The automotive toolbox
for mechanics & car owners
Free calculators, guided diagnostics, OBD-II codes and learning content — fast, mobile-first, installable as an app, and respectful of your privacy. No signup. Ever.
Dacia Logan 2021
Most used tools
Quick access to the calculators drivers and mechanics reach for most.
Interactive Car Diagnostic
Answer guided questions to narrow down why your car is behaving badly.
Open tool →Battery Calculator
Estimate battery health from open-circuit voltage and estimate runtime.
Open tool →Tire Calculator
Decode tire sizes and compare two sets with speedometer impact.
Open tool →Fuel Consumption Calculator
L/100 km, MPG, trip cost with fuel price and tolls.
Open tool →Garage Quote & Invoice Generator
Build professional estimates and invoices, then export as PDF.
Open tool →OBD-II Code Lookup
Search thousands of diagnostic trouble codes with causes and fixes.
Open tool →All 42 free tools
Diagnostics, electrical, engine, brakes & tires, fuel, transmission and garage tools — grouped by category.
Diagnostics
Interactive Car Diagnostic
Answer guided questions to narrow down why your car is behaving badly.
Air Conditioning Diagnostic
Step-by-step guide to find out why the AC is not cooling.
OBD-II Code Lookup
Search thousands of diagnostic trouble codes with causes and fixes.
OBD-II Live Scanner
Live RPM, speed, coolant and battery over Bluetooth with a BLE ELM327 adapter.
Photo Diagnostic Assistant
Photograph a tire, pad, disc or leak and follow an inspection checklist.
Sound Diagnostic Assistant
Record an engine noise and match it to likely causes.
Live OBD PID Data
Real-time engine data with charts — RPM, speed, coolant, MAF, load and battery analysis.
OBD Protocol Compatibility
Find which OBD protocol your vehicle uses — CAN, KWP2000, J1850 and more.
Electrical
Battery Calculator
Estimate battery health from open-circuit voltage and estimate runtime.
Charging System Check
Analyze alternator and charging voltage with the engine off, idling and loaded.
Engine
Oil Change Calculator
Oil quantity, service interval, filter and full service checklist.
Torque Specs Lookup
Search verified tightening torque values for common components.
Spark Plug Calculator
Replacement interval, cost and a quick misfire symptom assistant.
Cooling System & Coolant
Overheating diagnostic tree and coolant mix calculator.
Engine Compression Calculator
Theoretical compression ratio from bore, stroke and chamber volume.
Engine Builder Calculator
Displacement, piston speed and power estimates from bore and stroke.
Power & Torque Converter
Convert kW ↔ hp, Nm ↔ lb-ft and derive torque from power at RPM.
Oil Change Specs
Exact oil quantity, viscosity and filter for your car model and engine.
Brakes & Tires
Tire Calculator
Decode tire sizes and compare two sets with speedometer impact.
Wheel Diameter Calculator
Total diameter, circumference and distance per revolution.
Brake Calculator
Disc thickness, pad wear alerts and replacement cost estimate.
Fuel & Economy
Transmission
Garage & Billing
Garage Quote & Invoice Generator
Build professional estimates and invoices, then export as PDF.
Repair Cost Calculator
Real cost, margin and client price for any repair job.
Parts Margin Calculator
Set different margins for retail and professional customers.
Labor Cost Calculator
Time × hourly rate, plus parts and extras for the full bill.
Customer Manager
Client cards, linked vehicles and service history — stored only on your device.
Digital Service Book
VIN, mileage and full maintenance history per vehicle.
Service Reminders
Push notifications when an oil change or service comes due.
Vehicle Dashboard
A live status board per vehicle, computed from your service book.
Garage Dashboard
Revenue, accepted quotes, most profitable work and clients at a glance.
Parts Inventory
Track part stock with low-stock alerts and stock value.
Voice Assistant
“Create a quote for brake pads” — spoken commands become actions.
Photo → Quote
Photo of the car → confirm works → parts + labor → quote PDF.
Diagnostic Report Generator
Build a printable diagnostic report from a code or symptom with findings and checks.
Learn
Maintenance Checklist
Interactive 10,000 km service checklist you can tick on your phone.
Mechanic Quiz
Test your automotive knowledge and learn with explanations.
Which Tool Do I Need?
Pick an operation and get the exact tools, steps and safety warnings.
Mechanic Training
6 levels of interactive lessons and quizzes — from fundamentals to advanced.
AI Mechanic Assistant
13 free AI tools: mechanic chat, OBD explainer, photo inspection, voice commands, trip planning and more.
Car Programming & Tuning
ECU tuning, module coding, keys/immobilizer, gains calculator, coding logbook and tuning glossary.
Learn it in minutes
Practical guides with clear steps — from checking your oil to reading the check engine light.
How to Replace a Car Fuse: Easy Step-by-Step Guide
Most modern vehicles have at least two fuse boxes:
Read the guide →How to check your engine oil
Checking engine oil takes two minutes and can save your engine. Here is the correct way to do it.
Read the guide →How to change a car battery safely
Replacing a battery is one of the easiest DIY jobs — if you follow the right order and safety rules.
Read the guide →How to check brake pads at home
You can check brake pad wear in minutes without removing the wheels — here is how.
Read the guide →Understanding the check engine light
The check engine light means the car detected a fault. What to do depends on whether it is steady or flashing.
Read the guide →How to read a tire sidewall
Every number on the tire tells you something. Learn to read 205/55 R16 and the load and speed indexes.
Read the guide →Install AutoTools like an app
Open the menu in your browser and choose "Add to Home Screen". AutoTools then launches full-screen like a native app and several tools keep working offline.
Learn more