Insulin Bolus Calculator
Estimate the insulin dose needed for your meals and glucose corrections.
Critical Medical Warning
This tool is only an estimative guide. ALWAYS verify the result with your glucometer or insulin pump before administering the dose.
Consult with your endocrinologist to determine your correct configuration values (Ratio, Sensitivity, Target).
📱 Today's Data
Units remaining from previous doses
Result will be rounded to selected step
📊 Suggested Dose
DANGER: Hypoglycemia
Your glucose is very low (<70 mg/dL). DO NOT administer insulin. Consume fast-acting carbohydrates immediately.
✓ Always verify with your glucometer or pump before administering
💡 About Bolus Calculation
What is an insulin bolus? It's the amount of rapid-acting insulin you administer to cover the carbohydrates in a meal and/or correct elevated glucose.
Formulas used:
- • Meal Dose: Carbohydrates (g) ÷ ICR
- • Correction Dose: (Current Glucose - Target) ÷ ISF
- • Total: Meal Dose + Correction Dose - Active Insulin
Note: ICR, ISF, and Target values are personal and must be determined by your endocrinologist. This calculator is only a support tool.
Insulin Therapy Master Guide: Understanding Basal-Bolus Treatment
Basal-Bolus insulin therapy attempts to mimic how a healthy pancreas releases insulin. It is the gold standard for Type 1 Diabetes treatment and increasingly common in Type 2. To master this calculator, you must first understand the two vital functions of insulin in your body.
1. Basal Insulin (Background)
This is the "insulin for living". Even without eating, your liver constantly releases glucose to keep your body functioning. Basal insulin (Lantus, Levemir, Tresiba, or basal rate in pumps) covers this liver production. If your basal is set correctly, your glucose should remain stable (neither rising nor falling drastically) while you sleep or skip a meal. This calculator does NOT calculate basal; it assumes your basal is already optimized.
2. Bolus Insulin (Fast Acting)
This is the "insulin for eating and correcting". Rapid-acting insulin (Humalog, Novorapid, Fiasp) is used in two specific situations that this tool calculates:
- Prandial Bolus (Meal Coverage): Insulin needed to "process" the carbohydrates you are about to eat. Without it, glucose would rise rapidly after eating (postprandial hyperglycemia). Calculated using your Insulin-to-Carb Ratio (ICR).
- Correction Bolus (Sensitivity Factor): Extra insulin needed if your glucose is already high before eating. It "pushes" blood sugar down toward your target range. Calculated using your Insulin Sensitivity Factor (ISF).
Key Concept:
A total dose often combines both: you cover what you eat AND correct if you are high. If you are low, the calculator will subtract insulin to prevent hypoglycemia.
Technical Glossary for Expert Patients
Your 'Carbohydrate Ratio'. Indicates how many grams of carbohydrates are covered by 1 single unit of insulin. For example, an ICR of 1:10 means you need 1 unit for every 10g of carbs. A LOWER number (e.g. 1:5) indicates higher resistance (needs more insulin), while a HIGHER number (e.g. 1:20) indicates higher sensitivity. This value often varies between breakfast, lunch, and dinner.
Your 'Sensitivity Factor' (also called Correction Factor). Indicates how many mg/dL your glucose will drop with 1 extra unit of insulin. If your ISF is 50, one unit will drop you from 200 to 150 mg/dL. It is crucial for calculating corrections safely. If you correct and drop too fast, your ISF might be set too low (too aggressive).
The magic number you aim to reach. Usually 100 mg/dL or 110 mg/dL. The bolus calculator will use this value to determine how much correction insulin you need. If you are below this target but above hypoglycemia, the calculator might suggest a 'negative correction' (subtracting insulin from the meal) to gently bring you to this level.
Rapid insulin lasts between 3 to 5 hours in the body. IOB is the amount of insulin from previous doses that is STILL working in your system. Ignoring IOB is the #1 cause of hypoglycemia due to 'insulin stacking'. If you inject 5 units at 12:00 and want to correct at 14:00, you still have active units that must be subtracted from the new calculation.
Safety Protocol: 15/15 Rule for Hypoglycemia
If the calculator alerts you of Hypoglycemia (<70 mg/dL), STOP THE INSULIN CALCULATION and follow these universally accepted steps:
- CHECK: Confirm the value with a second measurement if you don't have clear symptoms but the sensor reads low.
-
15 GRAMS: Immediately consume 15 grams of FAST-acting carbohydrates.
- 1/2 cup of juice or regular soda (not diet).
- 1 tablespoon of sugar or honey.
- 3-4 glucose tablets.
- 15 MINUTE: Wait exactly 15 minutes by the clock. Let the body absorb the sugar. Do not eat more even if you are hungry.
-
REPEAT: Measure again.
- Still under 70? -> Repeat the 15g and wait 15 min.
- Above 70? -> Eat a small complex carb + protein snack to stabilize.
Frequently Asked Questions (FAQ)
¿Why do I still have high spikes after eating if I use the calculator?
It might be 'Timing'. Rapid insulin takes 15-20 minutes to start working. If you eat immediately after injecting, the carbs hit your blood before the insulin. Try injecting 15-20 minutes BEFORE eating (Pre-bolus).
¿How do I know if my ratios (ICR/ISF) are correct?
Do fasting tests or controlled meal tests. If 2 hours after eating your glucose returns to your target range (+/- 30 mg/dL from start), your ratio is correct. If you always stay high, your ratio is weak. If you drop low, it's too strong. Change values only by 10% at a time and under medical supervision.
¿What is 'insulin stacking'?
It's the mistake of injecting a new correction dose when the previous one is still active. If you correct, wait at least 3-4 hours before correcting again, or ensure you enter the correct 'IOB' in this calculator so it subtracts what is still circulating.
¿Can I use this for NPH or Regular insulin?
NO. This tool is calibrated for the pharmacokinetics of ultra-rapid insulin analogs (Humalog, Novorapid, Apidra, Fiasp). Regular and NPH insulin have very different action peaks and are dangerous if calculated with this logic.
¿I counted carbs wrong, what do I do?
If you ate MORE than calculated, you can inject the difference now. If you ate LESS, you must consume fast carbs immediately to cover the extra insulin you already administered. Carb counting is a skill that improves with practice.
¿Can I use this for children?
The mathematical logic is the same, but children are much more sensitive to small doses. For small children, insulin pumps or half-unit pens (0.5u) are recommended, as 1-unit rounding can be excessive. Always verify the 'Dose Step Size' configuration in this tool.