Free automotive tools and data

Automotive calculators & data, without the guesswork

Free tools for tire fitment, wheels, towing, performance, fuel costs and vehicle data. Every result shows the formula behind it.

Explore all calculators Check a car's complaint record

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All 22 tools

Tire Size Calculator

Diameter, sidewall, circumference and revs per mile from the three numbers on the sidewall.

225 / 45 / R17 634.3 mm Overall diameter 101.3 mm sidewall · 808 revs/mile
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Tire Size Comparison

Two sizes side by side, diameter change, ride height and what your speedometer will read.

Good fit +0.4% Diameter change 205/55R16 → 225/45R17
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Wheel Offset Calculator

How a new width and ET move the wheel: poke, inner clearance and backspacing.

+12.7 mm More poke -12.7 mm Inner clearance 8.0J ET35 → 9.0J ET35
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Towing Capacity

Factory ratings by vehicle and year, plus the real-world limit once people and cargo are aboard.

11,500 lbMax trailer
1,150 lbTongue weight
Class VHitch
Open lookup

Browse by category

Tires & Wheels

Tire size, comparison, wheel offset, bolt pattern and the reference charts.

9 tools

Performance

0-60 times, quarter mile, gear ratios and compression ratio.

4 tools

Towing

US tow ratings by vehicle, Australian ratings and caravan calculators.

4 tools

Ownership & Data

Fuel cost, MPG, depreciation, NHTSA complaints and research.

5 tools

Built differently

Real data. Real formulas. No nonsense.

GarageCalc is for people who want the number and the reason behind it. Every calculator shows its math, every dataset names its source, and nothing you type leaves your browser.

About GarageCalc

All tools

Tires & Wheels

Tires

Tire Size Calculator

Overall diameter, sidewall height, circumference and revs per mile for any metric tire size.

 Tires

Tire Size Comparison

Compare two tire sizes side by side, with ride height change and a speedometer error table.

 Wheels

Wheel Offset Calculator

See how a new wheel width and offset change poke, inner clearance and backspacing.

 Wheels

Bolt Pattern Calculator

Find your PCD from a simple lug measurement, with a chart of common patterns by vehicle.

 Tires

Tire Load Index Chart

How much weight each tire can carry, from index 60 to 130, with instant lookup.

 Tires

Tire Speed Rating Chart

Every rating letter in mph and km/h, ZR explained, and mixing rules.

 Tires

Tire Date Code Decoder

Enter the 4-digit DOT code and see exactly how old your tires are.

 Tires

Tire Size Chart

326 common sizes with overall diameter in inches and mm, plus the sizes that can replace each one.

 Wheels

Bolt Pattern Chart

Every common PCD with the vehicles that use it, inch equivalents and look-alike patterns that do not fit.

Performance

Performance

0-60 Times Database

Real-world acceleration times for popular cars, trucks and EVs in one sortable table.

 Performance

Quarter Mile Calculator

ET and trap speed from power and weight, or horsepower from a timeslip.

 Drivetrain

Gear Ratio Calculator

Engine RPM at any speed from gearing and tire diameter, plus ring and pinion math.

 Engine

Compression Ratio Calculator

Engine builder math: static CR from your exact specs, plus total displacement.

Towing

Towing

Towing Capacity

Tow ratings by vehicle and year, plus a real-world calculator from GCWR and curb weight.

 Towing AU

Towing Capacity Australia

Braked and unbraked ratings, GVM, GCM and ball limit for popular utes and 4WDs.

 Towing AU

Caravan Towing Calculator

Checks a car and caravan against all four Australian legal limits at once.

 Towing AU

Caravan Weight Calculator

Tare, ATM, water, gas and gear into payload, loaded mass and ball weight.

Ownership & Data

Trips

Fuel Cost Calculator

Trip and road trip gas cost from distance, fuel economy and price, with cost splitting.

 Trips

MPG Calculator

Your true fuel economy from a fill-up, with metric conversions and cost per mile.

 Money

Car Depreciation Calculator

What a car is worth at any age and what ownership really costs per month in lost value.

 Data

Car Complaint Checker

Any model's 2026 NHTSA complaint count, year-over-year change and top problem areas, from 49,801 filings.

 Data

Automotive Data Research

Original studies on public automotive data, with methodology and reusable datasets.

Check fitment before you buy

Most bad wheel and tire purchases come down to three numbers nobody checked: the overall diameter change, the offset change, and the bolt pattern. GarageCalc covers all three in under a minute. Start with the tire comparison to keep your diameter within the safe 3 percent envelope, run the offset calculator to see exactly where the new wheel will sit, and confirm the bolt pattern matches your hub.

Every tool works entirely in your browser, on desktop and mobile, and shows the formulas it uses. Planning a haul instead? Look up towing capacity by vehicle, price out the drive with the fuel cost calculator, or see what your car is really costing you with the depreciation calculator. Arguing about acceleration? Settle it with the 0-60 times database. Shopping used? Run the model through the Car Complaint Checker first.