The 500 rule estimates how many grams of carbohydrate one unit of rapid insulin covers. Enter your total daily insulin dose to get your ratio.
Your visual report appears here
Fill in the form and press Calculate. You will get your number, an interpretation chip, and a personalized chart pack drawn instantly in your browser.
- Risk spectrum with your position marked
- Reference ranges from the original publication
- Shareable link, nothing stored
Scientific references
How the 500 rule works
Divide 500 by the total units of insulin you use in a full day, including basal. The answer estimates the grams of carbohydrate matched by one unit of rapid acting insulin at meals.
Why the ratio matters
An accurate ratio keeps post meal glucose steady. Too strong a ratio causes lows after eating, too weak leaves readings climbing for hours.
Understanding your result
- Ratios near 5 mean each unit covers little carbohydrate, seen with insulin resistance
- Ratios around 10 to 15 are common in adults
- Ratios above 20 indicate high insulin sensitivity, common in children and lean athletes
Refining the number
Check glucose two hours after meals. If it lands more than 40 mg/dL above the pre meal value repeatedly, your diabetes team may strengthen the ratio.