Hummingbird Nectar Solution Calculator

The standard hummingbird nectar recipe is one part plain white sugar to four parts water by volume.
That is it.
No red dye, no honey, no organic raw sugar, no brown sugar, no powdered sugar, no agave or any other substitute.

water_cups = total_oz / 8 × 4 / 5 sugar_cups = total_oz / 8 × 1 / 5

For a 32 oz feeder: 4 cups total volume, so 3.2 cups of water and 0.8 cups of sugar.
Bring the water to a boil, dissolve the sugar completely, let it cool to room temperature, then fill the feeder.
Boiling is only there to dissolve the sugar and slow microbial growth in a batch that will sit unrefrigerated. It is not strictly required, since the sugar will dissolve in cold water with enough stirring.

Why 4:1.
Measured by volume, one part granulated sugar to four parts water works out near 17 to 18% sugar by mass, because a cup of sugar weighs a good deal less than a cup of water.
Flower nectar from the species hummingbirds favour runs a little richer than that, roughly 20 to 25%, so 4:1 is at the dilute end of natural. That is deliberate: it is easier to drink, easier to keep clean, and the birds top up at real flowers anyway.
Going the other way, 3:1 (three parts water to one of sugar) is a genuine cold-weather energy boost and worth using during a cold snap or late in the season when flowers are gone.
5:1 and weaker is the one to avoid. It underdelivers on calories, and the birds work out quickly that a flower pays better than your feeder. The dropdown offers it because people ask for it in hot weather, but a clean feeder refreshed more often beats a watered-down one.

Why no red dye.
The dye is unnecessary, because the red plastic of the feeder itself is what attracts hummingbirds.
Red food coloring may be carcinogenic to hummingbirds at the concentrations they consume relative to body weight, though this is a precautionary stance rather than a proven harm.
Either way, there is no upside.
Plain clear nectar is the right answer.

Why no honey or raw sugar.
Honey ferments rapidly and grows fungus that can cause fatal tongue infections in hummingbirds.
Raw and brown sugars contain iron and molasses, which hummingbirds cannot process well, and long-term use causes liver damage.
Powdered sugar contains cornstarch, which ferments and clogs the feeder.
Plain white granulated sugar is pure sucrose, exactly what flowers produce, and is the only safe choice.

Feeder maintenance.
Empty and clean the feeder every 3-4 days in mild weather, every 2 days when above 80°F.
Mold grows in nectar within days at warm temperatures and can sicken birds.
Wash with hot water and a bottle brush; use a 10% white vinegar solution if mold appears, never bleach.
Store unused nectar in the fridge for up to a week.