How do I know my sweat sodium concentration?

Commercial tests (like the GSSI Sweat Patch or Precision Hydration tests) measure sweat sodium directly. Without testing, 920 mg/L is a reasonable average, but salty sweaters (white salt stains on skin/clothes) should assume higher values.

What is the risk of insufficient sodium replacement?

Exercise-associated hyponatremia (low blood sodium) is a potentially life-threatening condition most common in slow endurance athletes who drink large amounts of plain water. Adequate sodium prevents dangerous dilution.

How should sodium replacement be timed?

For events over 2 hours, sodium replacement should begin in the first hour rather than when thirst or symptoms occur. A proactive salt intake strategy prevents larger deficits from developing.

Sodium Loss Per Hour Calculator

Calculate hourly sodium loss during exercise from sweat rate and individual sweat sodium concentration for personalized salt replacement in endurance events.

Use the full interactive calculator below, or

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Frequently Asked Questions

How do I know my sweat sodium concentration?

What is the risk of insufficient sodium replacement?

How should sodium replacement be timed?