Field-Tested • 35 Tools • No Login
Trailhead Lab is a small workshop of niche outdoor calculators. Each one tackles a specific backcountry decision — from how much water to carry in Death Valley to when the next lightning strike is too close.
Most online "hiking calculators" answer the same five things: pace, calorie burn, sunset time, distance conversion, and basic BMI. They're useful once. After that, real trip planning surfaces messier questions — how much water do I really need at 4,000 m in 30 °C? Will my tent hold 15 cm of fresh snow? Is that thunderstorm 8 km away or 4?
Trailhead Lab was built to handle those second-order questions. Every tool here was chosen because a guidebook, blog post, or generic converter ignores it. We've tried to publish the formulas we use (with citations where they exist) so you can audit a result before trusting it on a real trip.
Nothing here is medical, legal, or SAR-coordination advice. Treat outputs as starting points, and read the "Limitations" section on every tool page — there is no substitute for local conditions and trained judgement.
Eight categories, 35 calculators. Click any card to open it.
A composite difficulty rating that combines distance, elevation, terrain roughness, and surface — beyond the simple "Naismith + grade" most sites give you.
Estimates route time using Tobler's hiking function with grade, pack weight, and surface corrections.
Calculates liters per day for a given temperature, altitude, exertion, and humidity — and converts that into bottles per kilometer.
Paste ascent / descent data and get a difficulty profile, rest-stops suggestion, and "feel" rating.
Calculates optimal weight distribution, base weight target, and luxury-item trade-offs for your pack.
Estimates the environmental impact of a trip plan using group size, fragile-terrain flags, and length of stay.
Manufacturer ratings assume naked children. This adjusts for gear volume, season, and shoulder room.
Converts between EN/ISO Comfort, Limit, and Extreme ratings, and cross-references them with pad R-value.
A 0–100 score for a candidate campsite based on wind exposure, slope, drainage, hazards, and water proximity.
Estimates how much split wood you need for a given fire duration and intended use (cooking vs. warmth).
Calculates snow accumulation pressure on a fly and whether to shovel.
Combines bag rating + pad R-value + estimated overnight temperature to flag "this will be a cold night."
For multi-casualty backcountry incidents — ranks who needs attention first using a simple MARCH-based flow.
Estimates how long it takes to build several emergency shelter types based on materials and crew.
Compares liters-per-hour between boiling, filtering, UV, and chemical treatment for a given water source.
Estimates how long a search-and-rescue team is likely to take to reach a given last-known location.
Implements the 30/30 rule with thunder-speed correction, plus a visual risk dial.
Computes true bearing from magnetic bearing (and vice versa) for any year and location.
Predicts runtime for a handheld GPS given temperature, sample rate, and backlight use.
Estimates position error accumulation over a multi-leg route with no GPS — for when electronics fail.
Use the sun's hour-angle and declination to derive cardinal direction without a compass.
Calculates wet-bulb temperature — a more honest indicator of heat danger than heat index.
Implements the NWS (US) and apparent-temperature (AUS) formulas side-by-side.
Estimates cloud-base height from surface temperature and dew point — useful for ridge-walking decisions.
Reads barometer trend rules and outputs a forecast paragraph in plain English.
Combines sun, wind, humidity, and ground into a single exposure rating for clothing decisions.
Estimates calorie expenditure with MET + terrain + pack-weight + altitude adjustments.
Estimates sodium and potassium replacement per hour for hot-weather exertion.
Compares kcal-per-gram for trail foods and ranks them by calorie-per-gram efficiency.
Sums daily calorie target over a trip length, with macro defaults and gram-of-food outputs.
Estimates dawn/dusk activity windows for common mammals based on sunrise & sunset.
Rates a food-storage plan against local bear activity and regulations.
Combines flow, depth, temperature, and visibility into a "should we cross" verdict.
A natural placement slot reserved below the tools directory. Real ads fill this space once the site is approved.