What your gut can handle isn't fixed.

Most ultras that go wrong go wrong in the stomach, and most fueling plans have nothing to say about it. They take your distance and the forecast and hand you a number. They keep no record of what you actually took in, or how it sat on you. UltraFuel keeps that record, and it is what makes the plan yours.

Train what your gut can handle
Carb tolerance moves. It takes weeks and it takes work, and UltraFuel gives that work a shape: you set your starting point, you decide when to take the dose up, hold it, or back off, and every long run you log shows what your gut actually handled at that dose. The app never moves that number for you. It keeps the record you decide from.

Built from your runs
Your carb, fluid and sodium targets come from your own logged training, not from distance and conditions. Carbs per hour, sweat rate, sodium losses, what to carry, and what to take at every aid station. Population averages are only the starting point. The more long runs you log, the more the numbers are yours. Syncs with Strava and Health Connect, so runs from Garmin, COROS and other watches flow straight in.

Race day, and the people waiting at the aid station
An aid station planner and an offline crew tracker. Share the plan and your crew sees what to have ready at every stop: what, when, how much. Drop-bag lists, per-station products, a printable crew sheet. Send a link and it opens in any browser, with no app and no account, for 48 hours. Crew who have the app pair with one code and keep working with no signal, which is where most of the race is.

Built for ultramarathon and trail runners, 50k through 100 miles and past it.

Why this exists
I built UltraFuel because I had a stomach I couldn't trust that had already cost me races, and a wife about to crew her first hundred with no idea what I'd need. One tool for both gaps. Every target here comes from your own logged training. The method is research-backed and refined with AI. It is not clinical advice, and it is not a replacement for your doctor or dietitian.
CJ, UltraFuel

Getting started
Free for good: your fueling profile, Gut Training, the Training Log, syncing from Strava and Health Connect (which covers Garmin, COROS and other watches), and one full race: aid-station and drop-bag planning, a printable crew sheet, and joining someone else's race as crew. Race Kit adds unlimited races, inviting your own crew with live tracking, a race-week carry plan with arrival projections, and the deeper analysis layer, at $11.99 a month or $69.99 a year with a 14-day free trial.

Delete the spreadsheet.