Outsmart
mile 20.
The wall is a fueling error. Fueling errors are computable.
Generic race advice hands every runner the same instruction: a gel every 45 minutes. That instruction ignores the three variables that decide whether fuel works: how much your gut can absorb, how much sodium you sweat out, and what the course does to your pace.
GI distress is the most common reason runners abandon a fueling plan mid-race, and an abandoned plan usually ends at the wall. CarbRate computes a plan your body can hold, and every formula in it is validated against published research before it ships.
Your plan lives on the actual course.
CarbRate places every fuel event on the race you're running: at water stations that exist, spaced for your gut, and never mid-climb, where your stomach has the least blood flow to spare.
Boston's caffeine gel goes in before the Newton hills. Chicago's plan knows all 20 aid stations. As of July 2026, no other fueling app pairs live in-run guidance with the real course profile.
Plan. Practice. Race.
A plan on paper doesn't finish a marathon. CarbRate builds the plan, trains your body to hold it, then runs it with you.
Stand in the corral already knowing
Answer a few questions about your race, your goal time, your sweat, and your gut. CarbRate hands back the exact schedule: what to carry, what the course hands you, and the mile each feed goes in.
Every fueling decision is made before the gun. Race day stops being a chemistry experiment and becomes a checklist you've already read.
Your stomach has done this before
The gut is trainable: practiced consistently, carb absorption climbs toward the 90 g/hr ceiling. CarbRate turns that research into one assignment per long run, so your race plan gets rehearsed piece by piece across the build-up.
By race week, the plan you're holding is one your stomach has already executed. More absorbed carbs is more fuel to the working muscles late, which is exactly where the wall lives.
At mile 17, thinking is expensive
Late in a marathon, arithmetic is the first thing to go. CarbRate does it for you, out loud: "gel at the station in 0.4 miles · tables on the right." You run. It counts.
And when the day changes — heat, a missed feed, a slower back half — Plan B recomputes the rest of the race on the spot. One dropped gel stays one dropped gel instead of becoming mile-22 damage control.
The fuel science is free on the web.
No download needed for the database. Every product verified against manufacturer data, scored on the science, and searchable right here.
Pay for the race, or the year.
- Your full schedule: every feed, placed on your race's real water stations
- Live race-day guidance with Plan B re-planning when the day changes
- Unlimited sweat tests and the full fueling course and gut-training program
Checkout opens in your browser · Apple Pay supported · your free plan preview stays free either way