Humalog Dose Calculator
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — October 2026
Calculate your exact Humalog (insulin lispro) dose for meals and high blood sugar correction using your carb ratio and sensitivity factor.
🍽️ Humalog Dose Calculator
ICR = grams of carbs covered by 1 unit. Don't know yours? Use our Carb Ratio Calculator (500 ÷ TDD).
+ Add pre-meal correction dose (optional)
Don't know yours? Calculate ISF (1800 ÷ TDD)
Estimated Humalog Dose
Total estimated bolus (carb dose + correction if entered)
(carbs ÷ ICR)
(if BG entered)
Humalog (lispro) starts working in about 15 minutes, peaks at about 1 hour and lasts roughly 3–5 hours. The curve is scaled to your total dose. The label says to inject within 15 minutes before a meal or right after it.
How to Use the Humalog Dose Calculator
Count Your Carbs
Total the grams of carbohydrate in your planned meal. Use food labels, a carb counting app, or a dietitian's guidance.
Enter Your ICR
Input your insulin-to-carb ratio. If you don't know it, our Carb Ratio Calculator estimates it from TDD using the 500 Rule.
Add Correction (Optional)
If your pre-meal BG is above target, expand the correction section. Enter current BG, target BG, and your ISF.
Calculate
Your carb bolus, correction bolus (if entered), and combined total are displayed with the full formula.
Check Insulin on Board
Before dosing any correction, subtract active insulin from recent doses (IOB). This calculator does not model IOB.
Confirm With Your Team
Your actual ICR is set by your care team through real-world testing — use this estimate as a discussion tool, not a prescription.
How Humalog Insulin Dosing Works
Humalog insulin — also called prandial or bolus insulin — is the rapid-acting dose taken before or at meals to handle the blood glucose rise from carbohydrates eaten. It is one part of a full bolus: some people also add a correction component if their pre-meal reading is above target.
Carb Bolus Formula
Example: 75g carbs ÷ ICR of 12 = 6.25 → rounded to 6.5 units. ICR is your insulin-to-carb ratio: the number of grams one unit covers. Source: Walsh et al., J Diabetes Sci Technol. 2011.
Optional Correction Added to Meal Bolus
If pre-meal BG = 180 mg/dL (10.0 mmol/L), target = 100, ISF = 40: correction = (180 − 100) ÷ 40 = 2 units. Total bolus = carb dose + 2. Important: subtract any insulin on board (IOB) before adding a correction.
What Is ICR and Where Does It Come From?
ICR is estimated using the 500 Rule: divide 500 by your total daily dose. If TDD = 40, ICR ≈ 12.5g/unit. This is a starting estimate — your real ICR is verified by checking your blood glucose 2 hours after meals and adjusting. An ICR that's too aggressive (too low) causes post-meal hypoglycemia; one that's too lenient (too high) causes persistent post-meal hyperglycemia. Many people also have different ICRs at different meals due to time-of-day insulin resistance variations (e.g., more resistant in the morning).
This calculator does not account for fat and protein in meals. High-fat meals slow carbohydrate absorption, potentially causing late glucose spikes hours after eating. Some people with Type 1 use extended or dual-wave boluses for such meals — discuss this with your diabetes educator.
Humalog Meal Dose Chart (Carbs × Carb Ratio)
Find your meal's carb grams down the side and your ICR across the top — the cell is your Humalog carb bolus, in units. Deeper colour = larger dose. Rounded to the nearest ½ unit; add any correction separately.
| Carbs ↓ / ICR → | 1:8 | 1:10 | 1:12 | 1:15 |
|---|---|---|---|---|
| 15 g | 2 | 1.5 | 1.5 | 1 |
| 30 g | 4 | 3 | 2.5 | 2 |
| 45 g | 5.5 | 4.5 | 4 | 3 |
| 60 g | 7.5 | 6 | 5 | 4 |
| 75 g | 9.5 | 7.5 | 6.5 | 5 |
| 90 g | 11.5 | 9 | 7.5 | 6 |
Don't know your ratio? Estimate it on the Carb Ratio Calculator (500 ÷ TDD). This chart assumes rapid-acting lispro; Regular insulin uses the 450 Rule.
Humalog Correction Chart (Sliding Scale by ISF)
Many people search for a "Humalog sliding scale". A fixed hospital scale only fits the patient it was written for. A correction chart built from your own insulin sensitivity factor (ISF) does the same job and scales to you. Each cell applies (current glucose − 120) ÷ ISF, rounded to the nearest half unit, for a target of 120 mg/dL (6.7 mmol/L).
| Glucose (mmol/L) | ISF 30 | ISF 40 | ISF 50 | ISF 60 |
|---|---|---|---|---|
| 150 mg/dL (8.3) | 1 | 1 | 0.5 | 0.5 |
| 180 mg/dL (10.0) | 2 | 1.5 | 1 | 1 |
| 210 mg/dL (11.7) | 3 | 2.5 | 2 | 1.5 |
| 240 mg/dL (13.3) | 4 | 3 | 2.5 | 2 |
| 270 mg/dL (15.0) | 5 | 4 | 3 | 2.5 |
| 300 mg/dL (16.7) | 6 | 4.5 | 3.5 | 3 |
| 350 mg/dL (19.4) | 7.5 | 6 | 4.5 | 4 |
| 400 mg/dL (22.2) | 9.5 | 7 | 5.5 | 4.5 |
Subtract any insulin still on board from a recent dose before you take a correction. Standard KwikPens dial whole units, so round a half unit down if you are unsure. Glucose above 250 mg/dL (13.9 mmol/L) with ketones needs a call to your care team, not just a correction.
