Overlanding Calculators

Free tools for every build decision — from regearing to campsite power.

Every overlanding decision involves real engineering — gear ratio math after a tire upsize, winch line tension at angle, watt-hours for a fridge plus Starlink, ground clearance after a 2.5" lift. The 15 calculators below are the math, the formulas, and the verdict, with sources cited where it matters. No login, no paywall, Imperial or metric, mobile-first, and you can embed any of them on your own site.

Vehicle & Drivetrain

Gear Ratio Calculator
Find your ideal regear ratio after a tire size change.
Tire Size Comparison
Compare two tire sizes: diameter, width, speedometer error.
Caster Correction
Calculate CV angle and caster correction after a lift.
Ground Clearance
Estimate new ground clearance after lift and tire changes.
Payload Capacity
Check remaining payload after mods, passengers, and cargo.
Towing Capacity
GTW, tongue weight, and weight distribution for trailers.

Trail & Recovery

Airing Down PSI
Get ideal off-road tire pressure for sand, rock, mud, and trail.
Winch Line Pull
Calculate required winch force and check your winch rating.
Kinetic Rope Sizing
Find the right kinetic recovery rope for your vehicle weight.
Approach Angles
Calculate approach, departure, and breakover angles.
Fuel Range
Total range with main tank, aux tank, and jerry cans.

Camp & Systems

Battery Bank
Size your 12V battery bank, solar array, and DC-DC charger.
Water Supply
Calculate water needs for your crew and trip duration.
Altitude Cooking
Water boiling point and cooking time adjustments by altitude.
Roof Rack Weight
Check dynamic and static load ratings for your roof rack setup.

Why these calculators exist

Overlanding builds compound — a tire upsize changes effective gear ratio, available payload, ground clearance, fuel range, and even speedometer accuracy at the same time. Knowing the second-order effects before you spend $4,000 on lift kits and 37s saves rework, warranty headaches, and trail breakdowns far from cell service.

Each calculator returns three things: the number, a verdict in plain language (pass, warn, or fail with the threshold called out), and an editorial explainer covering the formula, common pitfalls, and the gear we recommend. Sources cited include SAE J689 for vehicle geometry, TRA load-index charts for tire ratings, U.S. Army FM 20-22 ground-resistance coefficients for winch force, and published overlanding consensus from Overland Expo and Jonathan Hanson’s field guides where math runs out and judgment takes over.