Why these ratios?

A combination of glucose and fructose appears to create better overall absorption and reduce gastric distress, but the science behind which ratio is best varies.

Both glucose and fructose are absorbed in the small intenstine, but use different transporters. Stacking both together allows you to absorb more total carbohydrates. That said, fructose has a more limited transport capacity and it's easier to feel full or bloated from consuming too much, which is why most ratios contain more glucose than fructose.

2:1
This has been the traditional mixture favored by brands like Skratch Labs, Tailwind, Precision Fuel & Hydration.

1:1
You can achieve this mixture from table sugar. Formula 369 is one of the few brands that markets their prodcut directly as 1:1.

1:0.8
This is most notably used by Maurten 320 due to a specific research study that tested this ratio. This is also used by SiS Beta Fuel, Strkr Mix60 and Carbs Fuel.

Why these ingredients?

These are common ingredients that can be bought in bulk, reducing the cost of nutrtion and allowing you to adjust flavor individually.

Sugar
The cheapest option is table sugar from your grocery store. It's a perfect 1:1 ratio, the downside is it can end up overly sweet and some people are unable to tolerate the taste.

Maltodextrin
Most brands use maltodextrin in their mixtures because it is nearly flavorless compared to sugar. You generally need to order this in bulk online from Amazon or a food supply company.

Dextrose
This has a slightly faster absorption rate than maltodextrin, but is noticeably sweeter. However, it can be found in most grocery stores.

Fructose
This derives from fruit naturally, it does have a sweet flavor but since it's half or less of the ratio when combined with maltodextrin the flavor can still end up neutral. This can be found in most grocery stores or ordered online in bulk.

What should my concentration be?

Solution concentration affects how quickly your body absorbs fluids and carbohydrates. The right concentration depends on your goals and conditions.

Hypotonic (0–6%)
Absorbed fastest, best for pure hydration. Ideal for hot conditions or when hydration is the priority over fueling. This results in lower carb delivery per volume, meaning you may want to supplement with bars and gels.

Isotonic (6–8%)
Matches blood osmolality, providing an optimal balance of hydration and fuel delivery. This is what most commercial sports drinks aim for.

Hypertonic (8–15%)
Slower absorption, can pull water into the gut. This is a higher carb delivery but may cause GI distress and reduce net hydration. Best for cooler conditions or when using separate water.

How much salt?

The primary electrolyte lost through sweat is sodium, chloride is also lost in roughly equal proportions. Potassium, magnesium, and calcium are also lost, but to a much lesser extent.

Sweat rate
Without proper testing, your sweat rate is a guess — salt stains on your jersey are not necessarily an indicator of having saltier sweat, and the salt content of your sweat may also vary based on conditions.

General guidelines
Most nutritionist guidelines recommend 500-1000mg per hour during endurance exercise. For lower intensity in mild conditions, 300-500mg and for hard efforts in heat or humidity, upwards of 1500mg per hour.

Some personal experiementation is helpful. Start at 500–700mg and look for signs you've had too few electrolytes, such as muscle cramps and headaches after exercise.

Testing your sweat rate
Companies like Gatorade and Nix sell patches that can be used at home to test your sweat rate. Wearing these during workouts and completing them under a variety of conditions can give you a better starting point. Sports labs and companies like Precision Hydration also offer sweat rate testing.