Bottle Calculator – ANDREWGRABBS

Calculate carb/electrolyte ratios and osmolarity for your custom sports drink.

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Total Carbs 0 g

Total Electrolytes 0 mg

Total Weight 0 g

Osmolarity 0 mOsm/L

Rating: Hypotonic

Maltodextrin:Fructose Ratio -

Understanding Your Ingredients

Maltodextrin

A complex carbohydrate that provides steady, long-lasting energy. It has a high molecular weight, which means it contributes less to osmolarity while delivering significant calories. Ideal for sustained endurance efforts.

Running low? Get quality maltodextrin

Fructose

A simple sugar absorbed through a different intestinal pathway than glucose (maltodextrin). Adding fructose allows you to absorb more total carbs per hour, but too much can cause GI distress. Best used in combination with maltodextrin.

Running low? Get pure crystalline fructose

Sodium

The primary electrolyte lost through sweat. Critical for fluid balance, nerve function, and muscle contractions. Most athletes need 200-500mg per hour depending on sweat rate and conditions.

Running low? Get sodium citrate

Potassium & Magnesium

Essential electrolytes for muscle function and preventing cramps. While lost in smaller amounts than sodium, they play crucial roles in cardiac function and muscle relaxation. Typical ratio: 2:1 potassium to magnesium.

Running low? Get potassium chloride Get magnesium malate

Caffeine

A central nervous system stimulant that can enhance endurance performance and reduce perceived exertion. Typical dose: 100-200mg consumed 30-60 minutes before exercise. Benefits include reduced fatigue, improved alertness, and enhanced fat oxidation. Individual tolerance varies widely - start with lower doses (50-100mg) if new to caffeine. Caution: May cause jitters, GI distress, or sleep disruption. Half-life is ~5 hours, so consider timing for evening workouts.

Running low? Get pure caffeine powder

Popular Ratios Used by Athletes

2:1 Maltodextrin:Fructose - The most researched and widely used ratio. Allows optimal carb absorption (up to 90-120g/hr) without overwhelming the gut.
1:1 Maltodextrin:Fructose - Higher fructose content for very high carb intake (120g+/hr) in ultra-endurance events. Requires gut training.
Glucose-only (Maltodextrin only) - Maximum absorption around 60g/hr. Good for shorter efforts under 2 hours where you don't need massive carb intake.

Note: The "right" ratio depends on your individual tolerance, effort duration, and training. Start conservative and experiment in training, never on race day!

The recommendations in this calculator are based on peer-reviewed scientific research:

Jeukendrup, A. E. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25-S33. DOI

Reviews evidence for multiple transportable carbohydrates (glucose + fructose) enabling 90-120g/hr carb oxidation vs 60g/hr for glucose alone, utilizing dual intestinal transporters SGLT1 and GLUT5.

Currell, K., & Jeukendrup, A. E. (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine & Science in Sports & Exercise, 40(2), 275-281. DOI

Demonstrated 8% performance improvement with 2:1 glucose:fructose ratio vs glucose-only drinks, with higher exogenous carbohydrate oxidation rates and reduced GI distress.

Maughan, R. J., & Leiper, J. B. (1999). Limitations to fluid replacement during exercise. Canadian Journal of Applied Physiology, 24(2), 173-187. DOI

Shows hypotonic solutions (250-270 mOsm/L) empty from stomach faster than hypertonic solutions (>350 mOsm/L) during exercise, improving fluid availability and reducing GI discomfort.

Baker, L. B., Dougherty, K. A., Chow, M., & Kenney, W. L. (2007). Progressive dehydration causes a progressive decline in basketball skill performance. Medicine & Science in Sports & Exercise, 39(7), 1114-1123. DOI

Documents sodium sweat losses of 20-80 mmol/L (460-1,840 mg/L) in athletes, supporting recommendations for 200-500mg sodium per hour based on individual sweat rate.

Vist, G. E., & Maughan, R. J. (1995). The effect of osmolality and carbohydrate content on the rate of gastric emptying of liquids in man. The Journal of Physiology, 486(2), 523-531. DOI

Demonstrates that gastric emptying rate is primarily influenced by solution osmolality; maltodextrin solutions empty faster than glucose solutions of equal carbohydrate content due to lower osmolality.

Jentjens, R. L., Moseley, L., Waring, R. H., Harding, L. K., & Jeukendrup, A. E. (2004). Oxidation of combined ingestion of glucose and fructose during exercise. Journal of Applied Physiology, 96(4), 1277-1284. DOI

Used stable isotope tracers to show glucose+fructose ingestion resulted in 55% higher exogenous carbohydrate oxidation (1.26 g/min) compared to glucose alone (0.81 g/min).

Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American College of Sports Medicine position stand: Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377-390. DOI

ACSM position stand providing evidence-based guidelines for fluid and electrolyte replacement during exercise, including sodium intake recommendations of 0.5-0.7 g/L for prolonged exercise.

All citations are from peer-reviewed journals. Individual responses may vary - consult with a sports dietitian or physician before making significant changes to your nutrition plan.

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