What formula does this calculator use?

For Type 1, TDD = 0.4–0.5 units per kg of body weight. For Type 2 (insulin-naive), TDD = 0.5–0.6 u/kg is a common starting point. The calculator uses the midpoint of each range and rounds to the nearest whole unit.

What is the basal/bolus split?

The standard starting split is 50% of TDD as long-acting basal insulin and 50% as rapid-acting bolus insulin divided equally across three meals (~17% each meal). Some clinicians use a 40/60 or 60/40 split — adjust per your provider.

What is the insulin sensitivity factor (ISF)?

ISF (also called the correction factor) estimates how many mg/dL one unit of insulin lowers blood glucose. The "1700 Rule" for rapid-acting insulin is: ISF = 1700 ÷ TDD. Some protocols use 1500 for regular insulin.

Is this a substitute for medical advice?

No. This tool provides educational estimates based on published weight-based guidelines. Always consult your endocrinologist or diabetes care team before changing your insulin regimen.

Why does my actual dose differ?

Weight-based formulas are starting-point estimates. Actual doses vary with carbohydrate intake, activity level, insulin resistance, concurrent medications, renal function, and individual response.

What is the insulin-to-carb ratio (ICR)?

ICR = 500 ÷ TDD (the "500 Rule"). It tells you how many grams of carbohydrate one unit of rapid-acting insulin covers. For example, TDD = 40 → ICR = 1:12.5 (one unit per 12.5 g carbs).

Total Daily Insulin Calculator

Enter your weight and diabetes type to estimate total daily insulin and see the recommended basal/bolus split.

Patient Details

Body Weight

Diabetes Type

Type 1 Type 2

Insulin Regimen

Rapid-acting bolus Regular insulin

Enter your weight and click Calculate to see your insulin estimates.

Summary

Total Daily Insulin (TDD) is the sum of all insulin units a person takes in 24 hours, including both basal (background) and bolus (mealtime) doses. Weight-based formulas — 0.4–0.5 u/kg for Type 1 and 0.5–0.6 u/kg for Type 2 — give clinicians a safe starting estimate that is then refined through blood glucose monitoring. This calculator applies those guidelines and also derives the insulin sensitivity factor (ISF) and insulin-to-carb ratio (ICR) so you can see how the numbers connect.

How it works

Weight is converted to kilograms if entered in pounds.
TDD is computed using the midpoint multiplier for the selected diabetes type.
Basal dose = TDD × 50%; bolus per meal = TDD × 50% ÷ 3.
ISF = 1700 ÷ TDD (rapid-acting correction factor).
ICR = 500 ÷ TDD (grams of carb covered per unit).

Use cases

Estimating a starting TDD when initiating insulin therapy.
Verifying whether a current regimen aligns with weight-based guidelines.
Splitting a known TDD into basal and bolus portions.
Calculating an insulin sensitivity factor (ISF) from TDD.
Teaching patients how basal-bolus dosing is derived.
Cross-checking a dose adjustment before a clinic visit.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu