# Automotive Calculators

Car math for agents: tire size and speedometer error, gearing and RPM, trip fuel, EV efficiency, towing, depreciation, lease versus buy, engines and braking.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://automotive-calc.x402tookit.com/openapi.json
- x402 manifest: https://automotive-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://automotive-calc.x402tookit.com/catalog
- Health (free): https://automotive-calc.x402tookit.com/health
- Uptime (free): https://automotive-calc.x402tookit.com/uptime

## Endpoints (10)

### GET /acceleration-estimate — $0.02
Estimate quarter-mile time and trap speed from weight and horsepower (Hale), plus a power-limited lower bound for 0-60 mph.
Params: weightLb: number, horsepower: number, powerAt?: string, drivetrainLossPercent?: number
Example: https://automotive-calc.x402tookit.com/acceleration-estimate?weightLb=3200&horsepower=300&powerAt=crank

### GET /depreciation — $0.02
Vehicle value year by year by straight-line, declining-balance or your own yearly percentage drops, with total loss.
Params: price: number, years: integer, method: string, salvageValue?: number, ratePercent?: number, schedule?: string
Example: https://automotive-calc.x402tookit.com/depreciation?price=30000&years=5&method=schedule&schedule=20%2C15%2C15%2C12%2C10

### GET /engine-calc — $0.02
Engine displacement in cc, litres and cubic inches from bore, stroke and cylinders; compression ratio and mean piston speed.
Params: bore: number, stroke: number, cylinders: integer, unit?: string, clearanceVolumeCc?: number, rpm?: number
Example: https://automotive-calc.x402tookit.com/engine-calc?bore=86&stroke=86&cylinders=4&unit=mm&clearanceVolumeCc=49.9&rpm=6000

### GET /ev-efficiency — $0.02
EV efficiency in kWh per 100 miles, miles per kWh, Wh per km and MPGe, range from battery size, and cost versus a gas car.
Params: efficiency: number, unit: string, batteryKwh?: number, pricePerKwh?: number, gasMpg?: number, gasPricePerGallon?: number, annualMiles?: number
Example: https://automotive-calc.x402tookit.com/ev-efficiency?efficiency=28&unit=kwh_per_100mi&batteryKwh=75&pricePerKwh=0.16&gasMpg=30&gasPricePerGallon=3.5

### GET /fuel-trip-cost — $0.02
Trip fuel and cost for legs with different mileage (city, highway), tank range, refuel stops, cost per person and a second car.
Params: legs: string, pricePerUnit: number, units?: string, tankSize?: number, reservePercent?: number, people?: number, roundTrip?: boolean, altEconomy?: number
Example: https://automotive-calc.x402tookit.com/fuel-trip-cost?legs=city%3A40%3A24%3B+highway%3A260%3A33&pricePerUnit=3.5&tankSize=14&people=2&altEconomy=40

### GET /gear-rpm — $0.02
Engine RPM at a road speed (or speed at an RPM) from tire size, axle ratio and transmission gear ratios, with a table by gear.
Params: tire: string, axleRatio: number, speed?: number, speedUnit?: string, rpm?: number, gearRatio?: number, gears?: string
Example: https://automotive-calc.x402tookit.com/gear-rpm?tire=26&axleRatio=3.73&speed=60&gears=1%3A3.59%3B+2%3A2.19%3B+3%3A1.41%3B+4%3A1.00%3B+5%3A0.83

### GET /lease-vs-buy — $0.02
Lease versus buy over the lease term: lease payment from money factor and residual, loan payment, resale equity and net cost.
Params: price: number, termMonths: integer, residualPercent: number, moneyFactor?: number, leaseAprPercent?: number, loanAprPercent: number, downPayment?: number, leaseFees?: number, salesTaxPercentOnLeasePayment?: number, resalePercent?: number
Example: https://automotive-calc.x402tookit.com/lease-vs-buy?price=30000&termMonths=36&residualPercent=60&moneyFactor=0.0025&loanAprPercent=6&downPayment=0

### GET /stopping-distance — $0.02
Stopping distance from speed: reaction distance plus braking distance on dry, wet, snow or ice, with road grade.
Params: speed: number, unit?: string, reactionSeconds?: number, surface?: string, friction?: number, gradePercent?: number
Example: https://automotive-calc.x402tookit.com/stopping-distance?speed=60&unit=mph&reactionSeconds=1.5&surface=dry-asphalt

### GET /tire-compare — $0.02
Tire dimensions from size codes like 225/45R17, and speedometer and odometer error when you change to a different size.
Params: currentSize: string, newSize?: string, indicatedMph?: number
Example: https://automotive-calc.x402tookit.com/tire-compare?currentSize=225%2F45R17&newSize=245%2F45R17&indicatedMph=60

### GET /towing-payload — $0.02
Towing check in pounds: payload left after people, cargo and tongue weight, tow rating and combined weight limits.
Params: gvwr: number, curbWeight: number, trailerWeight: number, towRating: number, tonguePercent?: number, occupantsAndCargo?: number, gcwr?: number
Example: https://automotive-calc.x402tookit.com/towing-payload?gvwr=6800&curbWeight=4900&trailerWeight=6000&towRating=7500&tonguePercent=12&occupantsAndCargo=600&gcwr=13500

## Terms

Automotive calculators using standard formulas and your inputs, provided as is. Results are estimates: real tire size, gearing, towing, braking and performance depend on the specific vehicle, loading, road and conditions. Always follow the manufacturer's ratings and your local law; this is not engineering, safety, financial or legal advice.