",
  "data": {
    "success": false,
    "error": {
      "code": "INSUFFICIENT_CREDITS",
      "message": "This request costs 35 API credits. Upgrade your plan or wait for your monthly refresh: https://propertyinsights.co.uk/billing",
      "required": 35,
      "available": 12,
      "upgradeUrl": "https://propertyinsights.co.uk/billing"
    }
  }
}

Parameters

Name	Required	Type	Description
postcode	Yes	string	Full UK postcode in England or Wales.
address	Yes	string	First line of the address, used to find the EPC.

Source and coverage

Source: ONS Price Index of Private Rents (monthly, by local authority), DWP Universal Credit Local Housing Allowance rates, and the latest domestic EPC
Coverage: England and Wales local authorities. Scotland and Northern Ireland return 404 because ONS does not publish rents by council area there

ONS publishes bedroom and property type averages separately, not combined, so this is a guide to market rent rather than a survey-grade figure. Check it against local listings before relying on it.

Example request

curl -X GET "https://propertyinsights.co.uk/api/v1/property/rental-valuation?postcode=ZZ1%201ZZ&address=12%20Sample%20Road" \
  -H "x-api-key: YOUR_API_KEY"

Example response

{
  "success": true,
  "data": {
    "rentPcm": 2030,
    "range": {
      "low": 1725,
      "high": 2335
    },
    "confidence": "medium",
    "method": "ONS average rent for the bedroom count in the local authority, scaled by the property type rent over the all-homes rent, with a floor area adjustment of up to 10%.",
    "steps": {
      "baseCategory": "3bed",
      "baseRentPcm": 1769,
      "typeCategory": "semi_detached",
      "typeRatio": 1.111,
      "floorAreaAdjustmentPct": 3.3,
      "typicalFloorAreaSqm": 90
    },
    "inputs": {
      "address": "12 Sample Road",
      "postcode": "ZZ1 1ZZ",
      "bedrooms": 3,
      "bedroomsSource": "EPC habitable rooms minus one",
      "propertyType": "House",
      "builtForm": "Semi-Detached",
      "floorAreaSqm": 96,
      "epcCertificateNumber": "0000-0000-0000-0000-0001"
    },
    "area": {
      "areaCode": "E06000023",
      "areaName": "Bristol, City of",
      "region": "South West",
      "period": "2026-09"
    },
    "lhaRatePcm": 1300,
    "lha": {
      "brmaName": "Bristol",
      "category": "3bed",
      "rateYear": "2026-27"
    },
    "warnings": []
  }
}

OpenAPI specification

Authentication, parameters, billing headers and response schemas are also published in the machine-readable OpenAPI documents in JSON and YAML.