API · /psychrometric-api

Psychrometric Air API

healthy 4,556 Subscribers

Moist-air (psychrometric) thermodynamics as an API, computed locally and deterministically. The dewpoint endpoint computes the dew-point temperature and the saturation and actual water-vapour pressures from a dry-bulb temperature and relative humidity, using the Magnus-Tetens relation over water, es = 6.112·exp(17.62·T/(243.12+T)) hPa — the dew point is the temperature to which air must cool for water vapour to start condensing. The humidity-ratio endpoint computes the humidity ratio (mixing ratio) W = 0.621945·Pw/(P−Pw), the specific and absolute humidity, the vapour pressure and the moist-air enthalpy h = 1.006·T + W·(2501 + 1.86·T) kJ per kg of dry air, at any total pressure (default sea-level 101325 Pa). The wet-bulb endpoint computes the wet-bulb temperature with the Stull (2011) empirical fit and the wet-bulb depression, the gap between dry- and wet-bulb that widens as the air gets drier. Temperatures are in °C, relative humidity in %, pressures in Pa. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC, building-physics, meteorology, drying, greenhouse and data-centre-cooling app developers, comfort and condensation-risk tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is moist-air psychrometrics; for ASHRAE ventilation airflow use a ventilation API, for the WBGT heat-stress index a WBGT API and for the standard atmosphere an atmosphere API.

api.oanor.com/psychrometric-api
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Machine-readable spec so AI agents can integrate this API.

/api/psychrometric-api/openapi.json
/api/psychrometric-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
85 ms
Server probes · 24h
Subscribers
4,556
active
Total calls
20
last 7 days
status Full status page → · 24 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,500 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 2,500 calls/month
  • 2 req/sec
  • Dew point + humidity ratio + wet-bulb
  • No credit card
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Starter

€10.00 /month

  • 45,000 calls / month
  • 6 requests / second
  • Hard cap (429 above quota, no overage)
  • 45,000 calls/month
  • 6 req/sec
  • Enthalpy, absolute & specific humidity
  • Email support
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Pro

€26.00 /month

  • 280,000 calls / month
  • 15 requests / second
  • Hard cap (429 above quota, no overage)
  • 280,000 calls/month
  • 15 req/sec
  • HVAC & building-physics pipelines
  • Priority support
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Mega

€79.00 /month

  • 1,700,000 calls / month
  • 40 requests / second
  • Hard cap (429 above quota, no overage)
  • 1,700,000 calls/month
  • 40 req/sec
  • Platform scale
  • Dedicated SLA
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Built by

Related APIs

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Weather Calculator API

Meteorological formulas as an API — the derived weather figures, computed from your own readings, with no data feed or key needed. The wind-chill endpoint gives the "feels like" cold using the Environment Canada formula in metric (°C, km/h) or the US NWS formula in imperial (°F, mph), and flags when the reading is outside the valid range. The heat-index endpoint gives the apparent temperature from heat and humidity using the NWS Rothfusz regression with the standard low- and high-humidity adjustments. The dew-point endpoint uses the Magnus formula to turn temperature and relative humidity into the dew point, and also returns the vapour pressure and the absolute humidity. The beaufort endpoint maps a wind speed (m/s, km/h, mph or knots) to its Beaufort force and description, or a force back to its speed range. Everything is computed locally and deterministically, so it is instant and private. Ideal for weather apps and dashboards, agriculture and HVAC, marine and aviation, and outdoor and safety tools. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. This computes weather formulas from your own readings; for live forecasts and observations use a weather data API.

api.oanor.com/weathercalc-api

Propane & LPG Tank API

Propane and LPG tank maths as an API, computed locally and deterministically — the usable-fill, energy and burn-time numbers a homeowner, RV-er, grill-master or HVAC tech works out at the tank. The tank endpoint turns a tank size into real numbers: liquid propane is 4.24 lb per gallon and holds 91,452 BTU per gallon (about 21,569 BTU per pound), so a 20 lb barbecue cylinder carries roughly 4.7 gallons and 431,000 BTU. It knows the two ways tanks are sized — a portable cylinder (20, 30, 40 lb) is rated by the propane weight it holds, while a bulk tank (100, 250, 500, 1000 gal) is filled to only 80 % of its water capacity to leave room for expansion, so a 500-gallon tank actually holds 400 gallons of propane and about 36.6 million BTU. The burntime endpoint divides that energy by an appliance’s BTU-per-hour input rating to give run time: that same 20 lb cylinder runs a 30,000 BTU/hr patio heater about 14 hours, and an optional hours-per-day turns it into days. The refill endpoint costs a fill from a price per gallon, gives the cost per 100,000 BTU so you can compare propane to natural gas or electricity, and — with an appliance rating — the running cost per hour. Everything is computed locally and deterministically, so it is instant and private. Ideal for home-energy, HVAC, RV, off-grid, grilling and outdoor-living app developers, fuel-cost and tank-monitor tools, and propane-delivery calculators. Pure local computation — no key, no third-party service, instant. US units. Live, nothing stored. 3 compute endpoints. For vehicle fuel economy or the ideal gas law use a different API.

api.oanor.com/propane-api

Ventilation & Airflow API

Ventilation and airflow maths as an API, computed locally and deterministically. The air-changes endpoint relates the air changes per hour, the airflow in CFM and the room volume — ACH = CFM × 60 ÷ volume — and solves whichever you leave out (the volume can be given directly or as length × width × height), reporting the airflow in cubic metres per hour too. The required-cfm endpoint applies the ASHRAE 62.1 breathing-zone rule, outdoor airflow = people × Rp + floor area × Ra, with sensible office defaults (5 CFM per person and 0.06 CFM per square foot), to size the fresh-air a space needs. The duct-velocity endpoint computes the air velocity in a round or rectangular duct from the flow and the duct size, V = CFM ÷ area, in feet per minute, metres per second and miles per hour, with guidance on whether it is in the quiet residential or noisier high-velocity range. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC, building-services, indoor-air-quality and facilities app developers, ventilation-sizing and duct-design tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is ventilation and airflow; for heating and cooling load sizing use an HVAC API.

api.oanor.com/ventilation-api

Degree Day API

Heating and cooling degree-day maths as an API, computed locally and deterministically. The daily endpoint computes the heating degree days, HDD = max(0, base − mean), and the cooling degree days, CDD = max(0, mean − base), for a single day from a base temperature and the daily mean — or the minimum and maximum, since the mean is taken as their average. The period endpoint sums the degree days over a list of daily temperatures (means or min/max pairs), returning the total HDD and CDD, the count of heating and cooling days and the average temperature — the standard way to characterise a heating or cooling season. The energy endpoint turns degree days into an energy estimate: the heat delivered is UA·DD·24/1000 kWh from the building heat-loss coefficient, the fuel or electricity input is that divided by the boiler efficiency (or a heat-pump COP), and — with an energy price — the cost. Everything is computed locally and deterministically, so it is instant and private. Ideal for building-energy, HVAC and facilities tools, heating-bill and fuel-budget estimation, weather-normalisation and energy-benchmarking apps, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is degree-day demand estimation; for U-value and heat-loss fabric calculations use a U-value API.

api.oanor.com/degreeday-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Psychrometric Air API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Psychrometric Air API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Psychrometric Air API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Psychrometric Air API cost?
Psychrometric Air API has a free tier with 100 calls / month. Paid plans start at €10.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Psychrometric Air API GDPR-compliant?
All requests to Psychrometric Air API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/psychrometric-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/psychrometric-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/psychrometric-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/psychrometric-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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