Total Daily Dose (TDD) Insulin Calculator
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — October 2026
Calculate your total daily insulin dose three ways: sum a real day from your insulin log (most accurate), enter a known TDD, or estimate from body weight — then derive your carb ratio and sensitivity factor. Educational use only.
📊 TDD Calculator
Results
Estimated Total Daily Dose
units/day
units/day
g carbs per unit
mg/dL per unit
How to Use the Total Daily Dose (TDD) Insulin Calculator
Choose Your Mode
"From Insulin Log" adds up a real day of doses and gives the most accurate TDD. "Known TDD" takes a total you already have. "From Weight" estimates a starting TDD for someone new to insulin.
Enter Weight or TDD
In log mode, enter basal units and each meal bolus. In weight mode, the diabetes type sets the dose factor. In known-TDD mode, type the daily total.
Select Insulin Type
Rapid-acting analogs use the 1800 Rule for ISF; Regular (human) insulin uses the 1500 Rule.
Review Derived Values
See TDD, basal/bolus split, insulin-to-carb ratio, and sensitivity factor — all computed from your TDD in one step.
Verify the Formula
Every result shows the exact calculation. Share it with your provider to discuss how your actual values compare.
Titrate With Your Team
Use the estimate as a starting point — your actual TDD is refined through weeks of titration against real blood glucose data.
What Is Total Daily Dose and Why Does It Matter?
Total daily dose (TDD) is the number of insulin units a person uses in 24 hours: long-acting basal insulin plus every mealtime and correction bolus. Diabetes teams use TDD as the base for the carb ratio, the correction factor and the basal rate. A correct TDD gives sound starting ratios. A wrong TDD shifts every one of them in the same direction.
TDD from Weight
The ADA Standards of Care 2026 give typical totals of 0.4–1 u/kg/day and name 0.5 u/kg/day as the usual start for a stable adult with type 1 diabetes. Type 2 patients who start basal insulin alone begin at 0.1–0.2 u/kg/day. This calculator uses 0.5 for type 1 and 0.2 for an insulin-naïve type 2 start. Worked example: 80 kg × 0.5 = 40 units/day.
Empirical TDD (If Already on Insulin)
If you already take insulin, adding up your actual doses over a representative week gives a more accurate TDD than any formula. The step-by-step dose calculation guide works through the same arithmetic with a full example. Log example: breakfast 8 u + lunch 5 u + dinner 7 u + long-acting 20 u = 40 units/day. Pump users can read a 7-day average TDD straight from the pump history screen.
Derived Values from TDD
Once TDD is known, carb ratio and sensitivity factor follow directly. A TDD of 40 gives ICR = 12.5 g/unit and ISF = 45 mg/dL (2.5 mmol/L)/unit (rapid-acting).
Basal–Bolus Split
Starting plans split TDD about 50/50 between basal and bolus insulin, and the UCSF Diabetes Teaching Center gives basal 40–50% of the total. Measured needs often run lower on a pump. A Diabetes Care study of 35 type 1 pump users with no remaining insulin production found basal needs of 27.7% of TDD, close to 30%. A basal share far above 50% often hides missing mealtime insulin, which the ADA calls overbasalization.
| Setting | Basal share of TDD | Source |
|---|---|---|
| New injection plan (MDI) | ≈ 50% | ADA Standards of Care 2026 |
| Patient teaching guide | 40–50% | UCSF Diabetes Teaching Center |
| Type 1 on a pump, measured | ≈ 28–30% | Kuroda et al., Diabetes Care 2011 |
TDD Chart: Carb Ratio and Sensitivity Factor by Total Daily Dose
Each row applies the 500 rule for the carb ratio and the 1800 rule for rapid-acting insulin. The mmol/L column uses the 100 rule (1800 ÷ 18). Use the row nearest your own TDD as a starting point to check against your glucose readings.
| TDD (units/day) | Basal ≈ 50% | Carb ratio (500 ÷ TDD) | ISF mg/dL (1800 ÷ TDD) | ISF mmol/L (100 ÷ TDD) |
|---|---|---|---|---|
| 20 | 10 u | 1 u : 25 g | 90 | 5.0 |
| 25 | 12.5 u | 1 u : 20 g | 72 | 4.0 |
| 30 | 15 u | 1 u : 16.7 g | 60 | 3.3 |
| 35 | 17.5 u | 1 u : 14.3 g | 51 | 2.9 |
| 40 | 20 u | 1 u : 12.5 g | 45 | 2.5 |
| 50 | 25 u | 1 u : 10 g | 36 | 2.0 |
| 60 | 30 u | 1 u : 8.3 g | 30 | 1.7 |
| 70 | 35 u | 1 u : 7.1 g | 26 | 1.4 |
| 80 | 40 u | 1 u : 6.3 g | 23 | 1.3 |
| 100 | 50 u | 1 u : 5 g | 18 | 1.0 |
Total Daily Dose (TDD) Insulin Calculator: Limitations & Safety Notes
- A weight-based TDD is a starting estimate. Real requirement emerges over weeks of titration and is frequently well outside the initial figure.
