C to K Conversion Calculator

The C to K conversion calculator turns cups (C) into kilograms (K) — and back again — using the ingredient’s density. Instead of guessing whether 2 cups of flour is 0.24 kg or 0.5 kg, choose the ingredient from the list, enter the amount, and get a precise weight or volume in seconds.

This tool is built for anyone working with recipes, meal prep, or nutrition tracking. Because a cup of flour and a cup of honey do not weigh the same, the calculator includes common kitchen ingredients with typical grams-per-cup values, plus a custom density option for anything else you measure.

Use the conversion direction toggle to switch between cups to kilograms and kilograms to cups, and use the step-by-step breakdown to see exactly how the number was calculated.

🥄 Cups to Kilograms Converter

Convert between volume (cups) and weight (kilograms) for common kitchen ingredients.

Ingredient

Conversion direction

Amount (cups)

Enter an amount to see the conversion.

How the Cups-to-Kilos Conversion Works

In nutrition and recipe work, cups measure volume while kilograms measure mass. To move between them you need the ingredient's density — in this case, the number of grams that fits into one cup. Once you know that value, the conversion is simple arithmetic.

The conversion formulas
Grams = cups × grams per cup
Kilograms = cups × grams per cup ÷ 1000
Cups = kilograms × 1000 ÷ grams per cup

For example, water has a density of about 240 g per US cup, so 1 cup of water weighs 0.24 kg. All-purpose flour is about 120 g per cup, so 1 cup of flour weighs only 0.12 kg. The same volume can represent very different weights, which is why this calculator asks you to choose an ingredient or enter a custom density.

Step-by-Step Guide

Select the ingredient from the dropdown. If your ingredient is not listed, choose Custom density and type the grams per cup value.
Choose the conversion direction: cups to kilograms or kilograms to cups.
Enter the amount. The label changes automatically depending on the direction you picked.
Press Convert to see the weight or volume, plus a short calculation breakdown.
Use Reset to clear the form or Copy result to copy the output to your clipboard.

Worked Examples

Example 1: All-purpose flour. You need 2.5 cups of flour. Density = 120 g/cup. Mass = 2.5 × 120 = 300 g, which is 0.3 kg. The result shows 2.5 cups = 0.300 kg (300 g).

Example 2: Butter. A recipe calls for 1.5 cups of butter. Butter weighs 227 g per cup. Mass = 1.5 × 227 = 340.5 g = 0.341 kg.

Example 3: Reverse conversion. You have 1 kg of granulated sugar and need cups. Sugar density = 200 g/cup. Cups = 1000 ÷ 200 = 5 cups.

Reference Table: Common Ingredient Cup Weights

Densities vary with packing, sifting, humidity, and even brand. Use the table below as a starting point; the USDA FoodData Central database is a more authoritative source for specific products.

Ingredient	Grams per cup	Cups per kilogram
Water / milk	240	4.17
All-purpose flour	120	8.33
Whole wheat flour	125	8.00
Granulated sugar	200	5.00
Brown sugar (packed)	220	4.55
Butter	227	4.41
Rolled oats	90	11.11
Honey	340	2.94

Tips & Accuracy Notes

Use a kitchen scale for macro tracking. Cups are convenient for cooking, but grams and kilograms are far more accurate for calorie and macronutrient tracking. Weigh your ingredients whenever precision matters.

Packing changes everything. Brown sugar is usually packed into the cup, while flour should be spooned and leveled. A packed cup of brown sugar can weigh significantly more than a loosely filled cup. Always note how the recipe intends the ingredient to be measured.

The US legal cup is 240 mL; the metric cup is 250 mL. The difference can shift results by about 4%.
For custom ingredients, use a measuring cup to scoop the ingredient, then weigh it on a scale to find its true grams-per-cup value.
Liquid density changes with temperature, but for water, milk, and most cooking liquids the effect is tiny.

Frequently Asked Questions

What does C to K mean?
C stands for cups and K stands for kilograms or kilos. This calculator converts volume measurements in cups to weight measurements in kilograms, and the reverse direction as well.

Why doesn't 1 cup always weigh the same?
Because cups measure volume, and different ingredients pack differently. A cup of airy flour and a cup of dense honey contain very different amounts of matter. Converting volume to mass requires density.

How accurate is this calculator?
It is as accurate as the density value you use. The preset values are common averages, but real flours, grains, and packaged products can differ. For the best result, determine the density of your exact ingredient by weighing a level cup.

Can I convert any ingredient?
Yes — choose Custom density and enter the grams per cup for any ingredient. You can look up values in the USDA FoodData Central database or measure it yourself.

What if my recipe uses metric cups?
A metric cup is 250 mL, so 1 metric cup of water weighs about 250 g. Use custom density 250 for those recipes, or be aware that results will be roughly 4% higher than US cups. More details are available on Wikipedia's cup unit page.