How many grams is 1 tablespoon of natural yogurt?

1 tablespoon of natural yogurt (plain whole-milk yogurt) weighs

15g

That's 0.5oz. An Australian 20ml tablespoon holds 21g.

A level US or UK tablespoon (15ml). USDA doesn't measure a tablespoon of this, so this is a sixteenth of its cup weight.

Other amounts of natural yogurt

Where these numbers come from

USDA FoodData Central, SR Legacy, food 01116: “Yogurt, plain, whole milk, 8 grams protein per 8 ounce”. USDA lists these household measures for it:

1 container (6 oz) = 170g
1 container (8 oz) = 227g
0.5 container (4 oz) = 113g
1 cup (8 fl oz) = 245g

Fractions of a cup are the cup weight scaled down. The tablespoon figure is the cup weight divided by 16, since USDA doesn't list a tablespoon for this ingredient. The teaspoon is a third of the tablespoon. Metric-cup figures assume a 250ml cup, and Australian tablespoons hold 20ml. Weights under 10g are rounded to 0.1g, everything else to the nearest gram. Full source list.