KetoCalculator: A web-based calculator for the ketogenic diet


Address correspondence to Beth Zupec-Kania, R.D., C.D., Consutant, 1325 Victoria Circle S., Elm Grove, WI 53122, U.S.A. E-mail:


The classic ketogenic diet (KD) is a mathematically calculated diet with specific daily goals of fat, protein, and carbohydrate. Precise quantities of foods are then derived from these values which result in meal plans for the individual patient. The algebraic algorithm to determine a single meal requires approximately 35 calculations. This process is time consuming given that each individual requires many meals for variety and satisfaction. Computer applications can process multiple calculations in seconds. In 1997, a program was designed by this author with LifeTime Computing, a computer software company. This program was rebuilt into digital format in 2002, given the title KetoCalculator, and made available to registered dietitians on the World Wide Web (Zupec-Kania, 2002).

KetoCalculator (KC) is a tool for calculating multiple components of the ketogenic diet (KD) including meals, formulas, nutrition supplements, fluids and the carbohydrate content of medications. The program also functions as a database to store and archive calculations for future reference. The advantage of using a web-based program over software products is that changes can be made in the master database and are available to the user instantly; periodic updates are not required. The master database is regularly updated with current food and product data.

Program Steps

The program is designed to simulate the manual calculation of the diet and is organized in a step-by-step fashion. Initial entry of demographic data includes the name, date of birth, desired weight for length, and gender of the individual to facilitate creation of the diet.

The first calculation step in the KC is the estimation of energy requirements. The recommended dietary allowances (RDA) (Food and Nutrition Board, 1989) may be used as a baseline value from which 80–90% is calculated. The KC program automatically computes a guiding range of 75–85% of the RDA allowing an additional 5–10% of calories set aside for ketogenic snacks. Clinical judgment is required to determine the final calorie goal. This determination considers the individual's activity level, weight, and previous energy intake. Additional calories for a ketogenic snack may be created later in a separate feature of the program.

The second step is determination of the individual's protein requirement; this is automatically calculated from established RDA tables using the previously entered weight and age.

The third step is determination of the ketogenic ratio, which is the relationship between grams of fat to the combined grams of protein and carbohydrate. In a 4:1 ratio, there are 4 g of fat for every gram of protein and carbohydrate combined. The ratio impacts the degree of ketosis and can be manipulated during therapy to alter ketosis. Historically, a 4:1 ratio is prescribed for young children. Lower ratios such as 3:1 may be used for older children to allow for higher protein needs. More liberal ratios could be prescribed such as 2:1 or 1:1 for individuals who are overly ketotic or unable to consume the high-fat content of the higher ratios. The Modified Atkins Diet and Low Glycemic Index Treatment are approximately 1:1 and may also be calculated using this program. Once the user has selected a desired ratio, KC will automatically determine the protein, fat, and carbohydrate contents. The user may view these calculations and further adjust protein and carbohydrate content if desired.

The final step is the formulation of the ketogenic meals. The total daily amount of fat, protein, and carbohydrate is divided equally into the number of meals that is determined to be necessary for the individual. The user may select from a list of typical KD meals. The KC will subsequently create the selected meals to meet the diet prescription. Each meal should then be reviewed by the dietitian and adjusted for accuracy. The meals may be easily modified to meet individual preferences by adding additional food items or altering the quantities of foods. The final mathematically balanced meals are used interchangeably.

Classification of foods into food categories allows greater variety. The classic KD uses a standard group of fruit (10% and 15%), and two groups of vegetables (group A and group B). This allows the caregiver to create a variety of meal options from one meal calculation. For example, Figure 1 reveals the calculation of a meal containing chicken, group A vegetables, cream, and butter. A variety of vegetables from the group A list may be interchanged such as broccoli, spinach, or a salad with multiple vegetables.

Figure 1.

KetoCalculator calculation of a single meal

During the course of therapy, the KD may require adjustment in calories or ratio. The user will create a new diet prescription. The KC will save previously calculated meals and allow the user to readjust these to the new diet prescription.

Liquid formulas may also be calculated using the KC. Several options to automatically create standard formulas from commercial products are available in the program. These formulations may also be modified by adding or adjusting ingredients, such as increasing the water content or adding specific oils.

In addition to the meal and snack calculations, the KC also assists in the selection of nutrition supplements. Goals for individual intake are automatically extracted from RDA tables based on the individual's age (National Research Council, 2002). The user may select from a group of products such as multivitamins and calcium supplements and compare the sum of micronutrients from these products to goals. The carbohydrate content is also displayed and tallied to reveal the total contribution of carbohydrate from the chosen supplements.

A separate feature within the program calculates the carbohydrate content of medications based on a directory of 250 commonly used prescription and nonprescription medications. The user is also able to enter new medications into the program to be included in this evaluation.

The KD should be accompanied by sufficient fluid to maintain adequate hydration. The KC will calculate maintenance fluid volume for the individual based on weight using the Holiday-Segar Method. This volume serves as a guide for basic hydration needs. A guide may be created in this feature to organize fluids and meals into a daily schedule to assist the individual in diet management. This guide is also helpful for establishing a schedule for enteral formula feedings.

Additional Features

The user may add additional foods, medications, and supplements into their program. There are two support features for assisting users in the use of the program. A Frequently Asked Questions section is linked to provide guidance. There is also a Help Line which allows the user to submit a question and receive a response within 24 hours.

Currently there are several hundred KC users world-wide. The program is free to registered dietitians. The dietitian may provide a password to the caregiver to access the meal and snack calculation features. This feature also includes digital notification to the dietitian when a caregiver creates new meals and snacks or adjusts existing ones.

This web-based application is stored on a secured server and requires a login and password to enter. The data entry and beta testing for the program was provided by Beth Zupec-Kania.


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Disclosure: The author is a paid consultant to The Charlie Foundation and to Children's Hospital of Wisconsin (Milwaukee, WI), and has received an educational grant from Nutricia North America for development and maintenance of KetoCalculator.