What is the ratio for simple syrup?

1 part sugar to 1 part water; rich syrup is 2 : 1. For 500 ml of 1 : 1 syrup by weight you need about 307 g each of sugar and water.

How much sugar for 1 kg of fruit?

At the usual 1 : 1 ratio, 1 kg of sugar. At 1 : 0.8 it is 800 g.

About 0.6 ml per gram in a 1 : 1 syrup: 100 g of sugar in 100 g of water makes about 163 ml.

Add water equal to syrup weight × (Brix now ÷ Brix wanted − 1). 300 g of 50 °Bx syrup needs 300 g of water to become 25 °Bx.

Sugar and water for a syrup of a given strength, and sugar for a weight of fruit

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Works out the sugar for a weight of fruit, the sugar and water for a simple syrup, and the water or syrup needed to reach a sugar content.

On "Simple syrup", choose "Sugar : water" and whether parts are measured by "Weight" or "Volume (cups)".
Under "I know", enter "The amount I want" or "The sugar I have"; sugar, water, Brix and volume appear.
On "Fruit syrup", enter the "Prepared fruit" weight and the ratio to get the sugar and a rough jar size.
On "Dilute or sweeten", find the water that lowers a syrup's Brix, or the syrup that sweetens a drink.

Brix = sugar ÷ (sugar + water) × 100, by weight. 1 : 1 by weight is 50 °Bx; 2 : 1 is about 66.7 °Bx.
Volumes use the USDA sucrose density table at 20 °C. 1 : 1 by volume (198 g sugar per US cup) is about 46 °Bx.
The page gives no storage times. Less sugar than fruit may shorten how long a syrup keeps.

What is the ratio for simple syrup?: 1 part sugar to 1 part water; rich syrup is 2 : 1. For 500 ml of 1 : 1 syrup by weight you need about 307 g each of sugar and water.
How much sugar for 1 kg of fruit?: At the usual 1 : 1 ratio, 1 kg of sugar. At 1 : 0.8 it is 800 g.
How much does sugar add to the volume of a syrup?: About 0.6 ml per gram in a 1 : 1 syrup: 100 g of sugar in 100 g of water makes about 163 ml.
How do I dilute a syrup to a lower Brix?: Add water equal to syrup weight × (Brix now ÷ Brix wanted − 1). 300 g of 50 °Bx syrup needs 300 g of water to become 25 °Bx.