Sodium Replacement
Calculator
Results
- Sodium loss per hour (mg)
- 1,140
- Total sodium to replace (mg)
- 3,990
- Equivalent table salt (g)
- 10.143061
- Total fluid loss (L)
- 4.2
Endurance training results
| Sodium loss per hour (mg) | 1,140 |
| Total sodium to replace (mg) | 3,990 |
| Equivalent table salt (g) | 10.143061 |
| Total fluid loss (L) | 4.2 |
formula-map diagram
- Sodium loss per hour (mg)
- 1,140
- Total sodium to replace (mg)
- 3,990
- Equivalent table salt (g)
- 10.143061
- Total fluid loss (L)
- 4.2
Formula breakdown
Formula
Na = sweat rate × [Na] × duration= 1140
Note
Simplified model: these are standard endurance-training formulas (Riegel, ACSM, Banister TRIMP, ACWR, Minetti gradient cost and published fuelling rates) applied to the numbers you enter. They assume even effort, typical conditions and average physiology, and ignore terrain, heat, wind, sleep, individual sweat and carbohydrate tolerance, and training history, so results are indicative planning figures, not medical or coaching advice.
More in Endurance training
See all →Frequently asked questions
How is my hourly sodium loss estimated?+
It's typically estimated from your sweat rate (volume of sweat lost per hour) multiplied by your sweat sodium concentration, which varies widely between individuals, commonly ranging from around 200 mg to over 2,000 mg of sodium per liter of sweat.
Why does sweat sodium concentration vary so much between people?+
Sodium concentration in sweat is largely genetically determined and also influenced by heat acclimatization, with well-acclimatized athletes often reabsorbing more sodium before it reaches the skin, resulting in lower sweat sodium concentration than an unacclimatized person in the same conditions.
What happens if I don't replace enough sodium during a long race?+
Inadequate sodium replacement combined with high fluid intake can contribute to hyponatremia, a dangerous drop in blood sodium concentration that causes confusion, nausea, and in severe cases can be life-threatening. This is more often caused by overdrinking plain water than by underreplacing sodium alone.
How can I find my actual sweat sodium concentration rather than using an average?+
Sweat testing services or patches can measure your individual sodium concentration directly, which gives a far more accurate basis for a replacement plan than population averages, since individual rates can differ by a factor of ten or more.
Should sodium replacement match fluid intake exactly?+
Not necessarily on a strict per-liter basis; the goal is matching your actual sodium losses (from sweat rate times concentration) rather than pairing sodium intake mechanically to fluid volume, since overdrinking fluid relative to sodium intake is what drives dilutional hyponatremia.