How to Use This Calculator
Step 1: Find Your Total Daily Insulin
Add Your Mealtime Insulin
Count all rapid-acting insulin (Humalog, Novolog, Apidra)
Add Your Background Insulin
Include long-acting insulin (Lantus, Levemir, Basaglar, Tresiba)
Get Your Total
Add them together for your total daily dose
Step 2: Use Your Ratio
Count Your Carbs
Look at food labels or use a carb counting app
Divide by Your Ratio
Total carbs ÷ carbs per unit = insulin dose
Take Your Insulin
Give yourself the calculated dose before eating
Check Blood Sugar
Test 2 hours after eating to see if dose was right
How the Calculator Works
The 500 Rule
This calculator uses the "500 Rule" - a simple formula that doctors use to figure out insulin-to-carb ratios.
Start with 500
This is a constant number used in the formula
Divide by Your Total Insulin
500 ÷ your daily insulin = grams per unit
Get Your Ratio
The result tells you how many carb grams 1 unit covers
Example Calculation
If you take:
50 units total per day
Calculate:
500 ÷ 50 = 10
Your ratio is:
1:10
1 unit covers 10g of carbs
Understanding Your Results
Lower ratios mean you need more insulin per carb gram
Understanding Carb Counting
What Are Carbs?
Carbohydrates (carbs) are sugars and starches in food that raise your blood sugar. Counting them helps you take the right amount of insulin.
Foods with Carbs:
- Grains: Bread, pasta, rice, cereal
- Fruits: Apples, bananas, berries, juice
- Dairy: Milk, yogurt (but not cheese)
- Sweets: Candy, cookies, soda
- Starchy veggies: Potatoes, corn, peas
Foods with No Carbs
These foods don't raise blood sugar much and don't need insulin for them.
Carb-Free Foods:
- • Meat & fish: Chicken, beef, fish, eggs
- • Cheese: All types
- • Most veggies: Lettuce, broccoli, peppers
- • Fats: Butter, oil, avocado
- • Water & diet drinks
Things That Affect Your Ratio
Your insulin-to-carb ratio can change based on different things in your life
Things You Can Control
These factors you can manage:
- Exercise makes insulin work better
- Eating healthy foods helps control blood sugar
- Getting enough sleep affects insulin needs
- Managing stress helps blood sugar stay stable
Times to Adjust
You might need different ratios during:
- Growth spurts (you're growing!)
- Being sick or getting infections
- Changes in your activity level
- Hormone changes (like periods)
Tips for Better Blood Sugar Control
Eating Smart
Learn Portion Sizes
Use measuring cups or a food scale to know how much you're eating
Read Food Labels
Check the "Total Carbohydrate" line on nutrition facts
Keep Track
Write down what you eat and your blood sugars to find patterns
Daily Habits
Test Your Blood Sugar
Check before meals and 2 hours after to see if your dose was right
Stay Active
Exercise helps insulin work better (but check blood sugar first!)
Talk to Your Team
Share your blood sugar logs with your doctor or diabetes educator
How to Get Accurate Dosing
Before You Dose
- Check your blood sugar first
- Count all the carbs in your meal or snack
- Use your ratio to calculate your dose
- Double-check your math before injecting
After You Eat
- Test blood sugar 2 hours after eating
- Write down the result in your log
- If blood sugar is often high or low, tell your doctor
- Your ratio might need adjustment as you grow
When to Get Help Right Away
Call 911 or get help immediately if you have:
Severe Low Blood Sugar Signs:
- Can't wake up or very confused
- Having a seizure
- Can't eat or drink safely
- Blood sugar under 54 mg/dL (3.0 mmol/L)
- Passed out or not responding
Severe High Blood Sugar Signs:
- Vomiting and can't keep fluids down
- Trouble breathing or fast breathing
- Very sleepy or confused
- Blood sugar over 400 mg/dL (22 mmol/L)
- Stomach pain or fruity breath smell
Call Your Doctor If:
- Blood sugar is often too high or too low after meals
- You're not sure if your ratio is working
- You have questions about carb counting or dosing