API · /towing-api

Towing Calculator API

healthy 3,655 Subscribers

Trailer-towing weight maths as an API, computed locally and deterministically. The tongue endpoint computes the tongue (hitch) weight as a percentage of the loaded trailer weight and reports the recommended 10–15 % range — too little tongue weight is the main cause of trailer sway. The capacity endpoint computes the maximum trailer weight a tow vehicle can pull, GCWR − curb weight − payload (the passengers and cargo in the vehicle), and checks a proposed trailer against it with the margin remaining. The payload endpoint computes the vehicle payload still available once the trailer is hitched, GVWR − curb weight − tongue weight, since the tongue weight presses down on the tow vehicle and counts against its payload rating. Everything is computed locally and deterministically, so it is instant and private. Ideal for RV, caravan, trailer and fleet apps, tow-vehicle matching and load-planning tools, and automotive calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. Guidance only — follow the manufacturer's ratings. 3 endpoints. This is trailer-towing weights; for tyre size and rolling circumference use a tyre API.

#towing #trailer #tongue-weight #automotive #rv #developer-tools

api.oanor.com/towing-api

Get an API key Try in playground → Contact provider

Machine-readable spec so AI agents can integrate this API.

/api/towing-api/openapi.json

/api/towing-api/llms.txt

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

Towing Calculator API — live data on the oanor API marketplace

API health

healthy

Uptime: 100.00%; Server probes · 24h
Avg latency: 86 ms; Server probes · 24h
Subscribers: 3,655; active
Total calls: 76; last 7 days

Full status page → · 12 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

3,000 calls / month
2 requests / second
Hard cap (429 above quota, no overage)
Tongue-weight % of loaded trailer weight
Single-trailer computations
Deterministic instant results
Community support

Starter

€9.00 /month

20,000 calls / month
5 requests / second
Hard cap (429 above quota, no overage)
Tongue-weight + gross-combined-weight maths
Hitch-load and payload-margin checks
Imperial and metric units
Email support

Pro

€24.00 /month

120,000 calls / month
15 requests / second
Hard cap (429 above quota, no overage)
Full towing-safety envelope calculations
Axle and weight-distribution outputs
Batch trailer configurations
Priority support + 99.9% uptime

Mega

€69.00 /month

600,000 calls / month
40 requests / second
Hard cap (429 above quota, no overage)
High-volume fleet and dealer integration
All endpoints, no per-call gating
Highest rate limits for bulk runs
Dedicated SLA and onboarding

Built by

PremiumApi

Related APIs

Other APIs with overlapping tags.

NHTSA Vehicle API

US vehicle data as an API, built on the official NHTSA datasets. Decode any VIN into make, model, year, trim, body class, engine, drivetrain, fuel type and assembly plant. Browse the full catalogue of vehicle makes and the models offered for any make and year. Then pull the safety record for a vehicle: open recalls with the affected component, the manufacturer summary, consequence and remedy; owner complaints flagging crashes, fires, injuries and deaths; and the official NCAP crash-test star ratings (overall, frontal, side and rollover). Real government data, no key needed upstream. Ideal for car marketplaces, dealer tools, VIN-lookup widgets, insurance and recall-check apps.

api.oanor.com/nhtsa-api

Turbocharger Boost API

Turbocharger and boost engineering maths as an API, computed locally and deterministically — the pressure-ratio, charge-air and airflow numbers a tuner, engine builder or motorsport engineer sizes forced induction with. The pressure-ratio endpoint gives the compressor pressure ratio = absolute manifold pressure ÷ ambient = (atmospheric + boost) ÷ atmospheric, so 10 psi at sea level is a 1.68 ratio — the x-axis of every compressor map, which climbs at altitude where ambient pressure is lower. The charge-air endpoint shows why an intercooler matters: compressing air heats it (T₂ = T₁ × (1 + (PR^0.2857 − 1)/efficiency)), and hot air is less dense, so the real gain is the charge density ratio = pressure ratio × (T₁/T_charge), not the pressure ratio alone — 10 psi at 70 % compressor efficiency makes ~93 °C and a 1.37 density ratio with no intercooler, rising toward 1.6 once an intercooler claws back the heat, and the estimated power gain tracks the density. The airflow endpoint gives the engine mass airflow ≈ displacement × (rpm/2) × volumetric efficiency × charge density, in lb/min — the y-axis of the compressor map you plot against the pressure ratio to land in the efficient island and avoid surge or choke. Everything is computed locally and deterministically, so it is instant and private. Ideal for engine-tuning and turbo-sizing tools, dyno and data-logging apps, and motorsport calculators. Pure local computation — no key, no third-party service, instant. Sizing estimates — verify on a dyno. 3 compute endpoints. For engine displacement and compression use an engine API; for shop compressed air a compressor API.

