Electrolyte Calculator
Calculate your personalized daily electrolyte needs for sodium, potassium, and magnesium. Adjust for activity level, diet type, and exercise duration — with a detailed breakdown and hydration insights, all for free.
What Are Electrolytes?
Electrolytes are minerals that carry an electrical charge when dissolved in body fluids. The key electrolytes are sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), chloride, and phosphate. They regulate fluid balance across cell membranes, enable nerve impulses, drive muscle contractions (including the heart), and maintain blood pH.
Sodium, potassium, and magnesium work together as a system: sodium drives fluid into cells, potassium drives it out, and magnesium activates hundreds of enzymes that depend on the balance between them. Exercise, heat, and low-carbohydrate diets all dramatically increase electrolyte loss — making personalized targets far more useful than generic recommendations.
How Does the Electrolyte Calculator Work?
The calculator starts with the Dietary Reference Intake (DRI) base targets by gender, then adds adjustments for activity level, diet type, and exercise duration:
Base targets (DRI, adults):
- Sodium: 1500–2300 mg/day
- Potassium: 2600 mg/day (female) or 3400 mg/day (male)
- Magnesium: 310–320 mg/day (female) or 400–420 mg/day (male)
Activity adjustments (for sweat losses):
- Light: +500 mg Na, +200 mg K
- Moderate: +1000 mg Na, +400 mg K
- Intense: +1750 mg Na, +600 mg K, +100 mg Mg
Diet adjustments:
- Keto / Low-carb: +1250 mg Na, +500 mg K, +200 mg Mg (due to increased urinary losses on low insulin)
Exercise adjustment (optional):
Additional sodium = exercise duration (hours) × 500 mg/hour
(based on 300–1000 mg sodium per hour during prolonged exercise)
The sweat sodium loss estimate uses the formula:
Sodium loss (mg/hr) = sweat rate (L/hr) × sweat sodium concentration (mmol/L) × 23
Typical sweat sodium concentration: ~50 mmol/L (range 10–90 mmol/L).
Typical sweat rate: 0.5–2.0 L/hour depending on intensity and heat.
Why Use This Electrolyte Calculator?
- Personalized targets: Adjusts for your gender, activity level, diet, and exercise duration.
- Sweat-loss estimate: Optional sweat rate input gives a precise sodium loss per hour.
- Three key electrolytes: Sodium, potassium, and magnesium targets in one place.
- Chart visualization: See your daily targets and how they compare.
- Unit flexibility: Enter body weight in kg or lbs.
- Free & Private: No registration, no data storage.
Understanding Your Electrolyte Status
- Balanced: Your targets are within typical healthy ranges for your profile.
- High Demand: Your activity level, diet, or exercise duration requires significantly higher electrolyte intake — ensure you're replacing them.
- Very High Demand: Extreme exercise or strict keto may push sodium needs above 4,000–5,000 mg/day. Monitor how you feel and consider electrolyte supplements.
Note: These targets are estimates for healthy adults. People with kidney disease, heart failure, or hypertension should follow clinically prescribed electrolyte limits. Certain medications (diuretics, ACE inhibitors, NSAIDs) significantly alter electrolyte handling and override these general estimates.
Food Sources of Electrolytes
- Sodium: Table salt, processed foods, cheese, olives, pickles, sports drinks.
- Potassium: Bananas, potatoes, sweet potatoes, spinach, avocado, beans, yogurt, oranges.
- Magnesium: Nuts, seeds, whole grains, leafy greens, dark chocolate, legumes.
❓ Electrolyte Calculator FAQ
What are electrolytes and why do they matter?
Electrolytes are minerals (sodium, potassium, magnesium, calcium, chloride, phosphate) that carry an electrical charge in body fluids. They regulate fluid balance, nerve signaling, muscle contractions (including the heart), and blood pH. Imbalances can cause cramps, fatigue, dizziness, and in severe cases, cardiac issues.
How much sodium do I need per day?
Sedentary adults need about 1500–2300 mg of sodium per day. Active individuals and heavy sweaters may need significantly more — especially during prolonged exercise in heat. This calculator adjusts your sodium target based on activity level, diet, and exercise duration.
How much potassium do I need per day?
The Adequate Intake (AI) for potassium is 2600 mg/day for adult women and 3400 mg/day for adult men. Potassium is lost through sweat, but in much smaller amounts than sodium — there is no hourly guideline for potassium during exercise.
How much magnesium do I need per day?
The RDA for magnesium is 310–320 mg/day for adult women and 400–420 mg/day for adult men. Intense exercise and low-carb diets may increase magnesium needs slightly.
Why do low-carb and keto diets increase electrolyte needs?
On a low-carb or ketogenic diet, insulin levels drop, which causes the kidneys to excrete more sodium and water. This also increases potassium and magnesium losses. The calculator adds +1250 mg sodium, +500 mg potassium, and +200 mg magnesium for keto/low-carb diets.
How much sodium do I lose through sweat?
Sweat sodium concentration varies widely (10–90 mmol/L), but averages around 50 mmol/L. Using the formula sodium loss (mg/hr) = sweat rate (L/hr) × 50 × 23, a person sweating 1 L/hour loses roughly 1,150 mg of sodium per hour. This calculator provides an optional sweat-loss estimate when you enter your sweat rate.
Do I need electrolyte supplements?
For most people exercising for an hour or less, water and a balanced diet are enough to replace electrolytes. Electrolyte supplements are most useful for endurance athletes, heavy sweaters, people training in hot conditions, and those on keto/low-carb diets.
Can I get too many electrolytes?
Yes. Excessive sodium can raise blood pressure, and too much supplemental potassium or magnesium can cause side effects — in rare cases, high potassium can lead to irregular heart rhythms. People with kidney disease should be especially cautious and follow medical advice.
What are the best food sources of electrolytes?
Sodium: table salt, cheese, olives, pickles, processed foods. Potassium: bananas, potatoes, spinach, avocado, beans, yogurt. Magnesium: nuts, seeds, whole grains, leafy greens, dark chocolate, legumes.
How does exercise affect electrolyte needs?
Prolonged exercise (especially in heat) increases sweat losses of sodium and, to a lesser extent, potassium and magnesium. The ACSM recommends 300–1000 mg sodium per hour during exercise lasting more than 60 minutes, depending on intensity and conditions. This calculator adds an exercise adjustment for sodium based on duration.
Is this calculator suitable for athletes?
Yes, but athletes with very high sweat rates or extreme training loads may need individualized assessment (e.g., sweat patch testing). The optional sweat rate input helps refine the sodium loss estimate. For clinical or performance-critical decisions, consult a sports dietitian.
Can I use this calculator if I'm pregnant?
This calculator is not designed for pregnant or breastfeeding women. Pregnancy and lactation change electrolyte and fluid requirements. Consult your healthcare provider for personalized guidance.
How do I convert measurements between metric and imperial?
This calculator automatically converts between metric and imperial units. Simply select your preferred unit system, enter your measurements, and the calculator handles the conversions for you.