Matt Jenkinson

In late 2025, I started planning a trek to the Thorong La Pass in Nepal. It's one of the highest trekking passes in the world at 5,416 metres, and I wanted to go into it properly prepared. As a physiotherapist I know what sustained physical stress does to a body, and I wanted numbers I could trust, not guesswork.

I'm going as part of an organised group trek in October 2026. I'm not leading it. I'm a participant, same as anyone else on the trip. But with my background in exercise physiology and load carriage, I started researching seriously and found that most of the preparation tools online were either too vague or built on oversimplified formulas.

So I built better ones.

The calculators on this site use the same research I used to plan my own preparation. The Pandolf equation for calorie burn. Naismith and Tobler models for time estimates. The EN/ISO standard for sleeping bag ratings. Real formulas, not rules of thumb.

Every calculator on HikeCalc uses validated, peer-reviewed formulas. Calorie burn is calculated using the Pandolf load-carriage equation, a model developed for the US military and widely used in exercise science research. Hiking time is estimated from a weighted blend of Naismith's Rule, Tobler's hiking function, and the Book Time method. Sleeping bag ratings follow the EN/ISO 23537 standard that bag manufacturers use worldwide. Pack weight thresholds are based on load carriage research looking at injury risk and fatigue onset.

Clinical physiotherapy is essentially applied biomechanics and exercise physiology. I spend my working days thinking about how the body responds to load, movement, and sustained exertion. That background shaped what variables each calculator includes and what the outputs actually flag. The pack weight calculator, for example, doesn't just give you a ratio. It tells you when you're approaching the load threshold where injury risk meaningfully increases on multi-day trips, because that's the clinically relevant number.

These tools are estimates, not guarantees. Individual variation is real. But they're built on the same science I'd use to advise a patient preparing for a demanding physical challenge, and that's a better starting point than most of what's out there.

The Annapurna Circuit with a crossing of the Thorong La Pass is a serious undertaking. The pass sits at 5,416 metres. At that altitude you're working with roughly half the oxygen available at sea level. The circuit typically takes 12–21 days, with the pass crossing coming after a week of progressive altitude acclimatisation. The physical demands are significant: sustained daily distance, cumulative elevation gain, heavy-ish pack, and cold overnight temperatures above 4,000 metres.

I'll be honest, I'm not an experienced hiker. I've done plenty of day walks around New Zealand but nothing at this scale or altitude. The physiotherapy knowledge transfers directly in terms of understanding load and recovery, but the trail experience is something I'm building. I'm joining the organised group trek in October 2026, and I'm using HikeCalc's own tools to plan the preparation: tracking pack weight, estimating daily calorie needs for altitude days, and checking sleeping bag ratings for teahouse temperatures. If the tools hold up for Thorong La, they'll hold up for most things.

More calculators, more guides, and eventually a full write-up of the Nepal trek preparation process as real-world content. The plan is to document what I actually used, what the numbers predicted, and how accurate they turned out to be when I'm on the trail. That kind of honest field testing is more useful than another generic guide.