Precision Fuel & Hydration planner: what it does and the best alternatives

If you searched for a “Precision Fuel calculator”, you probably mean the Fuel & Hydration Planner from Precision Fuel & Hydration (PF&H). It is free, it runs in your web browser, and it turns a short quiz into carbohydrate, fluid and sodium targets per hour for one event. PF&H says it takes about 2 minutes and that more than 143,000 endurance athletes have used it.

We went through the planner ourselves in October 2026 to see exactly what it asks. Below is what it does, what it does well, where it stops, and how it compares with the free Hexis race calculator, the Saturday app, and Mavr. Mavr publishes this article, so we also say where the others are better.

What the PF&H planner asks you

The questions change a little by sport. For a running plan, this is what we saw, step by step:

• Sport: triathlon, running, cycling, swimrun or other.
• Have you chosen a race yet? If not, you pick a distance. For running that is 5 km up to 100 miles.
• Likely race conditions: cold (under 10°C), mild (10 to 18°C), hot (19 to 26°C) or very hot (over 26°C).
• How you will approach the race: just finish, work hard, or race at your limit.
• Your target finish time, on a slider.
• How sweaty you are, on a slider, or your real sweat rate if you have measured it.
• How salty your sweat is, on a slider, or your result if you have had a Sweat Test.
• How often you get muscle cramps.
• A bit about you: date of birth, weight and sex.

We stopped at the personal details step, so the description of the results below comes from PF&H’s own pages rather than a plan we saved.

What you get at the end

• How much carbohydrate, fluid and sodium to take in per hour for your event.
• A step-by-step guide to hitting those numbers on the day.
• Product suggestions, including which strength of PF&H electrolyte drink is likely to suit you.
• The option to book a free video call with the PF&H Athlete Support team to go through your plan.

PF&H is open that the planner is an estimate. Its help pages say only a Sweat Test can tell you exactly how much sodium you lose, and that you should refine the planner’s numbers in training. Sweat Tests are done at test centres, and PF&H says the price varies by location.

What the planner does well

• It is free and quick, and you do not need to download anything.
• It looks at sodium and fluid, not just carbs. Some simple calculators only give carbs.
• It covers a wide range of events, from a 5 km to 100-mile ultras, plus triathlon, cycling and swimrun.
• It lets you enter real sweat data if you have it, so it gets better as you learn more about yourself.
• A real person can go through the plan with you on the free video call.

Where it falls short

• It plans one event, not your training. Your Tuesday intervals and Sunday long run do not get their own targets.
• There is no app, so the plan does not follow your training. If the forecast or your goal changes, you fill in the quiz again.
• Without a Sweat Test or measured sweat rate, your fluid and sodium inputs are a guess on a slider.
• It is made by a company that sells drinks, gels and electrolytes, so product suggestions point to its own range. That does not make the numbers wrong, but keep it in mind.
• PF&H describes it as a plan for the event itself. Its pages do not say it plans carb-loading in the days before or recovery after.

PF&H planner alternatives compared

Hexis race-day calculator

Hexis has a free race-day fuelling calculator on its website. It walks you through about a dozen steps on you, your habits, the race, the weather, your targets and your sweat. The result includes total energy demand, hourly carbs, fluid and sodium, food ideas such as gels, bars and drink mix amounts, recovery targets for the first hour after, and a packing list. For triathlon it sets the bike and run carb rates separately, because most people tolerate less on the run. It is the closest free match to the PF&H planner, and for triathletes it gives more detail.

Saturday

Saturday is an app that gives carbs, fluid and sodium per hour for each workout and race, based on how you sweat, the weather and the products you use. It can scan products with your camera and also gives do-it-yourself drink recipes with sugar, salt and water. It syncs workouts from TrainingPeaks and Intervals.icu. At $5.99 a month or $49.99 a year in the US App Store, it is the cheapest way to get the PF&H style of advice for every session, not just race day. It focuses on workouts and races rather than your daily meals.

Mavr

Mavr has free calculators on its website: a race plan calculator, a marathon fuel calculator with a gels, carbs and hydration plan, and a Hyrox calculator that plans fuel by station. These cover the same race-day job as the PF&H planner.

The Mavr app goes further than one race. It reads your training calendar from Runna, Strava, TrainingPeaks, Intervals.icu or Apple Health and sets carbs, protein, calories and hydration for every day. It times pre-, during- and post-workout fueling, gives fluid and sodium guidance that scales with heat, intensity and session length, and builds a race-day plan with carb-loading, race-morning meal timing and in-race carb and sodium targets. You can log meals by photo or voice and ask Kai, the AI coach, what to eat. It starts with a free trial with full access.

Where PF&H is better: it has a real sweat testing service and people you can talk to, and its sodium advice can be based on a lab test. Mavr is iPhone only and does not measure your sweat. If sodium is your main question, a Sweat Test plus the PF&H planner is hard to beat.

Check any calculator against the research

No calculator knows your gut. Use these research guidelines to check whether a number looks sensible, then test it in training before race day.

These numbers come from Asker Jeukendrup’s review in Sports Medicine. It also notes that carb advice during exercise does not depend on body weight, and that the targets may need to come down when the pace is easy. For fluid, PF&H suggests 500 to 1,000 ml per hour as a sensible starting range for events of 3 to 4 hours or more, and sodium from about 200 to 300 mg per hour for light sweat losses up to about 1,500 mg per hour for heavy, salty sweaters. You can measure your own sweat rate at home with a scale and a 1-hour run.

Verdict

The PF&H planner is a good free starting point for one race, especially if you care about sodium. Its limits are that it plans a single event, it has no app, and its sweat inputs are a guess unless you have test data. If you are a triathlete, try the Hexis calculator too. If you want the same kind of numbers for every workout, Saturday is the low-cost pick. If you want your whole training block fueled, from easy days to race morning, the Mavr app is built for that.

Frequently asked questions

Sources

1. 1The Fuel & Hydration PlannerPrecision Fuel & HydrationQuestions seen when stepping through the running path. Accessed October 2, 2026.
2. 2How to fuel and hydrate for an endurance racePrecision Fuel & HydrationAbout 2 minutes, 143,000+ athletes, carbs, fluid and sodium outputs, free video consultation. Accessed October 2, 2026.
3. 3Help Center and FAQsPrecision Fuel & HydrationPlanner is algorithm-based and recommends products; Sweat Test prices vary by centre. Accessed October 2, 2026.
4. 4How to nail your fuel and hydration strategy for endurancePrecision Fuel & HydrationFluid 500 to 1,000 ml per hour and sodium ranges for longer events.
5. 5Race Day Fuelling CalculatorHexisFree race-day plan with hourly carbs, fluid, sodium and a packing list. Accessed October 2, 2026.
6. 6Saturday: Pro Fuel & HydrationApple App Store (US)$5.99 a month or $49.99 a year; features. Accessed October 2, 2026.
7. 7A step towards personalized sports nutrition: carbohydrate intake during exerciseJeukendrup A, Sports Medicine, 2014Carbohydrate intake guidelines by exercise duration.