Calories in bread: a slice of white, whole wheat and rye

A 40 g slice of white bread has about 105 calories, and a thin 28 g sandwich slice about 75. Per 100 g, white bread has about 265 kcal and whole wheat 252, so the type of bread makes less difference than how many slices you eat and how thick they are.

When I started weighing what I eat, bread was the biggest surprise. Not because a slice has a lot of calories, but because I'd eat three or four with lunch without noticing. Below are the numbers I use, each with its source.

How many calories are in 100 g of bread?

White bread has about 265 kcal per 100 g in my table. Whole-wheat bread has 252 kcal, with 6 g of fibre against 2.5 g in white. "Wheat bread" in the US sense, made from a mix of white and whole-wheat flour, has 274 kcal. The whole-wheat and wheat values are USDA's.

These are reference values, not your bakery's label. Bread with seeds, milk or more oil has more. If the pack has a nutrition label, it beats any table.

How many calories are in a slice of bread?

A slice of bread has about 75 to 160 kcal, depending on its weight, because there is no standard slice. A slice I cut from a bakery loaf is usually 40 to 50 g; a thin slice from a packaged sandwich loaf can be under 30 g.

Bread	kcal / 100 g	Slice	kcal per slice
White, bakery loaf	265	40 g	105
White, thin slice	265	28 g	75
Whole wheat	252	32 g	80
Wheat (white + whole-wheat flour)	274	29 g	80
Rye		28 g (1 oz)	75
French or sourdough, toasted		28 g (1 oz)	90
Lepinja (Balkan flatbread)	270	150 g, whole	405

Source: my food table for white bread and lepinja; USDA for the rest (household-measure list, FoodData Central 172688 and 172686). Rounded. If you cut thicker, use your own weight: a 60 g slice of white bread is about 160 kcal.

Does whole wheat bread have fewer calories than white?

Whole wheat bread has barely fewer calories than white: 13 kcal per 100 g less, about 5 kcal per 40 g slice. Whole wheat (wholemeal in the UK) has more than twice the fibre, so it keeps me full for longer, and that's the real reason I choose it. But "whole wheat" on the label isn't a licence for a double portion.

Watch the names too. "Brown" or "dark" bread isn't automatically whole wheat or rye; the colour can come from malt or caramel. If it matters to you, read the ingredients and look for whole-wheat or wholemeal flour at the top of the list.

How many calories are in sourdough bread?

Toasted sourdough has about 90 kcal per ounce (28 g) in USDA's data, which groups it with French and Vienna bread; my table has no sourdough row yet. A fresh slice has more water, so it carries a little less per gram. Sourdough loaves differ a lot in size and flour, so for a bought loaf the label or the bakery's numbers are the best source.

Does toasting bread reduce the calories?

Toasting bread doesn't reduce its calories; it only drives off water, so the slice weighs less. You can see it in USDA's own numbers: toasted white bread is about 80 kcal per ounce, about 290 per 100 g, against about 265 for fresh, because the same calories now sit in fewer grams. So I weigh bread before toasting or simply count slices.

The same goes for crispbread and rusks: per 100 g they have more than fresh bread because they're dry. One is light; it's just easy to eat five.

How much bread can I eat when I'm losing weight?

There's no ban on bread when you're losing weight: on an 1,800-calorie day, two 40 g slices with lunch are about 210 kcal, which is perfectly normal. The trouble starts when bread comes with everything: breakfast, lunch and dinner, two or three slices each time. That's seven to nine slices, about 740 to 955 kcal, and none of it was the main dish.

Spreads add up too. Two 40 g slices with 10 g of butter are about 285 kcal, and a thicker spread by eye adds more.

What works for me:

• Bread goes on my plate, not in a basket in the middle of the table. That way I know how much I took.
• With dishes that already have carbs (beans, potatoes, pasta) I skip bread or take one slice.
• I weighed my usual slice once. Now I know "my slice" is 50 g and I don't guess.

How do I weigh my slice?

To weigh a slice of bread, put a plate on a kitchen scale, zero it and add the slice. Write down the grams and multiply by the kcal per 100 g from the table above, divided by 100. Do it once for the bread you buy most often, and after that just count slices.

Without a scale, I log my best guess and mark it as an estimate. Small things like this are why I'm building Calorko, an Android app that knows everyday breads, including the Balkan ones, and their usual portions.

In short

• White bread: about 265 kcal per 100 g; a 40 g slice about 105, a thin 28 g slice about 75.
• Whole wheat (252) and wheat bread (274) are close to white; whole wheat has more fibre.
• Toasting doesn't remove calories, only water.
• The amount matters more than the type: weigh your slice once and you'll know it for good.