- Appropriate ranges differ sharply by patient type — an insulin-naive Type 2 patient starts far lower than someone with Type 1.
- Reduced kidney function lowers insulin requirement because injected insulin is cleared renally; glucocorticoids raise it substantially.
- A TDD derived from your insulin log is only as reliable as the log. Missed entries and unrecorded corrections both bias it downward.
TDD is the number nearly every other formula starts from, which is why the full diabetes calculator collection gives it a central place.
Sources & References
- American Diabetes Association. Standards of Care in Diabetes — 2026. Link
- Walsh J, Roberts R, Bailey T. "Guidelines for Optimal Bolus Calculator Settings." J Diabetes Sci Technol. 2011;5(1):129–135.
- Davidson PC et al. "Analysis of guidelines for basal-bolus insulin dosing." Endocr Pract. 2008;14(9):1095–1101.
- Kuroda A, et al. "Basal Insulin Requirement Is ∼30% of the Total Daily Insulin Dose in Type 1 Diabetic Patients Who Use the Insulin Pump." Diabetes Care. 2011;34(5):1089. Link
- UCSF Diabetes Teaching Center. Calculating Insulin Dose. Link
- U.S. FDA. Humulin R U-500 prescribing information (indicated for patients requiring more than 200 units of insulin per day). Link
Written by Ryan Mitchell · Last updated: October 2026
Frequently Asked Questions: Total Daily Dose (TDD) Insulin Calculator
What is total daily dose of insulin?
TDD is the total insulin units used in 24 hours — all basal and bolus doses combined. It is the foundation for calculating insulin-to-carb ratio (500 ÷ TDD) and insulin sensitivity factor (1800 ÷ TDD). A 70 kg adult with Type 1 might have a TDD of ~35 units/day, while someone with significant insulin resistance uses 80+ units/day. TDD is determined by actual usage and clinical titration, not formulas alone.
How do I calculate my total daily insulin dose?
Two methods: (1) Formula estimate: TDD = weight (kg) × 0.5 u/kg/day — a starting point for those new to insulin. (2) Empirical method: If you already inject, add up all units taken over 3–7 representative days and divide by the number of days. The empirical method is more accurate because it reflects your actual insulin requirements, not a population average.
What is a high total daily dose of insulin?
No single cut-off exists, because body weight and insulin resistance both drive TDD. A total above about 1 u/kg/day points to marked insulin resistance, and some people with type 2 diabetes and obesity need 100–200+ units a day. Above 200 units a day, prescribers consider Humulin R U-500, which the FDA label reserves for that group. Concentrated U-200 and U-300 products also cut injection volume. This calculator flags any TDD above 500 u/day as implausible.
How is TDD used to calculate carb ratio and ISF?
Carb ratio (ICR) = 500 ÷ TDD — gives grams of carbohydrate covered by 1 unit of rapid-acting insulin. Insulin sensitivity factor (ISF) = 1800 ÷ TDD for rapid-acting analogs — gives mg/dL blood glucose drop per unit. Both are starting estimates. Real-world ICR and ISF need verification: check 2-hour postprandial readings (for ICR) and correction dose response (for ISF) with your care team.
Should I use calculated or actual TDD in this tool?
If you already take insulin regularly, your actual empirical TDD (average over several days) will produce more accurate ICR and ISF estimates than the weight-based formula. The weight formula is best for people just starting insulin who don't yet have usage data. Use the "Enter Known TDD" mode in the calculator above if you know your real daily total.
What is a normal total daily dose of insulin?
No single normal value exists. The ADA gives typical totals of 0.4–1 unit per kg per day, so a 70 kg adult with type 1 diabetes often lands between 28 and 70 units, with 35 units at the usual 0.5 u/kg start. Newly diagnosed type 1 adults in the honeymoon phase may need only 0.2–0.6 u/kg/day. Type 2 totals vary much more because insulin resistance varies.
What percentage of TDD should be basal insulin?
Most starting plans give about 50% of TDD as basal insulin, and the UCSF Diabetes Teaching Center lists 40–50%. Measured needs are often lower: a Diabetes Care study of type 1 pump users found basal made up about 28% of TDD. A basal share well above 50% usually means mealtime doses are too small.