Frequently Asked Questions

The calculators use standard published formulas (ADA/AACE-referenced) to produce starting-point estimates. They apply population-level averages and cannot account for individual factors like activity level, diet composition, stress, illness, kidney function, or medication interactions. Treat every output as an educational estimate — not a prescription — and always confirm with your healthcare provider before making any dosing change.

We use weight-based TDD estimation (0.4–0.6 u/kg/day per ADA), the 500 Rule for carb-to-insulin ratio, the 1800 Rule for insulin sensitivity factor (rapid-acting), the 1500 Rule for Regular insulin, and the standard HOMA-IR and QUICKI formulas for insulin resistance. Full documentation with primary sources is on our Methodology page.

No. Every calculation runs entirely in your browser using client-side JavaScript. No weight, blood glucose, insulin dose, or any other health data is transmitted to any server, stored in a database, or shared with third parties. The calculations happen locally on your device. See our Privacy Policy for full details.

The default is mg/dL (used in the United States). A toggle button lets you switch to mmol/L (used in Canada, the UK, Australia, and most of Europe). The calculator converts your existing inputs automatically when you toggle — you do not need to convert manually.

Both estimate insulin-to-carb ratio (ICR = divisor ÷ TDD). The 500 Rule is most widely cited for rapid-acting insulin analogs (lispro, aspart, glulisine). The 450 Rule uses 450 instead and is sometimes preferred for Regular (human) insulin, or for individuals who find the 500 Rule underestimates how much insulin they need per gram of carb. The right number for you is determined through real-world adjustment with your care team. Our calculators offer both.

Insulin sensitivity factor (ISF), also called correction factor, estimates how much blood glucose (mg/dL) drops per 1 unit of insulin. It is calculated using the 1800 Rule for rapid-acting analogs: ISF = 1800 ÷ TDD. Example: TDD = 40 → ISF = 45 mg/dL per unit. This means if you need to lower blood glucose by 90 mg/dL, you might need ~2 units as a correction. Real ISF varies by time of day and individual — use this as a starting point only.

Correction Dose = (Current Blood Glucose − Target Blood Glucose) ÷ ISF. For example: current BG = 220 mg/dL, target = 100 mg/dL, ISF = 45 → (220 − 100) ÷ 45 = 2.7 → rounded to 2.5 units. Important: this formula does not subtract insulin on board (IOB) from recent doses. Clinical bolus calculators in insulin pumps and CGM devices apply IOB, which this simple formula does not. Always factor in recent insulin before correcting.

For most adults, ADA guidelines suggest a starting dose of 0.4–0.6 units per kg per day. A 70 kg adult might start at 28–42 units/day. People with Type 1 diabetes often use 0.4–0.5 u/kg; insulin-naïve Type 2 patients may start at 0.2 u/kg or a fixed 10 units/day and titrate up. Actual TDD varies widely — some people use considerably more — and is always determined by individual titration with your care team.

Pediatric insulin dosing requires specialist supervision and cannot be reliably derived from adult weight-based formulas. Children's insulin sensitivity, activity patterns, growth, and pubertal changes all affect dosing in ways these tools do not model. We offer a Pediatric Insulin Dosing Calculator for educational reference, but it carries a strong note: always work with a pediatric endocrinologist or diabetes care team for children and adolescents. This is not optional.

Insulin requirements change significantly throughout pregnancy due to placental hormones. Our pregnancy calculator uses adjusted dosing factors published in obstetric literature, but pregnant individuals managing insulin must work closely with an OB-GYN and endocrinologist. The educational estimates on this site are not a substitute for that specialist care. Blood glucose targets in pregnancy are also tighter than general diabetes targets.

Our dog insulin calculator uses veterinary dosing references for educational purposes. It should only ever be used alongside guidance from a licensed veterinarian. Pet insulin dosing is distinct from human insulin dosing — the insulin types, concentrations, and protocols differ. Never adjust your pet's insulin without veterinary guidance.

This is a medical emergency if you have or develop symptoms of hypoglycemia. Symptoms include shakiness, sweating, confusion, rapid heartbeat, or loss of consciousness. If conscious and able to swallow, treat with fast-acting carbohydrates (glucose tablets, juice, regular soda). If unconscious or unable to swallow, call 911 (US) or your local emergency number immediately. Do not use a calculator during an emergency — call for help.

DKA is a life-threatening complication most common in Type 1 diabetes, triggered by insufficient insulin. Signs include: very high blood glucose (typically >250 mg/dL), high ketones in urine or blood, fruity-smelling breath, nausea and vomiting, abdominal pain, rapid or labored breathing, and confusion. DKA requires emergency medical treatment — call 911 or go to an emergency room immediately.