Humalog Strengths, Pens and Dosing Rules (FDA Label)
Humalog is insulin lispro from Eli Lilly. Every form below holds the same insulin, but the pens differ in how finely they dial and how much they deliver in one injection.
| Form | Strength / size | Dial step | Max per injection |
|---|---|---|---|
| Vial | U-100, 10 mL (1,000 units) or 3 mL (300 units) | Syringe markings | Syringe size |
| KwikPen | U-100, 3 mL (300 units) | 1 unit | 60 units |
| Tempo Pen (connects to an app) | U-100, 3 mL (300 units) | 1 unit | 60 units |
| Junior KwikPen | U-100, 3 mL (300 units) | 0.5 unit | 30 units |
| U-200 KwikPen | U-200, 3 mL (600 units) | 1 unit | 60 units |
| Cartridge (reusable pen) | U-100, 3 mL (300 units) | Per pen | Per pen |
- Timing: inject within 15 minutes before a meal or immediately after it.
- Discard 28 days after opening, for every vial, pen and cartridge, even if insulin is left.
- U-200 pen: dial your usual number of units; the pen does the conversion. Never draw U-200 into a syringe, use it in a pump, give it IV or mix it with another insulin.
- Pumps: Humalog U-100 works in insulin pumps. Change the insulin in the reservoir at least every 7 days, and keep the reservoir below 98.6 °F (37 °C).
- Mixing: Humalog U-100 may be mixed only with NPH insulin in a syringe. Draw Humalog first and inject right away.
- Insulin Lispro (unbranded) from Lilly is the same product at a lower list price. Admelog is a different company's lispro, and Lyumjev is a faster lispro formulation; neither is a unit-for-unit swap without your prescriber.
How Humalog Compares to Other Rapid Insulins
Approximate action profiles over 6 hours. The bar is the working window (onset → end); the orange line marks peak activity. Humalog, NovoLog and Apidra behave almost identically; Fiasp and Lyumjev act sooner. Basal, supply and timing questions for lispro users are covered by our insulin calculator suite.
Full onset/peak/duration data for every insulin class is in Insulin Types Explained. Timing your dose to these curves: Insulin Timing Calculator.
Sources & References
- Walsh J, Roberts R, Bailey T. "Guidelines for Optimal Bolus Calculator Settings in Adults." J Diabetes Sci Technol. 2011;5(1):129–135.
- American Diabetes Association. Standards of Care in Diabetes — 2026. Section 9. Link
- Hirsch IB. "Insulin Analogues." N Engl J Med. 2005;352:174–183.
- Eli Lilly and Company. Humalog (insulin lispro) injection, prescribing information, revised 01/2026. Link — source of the timing, pen, pump, mixing and storage rules.
Written by Ryan Mitchell · Last updated: October 2026
Frequently Asked Questions: Humalog Dose Calculator
How do I calculate my Humalog dose?
Humalog bolus = grams of carbohydrates ÷ insulin-to-carb ratio (ICR). If your ICR is 1:10 and you eat 60g carbs, bolus = 60 ÷ 10 = 6 units. If your pre-meal BG is above target, add a correction: (current BG − target BG) ÷ ISF. Subtract any insulin on board (IOB) from the correction before dosing. Always confirm your ICR with your diabetes care team.
What is insulin-to-carb ratio?
ICR is the number of grams of carbohydrate covered by one unit of rapid-acting insulin. A ratio of 1:10 means one unit covers 10g carbs. The 500 Rule (500 ÷ TDD) estimates ICR as a starting point, then refined through real-world testing. ICR often differs by meal time — many people need a lower ratio (more insulin) at breakfast due to morning insulin resistance from cortisol and growth hormone peaks.
Should I add a correction dose to my Humalog bolus?
If your pre-meal BG is above your target, adding a correction to the carb bolus is common practice. Total bolus = carb bolus + correction. However, you must subtract insulin on board (IOB) from any correction first to avoid stacking doses. This calculator adds the correction to the carb bolus but does not model IOB — your pump or CGM system may track IOB automatically. Discuss stacking precautions with your care team.
How many carbs does one unit of insulin cover?
The 500 Rule estimates this: 500 ÷ TDD. If TDD = 50 units, one unit covers approximately 10g of carbs. This ranges widely — from 5–6g per unit for people with high insulin requirements to 20+ grams per unit for those who are very insulin-sensitive. Your actual ratio is determined through careful monitoring with your diabetes care team, not by formula alone.
Does fat and protein affect mealtime insulin dose?
Yes, significantly. High-fat meals slow gastric emptying and carbohydrate absorption, causing delayed glucose spikes 2–5 hours after eating. High-protein meals can also raise blood glucose, especially in Type 1 diabetes, due to gluconeogenesis. Standard carb-counting bolus calculators do not account for fat or protein. Many people with Type 1 on pumps use extended boluses (dual-wave or square-wave) for high-fat meals like pizza. Your diabetes educator can advise on strategies.
When should I take Humalog: before or after eating?
The FDA label says to inject Humalog within 15 minutes before a meal or immediately after a meal. Many people with type 1 diabetes inject 10–15 minutes before eating to blunt the post-meal rise. Injecting right after the meal suits a child or adult who may not finish the plate, because you can dose for what was actually eaten.
What is the maximum dose of Humalog per injection?
The Humalog U-100 KwikPen, Tempo Pen and U-200 KwikPen each deliver up to 60 units per injection in 1-unit steps. The Junior KwikPen delivers up to 30 units in half-unit steps. A larger dose needs two injections, or a vial and syringe. There is no fixed daily maximum; the right total is set by your care team.