api.oanor.com/turbo-api

Air-Fuel Ratio API

Air-fuel ratio and lambda maths for engine tuning as an API, computed locally and deterministically — the lambda, AFR and mixture numbers a tuner, ECU developer or motorsport engineer dials fuelling in with. The lambda endpoint turns a measured air-fuel ratio into lambda (the AFR divided by the fuel's stoichiometric AFR — 14.7 for gasoline) and the equivalence ratio φ = 1/lambda, classifying the mix as rich, stoichiometric or lean: a gasoline AFR of 13.0 is lambda 0.88, an 11.6 % rich mixture, the sort used at wide-open throttle for power and a cooler, safer burn. The afr endpoint runs it the other way — pick a target lambda and it gives the AFR the wideband should read — and because the AFR number is fuel-specific (E85's stoichiometric AFR is about 9.8, not 14.7) it always works from the right fuel, which is why pros tune in lambda when switching fuels. The mixture endpoint links the air the engine breathes to the fuel the injectors must add: give an air mass and a target lambda and it returns the fuel mass (or vice-versa), the heart of how an ECU sizes fuelling from measured airflow. Built-in stoichiometric ratios for gasoline, E10, E85, ethanol, methanol, diesel, LPG, propane, methane/CNG and hydrogen, or pass your own. Everything is computed locally and deterministically, so it is instant and private. Ideal for engine-tuning and dyno tools, ECU and standalone-management apps, motorsport and data-logging utilities. Pure local computation — no key, no third-party service, instant. 3 compute endpoints. For engine displacement and power use an engine API; for chemical reaction stoichiometry a stoichiometry API.

api.oanor.com/airfuel-api

Quarter Mile Drag API

Quarter-mile drag-strip maths as an API, computed locally and deterministically — the classic empirical estimates a racer, tuner or car enthusiast uses to relate a car's power and weight to its performance. The et endpoint gives the predicted elapsed time and trap speed from flywheel horsepower and race weight using the standard formulas — ET = 5.825 × (weight ÷ hp) raised to the one-third, trap speed = 234 × (hp ÷ weight) raised to the one-third — so a 3,000 lb car with 300 hp is predicted to run about 12.6 seconds at 109 mph, assuming a competent launch and decent traction. The horsepower endpoint runs it in reverse: because trap speed is set by power-to-weight and barely by the launch, hp ≈ weight × (trap ÷ 234) cubed is a popular way to estimate flywheel power straight off a timeslip. The power-to-weight endpoint gives the ratio that actually decides acceleration — in horsepower per pound, horsepower per ton and watts per kilogram, the cleanest cross-unit figure — with a performance class from commuter through hot hatch and supercar to hypercar, because a light 200 hp car can beat a heavy 400 hp one. Everything is computed locally and deterministically, so it is instant and private. Ideal for drag-racing and tuner apps, car-spec and comparison tools, automotive enthusiasts and motorsport dashboards. Pure local computation — no key, no third-party service, instant. Empirical estimates assuming a good launch and traction — not a timeslip. 3 compute endpoints. For aerodynamic drag use a drag API; for gearing use a gear-ratio API.

api.oanor.com/quartermile-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Towing Calculator API?

Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Towing Calculator API with the x-oanor-key header. No credit card needed for the free tier.

What's the rate limit for Towing Calculator 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 Towing Calculator API cost?

Towing Calculator API has a free tier with 100 calls / month. Paid plans start at €9.00 / 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 Towing Calculator API GDPR-compliant?

All requests to Towing Calculator 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.

Towing 3

Meta 1

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

GET /v1/capacity

Towing capacity

Playground

Parameters

Custom headers

Language: Client:

GET /v1/payload

Vehicle payload

Playground

Parameters

Custom headers

Language: Client:

GET /v1/tongue

Tongue weight

Playground

Parameters

Custom headers

Language: Client:

GET /v1/meta

Spec

Playground

Custom headers

Language: Client:

Code snippets

curl https://api.oanor.com/towing-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."

const res = await fetch("https://api.oanor.com/towing-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();

$ch = curl_init("https://api.oanor.com/towing-api/SOME_PATH");
curl_setopt($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/towing-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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Towing Calculator API

API health

Pricing

Built by

Related APIs

NHTSA Vehicle API

Turbocharger Boost API

Air-Fuel Ratio API

Quarter Mile Drag API

Frequently asked questions

Parameters

Parameters

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Code snippets

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Discussion

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