How do I get glucose and fructose values from Cronometer?

Open Cronometer, go to the Trends tab, open the Nutrients report, and enable Glucose, Fructose, Sucrose and Starch. Enter those gram values into the calculator to see your ratio.

What is the ideal glucose:fructose ratio for endurance sports?

Research supports ratios between roughly 1:0.8 and 2:1. Modern high-carb fueling often uses 1:0.8 to minimize GI distress while maximizing absorption through both SGLT1 and GLUT5 transporters.

Why does starch count as glucose in the ratio?

Starch is made of glucose polymers. During digestion it breaks down into glucose, so it contributes to the glucose side of the ratio.

How is sucrose counted?

Sucrose is table sugar and is composed of one glucose and one fructose molecule. The calculator splits every gram of sucrose into 0.5 g glucose and 0.5 g fructose.

FUel Calc

Glucose:Fructose Ratio Calculator for Endurance Fueling

Enter your internal sugar values from Cronometer — glucose, fructose, sucrose and starch — to find your optimal fueling ratio for cycling, running and triathlon.

Current Ratio

2.00:1

= 1:0.50

Target 1:0.80

High glucose

Total Glucose

60.0 g

Total Fructose

30.0 g

Action Plan

Add fructose 18.0 g

Current Intake

Upload or paste a nutrition screenshot (mobile or desktop, e.g. Cronometer) — press Ctrl/Cmd+V anywhere and the values are filled in automatically. Text recognition runs 100% on your device and is free forever; no image ever leaves your browser. First scan downloads the OCR engine once and may take a few seconds.

Glucose

Fructose

Sucrose

Starch

Maltose

Lactose

Galactose

Allulose

Target Settings

Preset

Target 1:0.80 · Min 1:0.80 · Max 1:0.80

Optimization Strategy

Adds glucose or fructose to reach target, keeping existing amounts.

How to Use with Cronometer

Open your Cronometer diary and switch to the Trends tab.
Select the nutrient report and enable Glucose, Fructose, Sucrose and Starch.
Copy the gram values for the meal, day or training window you want to analyze.
Paste them into the calculator above and pick a preset (1:0.8, 1:1 or 2:1).
Follow the action plan to add or swap glucose or fructose until you hit the target ratio.

What Each Sugar Type Means

Glucose: The simplest form of sugar absorbed through the SGLT1 transporter. It is the primary fuel for muscles and the brain during exercise. Counts 100% toward the glucose side of the ratio.
Fructose: A fruit sugar absorbed via the GLUT5 transporter, which runs independently of glucose absorption. Adding fructose lets you increase total carbohydrate oxidation beyond glucose alone. Counts 100% toward the fructose side.
Sucrose: Common table sugar made of one glucose and one fructose molecule bonded together. The calculator splits every gram into 0.5 g glucose and 0.5 g fructose.
Starch: A complex carbohydrate made of long glucose chains. Digestion breaks it down into glucose, so it contributes only to the glucose side.
Maltose: Two glucose units linked together. It is rapidly broken down into glucose during digestion and counts 100% toward the glucose side.
Lactose: Milk sugar composed of glucose and galactose. Galactose is absorbed via the SGLT1 pathway, so for this ratio lactose is treated as glucose-side.
Galactose: A single sugar found in dairy and some plant foods. It uses the SGLT1 transporter and is therefore counted on the glucose side.
Allulose: A rare, low-calorie sugar that is not metabolized for energy. It does not contribute to fuel absorption and is excluded from the ratio.

Science Background

The glucose-to-fructose ratio is crucial for intestinal absorption. SGLT1 transporters move glucose and saturate at roughly 60–90 g/h. Adding fructose activates the GLUT5 transporter, which runs in parallel and can raise total carbohydrate oxidation to 90–120 g/h. Current endurance sports research favors a 1:0.8 ratio over the older 2:1 standard because it reduces GI distress while still maximizing fuel availability.

Frequently Asked Questions

Can I use this calculator with food data from apps other than Cronometer?: Yes. Any tracker or nutrition label that lists glucose, fructose, sucrose and starch will work. Just enter the grams into the matching fields.
What happens if glucose or fructose is zero?: If one side is zero, the ratio collapses to the available sugar only. The action plan will recommend adding the missing sugar to reach the chosen target.