Hydration planning isn't one-size-fits-all. Environmental conditions, workout intensity, and personal biology all influence the fluid and electrolytes an athlete needs before, during, and after training.
The five Calculators in the Nix Solo app are designed to help athletes make informed hydration decisions using their own sweat and environmental data collected through Nix workouts. Together, these tools create a complete hydration workflow that can help athletes prepare for future conditions, optimize hydration intake leading into a session, personalize beverage choices, and recover more effectively afterward.
Below is an overview of the five Calculators available in the app, the order in which they are typically used, and how each one contributes to a personalized hydration strategy.
Prepare for future races and events using historic environmental conditions.
The Race Day Calculator is designed for athletes planning ahead for an upcoming race or training session that is more than 10 days away. Because accurate weather conditions are not yet available that far in advance, the Calculator uses 10 years of historic weather data to estimate the expected Nix Index environmental conditions for your session.
The app then uses your previous workouts completed in similar environments to identify hydration needs based on your own historical sweat data.
For any race or training session that is more than 10 days out.
The Race Day Calculator works best when you have completed multiple outdoor workouts across a variety of environmental conditions. You must have at least one workout logged above and below the predicted Nix Index for the given date. The more training data available, the more personalized the predictions become.
Once your event is within 10 days, transition to the Predictive Calculator for forecast-based recommendations.
Forecast hydration needs using upcoming weather conditions.
The Predictive Calculator is intended for workouts occurring within the next 10 days. Instead of relying on historic weather trends, this Calculator uses the upcoming weather forecast to estimate expected environmental conditions and projected Nix Index values.
The app then compares the forecasted conditions to your previous workouts completed in similar environments to predict your fluid and electrolyte losses.
Within 10 days of a race or key workout.
Similar to the Race Day Calculator, the Predictive Calculator works best when you have completed a variety of outdoor workouts across multiple environments. You must have at least one workout logged above and one logged below the predicted Nix Index for the given date in order to utilize the calculator. This calculator is especially useful when the weather changes before an upcoming session and you need to shift your hydration strategy based on the updated conditions.
Athletes should revisit the Calculator as the forecast continues to update closer to their event.
Hydrate effectively in the hours before training or competition.
The Priming Calculator helps athletes determine how to hydrate leading up to a workout or race.
Using your body weight, projected environmental conditions, and historical Nix workout data, the Priming Calculator estimates how much fluid and electrolytes you should consume before exercise begins.
The goal is to help athletes start sessions properly hydrated without over-consuming fluid or electrolytes.
1–2 days before or the morning of an important workout or race.
The Priming Calculator is based on hydration guidance recommending fluid intake in the hours prior to exercise. Recommendations are personalized using your Nix sweat profile and expected environmental conditions.
This Calculator is designed to complement your in-workout hydration strategy.
Build personalized hydration beverages around your sweat composition.
The Custom Drink Calculator helps athletes tailor hydration beverages to match their individual sweat composition. Because electrolyte concentrations vary significantly between athletes, beverage formulations that work for one person may not adequately support another.
Using your personalized sweat composition data, the Calculator allows you to compare drink formulations and determine how much of a selected formula is needed to support your hydration goals.
Athletes can choose to match their sweat composition based on sodium only or all electrolytes.
When you want to prepare your hydration strategy based on the electrolyte mix you already use, instead of receiving a product recommendation output using a formula you may not consume or have on hand.
Sweat composition is highly individualized. Some athletes lose substantially more sodium and electrolytes per ounce of sweat than others. The Custom Drink Calculator helps translate your sweat composition into practical hydration decisions using the products you already use in training and racing.
Rehydrate after training using your sweat loss data from the given workout
The Recovery Calculator is designed to be used immediately after a Nix workout in order to rehydrate and maximize recovery. Rather than estimating hydration needs from projected conditions, this Calculator uses your actual workout data to determine how much fluid and electrolytes should be replenished in the 1-2 hours following a workout.
Immediately after completing a Nix workout.
The Recovery Calculator takes into account the replenishments logged during the workout and then recommends a recovery strategy based on replacing 150% of the fluid deficit and 100% of the electrolyte deficit following your workout.
This is especially important for athletes training frequently or completing multiple sessions in a short period of time.