Our Methodology
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — September 2026
Every calculator on this site implements a published, citable clinical formula — nothing proprietary, nothing invented. This page documents where each formula comes from, how we build and test the tools, and what they can and cannot do.
Four Principles
Published Formulas Only
Each tool implements formulas from clinical guidelines or peer-reviewed literature. The source is cited on the page that uses it.
Show the Math
Every result prints the exact calculation used, so users and clinicians can verify each number by hand.
Conservative Defaults
Where guidelines give ranges, defaults sit at the midpoint or the conservative end (e.g., 0.5 u/kg TDD; 0.2 u/kg for insulin-naïve Type 2).
Privacy by Design
All calculation runs in your browser. No health values you enter are transmitted or stored by us.
Formula Sources
| Formula | Definition | Primary source |
|---|---|---|
| Weight-based TDD | 0.4–0.6 u/kg/day starting range; 0.2 u/kg insulin-naïve T2 | ADA Standards of Care, Section 9 |
| Basal/bolus split | 40–50% basal, 50–60% bolus | ADA / AACE algorithms |
| 500 Rule (ICR) | ICR = 500 ÷ TDD (rapid-acting) | Walsh & Roberts, Using Insulin |
| 450 Rule (ICR) | ICR = 450 ÷ TDD (Regular insulin) | Walsh & Roberts, Using Insulin |
| 1800 Rule (ISF) | ISF = 1800 ÷ TDD (rapid-acting) | Davidson et al., Endocr Pract 2008 |
| 1500 Rule (ISF) | ISF = 1500 ÷ TDD (Regular insulin) | Davidson et al., Endocr Pract 2008 |
| Correction dose | (Current BG − Target BG) ÷ ISF | ADA Standards of Care |
| HOMA-IR | (Glucose mg/dL × Insulin µU/mL) ÷ 405 | Matthews et al., Diabetologia 1985 |
| QUICKI | 1 ÷ [log(insulin) + log(glucose)] | Katz et al., JCEM 2000 |
| GMI | 3.31 + 0.02392 × mean glucose (mg/dL) | Bergenstal et al., Diabetes Care 2018 |
| eAG / HbA1c | eAG = 28.7 × A1c − 46.7 | Nathan et al. (ADAG), Diabetes Care 2008 |
| Glucose unit conversion | mg/dL = mmol/L × 18.018 | Molecular weight of glucose (180.16 g/mol) |
| Insulin units ↔ mL | mL = units ÷ concentration (U-40/U-100/U-500) | Manufacturer labeling / ISMP |
| Warsaw method (FPU) | 1 FPU = 100 kcal fat/protein → extended bolus | Pańkowska et al. |
| DKA / drip protocols | 0.05–0.1 u/kg/h IV infusion frameworks | ADA consensus / institutional protocols |
Each calculator page carries its own reference list; this table is the master index.
Build & Review Process
- Source first. A tool is only built if a published formula exists for it. Where multiple rules exist (500 vs 450), the tool states which it uses and when each applies.
- Cross-checked implementation. Formula code lives in one shared library (
calc-core.js) with the citation in a comment above each function, and outputs are spot-checked against hand calculations and published worked examples. - Plausibility guards. Inputs outside physiologic ranges (weight, glucose, TDD, carbs) trigger warnings rather than silent results.
- Safety framing. Every page carries an educational-use disclaimer, an emergencies banner, and explicit "confirm with your care team" steps — dosing tools are deliberately framed as estimate explainers, not dose prescribers.
- Review cadence. Content is reviewed against the current ADA Standards of Care in Diabetes annually, and when major guideline updates publish. Each page shows its "Last reviewed" date.
Our Medical Review Process
Clinical content on this site is reviewed by a licensed physician. Since August 2026, that reviewer has been Dr. Chhaya Makhija, MD, DipABLM, a triple board-certified physician in Internal Medicine, Endocrinology & Metabolism and Lifestyle Medicine, and founder of Unified Endocrine & Diabetes Care in Fresno, California. She is engaged as an independent reviewer. Our five veterinary calculators fall outside her scope of practice and are not covered by her review.
What the reviewer checks
- Formula accuracy — that each calculator implements its cited published formula correctly (TDD, insulin-to-carb ratio, correction factor, HOMA-IR, GMI and the rest).
- Guideline alignment — that dose ranges, thresholds and interpretation bands match current ADA Standards of Care and the other sources cited on each page.
- Safety messaging — that disclaimers, plausibility warnings and emergency guidance are present, correct and prominent on dosing tools.
- Framing — that every output reads as an educational estimate rather than a prescription.
What medical review does not mean
Review confirms that the published formulas and safety framing are clinically sound. It does not make any calculator a medical device, and it does not create a doctor–patient relationship between Dr. Walker and any reader. He does not see your inputs — every calculation runs locally in your browser — and he does not provide individual medical advice through this site.
Review cadence and corrections
- Clinical content is re-reviewed at least annually, and sooner when the ADA Standards of Care or another cited guideline is updated.
- New calculators and guides are reviewed before or shortly after publication; reviewed pages carry a "Medically reviewed by" byline with the review month.
- Reported errors are treated as priority work. Anyone can contact us to flag an inaccuracy, and substantive clinical corrections are escalated to the medical reviewer.
- Pages that have not yet been reviewed do not carry a medical-review byline.
Who Maintains This Site
insulin-calculator.org is written and maintained by founder Ryan Mitchell, drawing on a background in the healthcare and pharmaceutical industry. Ryan is not a licensed clinician — he researches and writes the content against the published sources listed above, and clinical accuracy is verified separately by our medical reviewer. Editorial decisions are kept independent of advertising.
See About Us for the full story and Contact to report an error — corrections are prioritised over all other work.
How Each Calculator Is Verified
This is a calculator site. Its job is to implement published formulas correctly and show you the working, not to tell you what to do — so the standard we hold ourselves to is verifiability rather than authority. Every claim on this page can be checked by someone who does not trust us.
| Check | What it means in practice |
|---|---|
| Formula provenance | Every equation comes from a named, published source — a guideline, a peer-reviewed paper, or a manufacturer’s prescribing information. The source is listed on the page that uses it. |
| Sources are linked | Where a free canonical URL exists, the citation links to it. Where it does not — textbooks, some product labelling — the reference is given in full so you can find it yourself. We do not link to a source we have not read. |
| Working is shown | Each result prints the arithmetic it used. If a number looks wrong, you can check it by hand rather than taking the tool’s word for it. |
| Arithmetic is machine-checked | Every worked example and reference table is re-computed from the underlying formula and compared against the published figure before the page ships. This has caught real errors in our own drafts. |
| Limits are stated | Each calculator carries a limitations section saying what it does not account for. A tool that hides its assumptions is harder to check, not easier to trust. |
| Guideline currency | Citations are checked against the current edition each January when the ADA publishes its Standards of Care, and updated across the site together. |
What we do not currently have: an independent clinician engaged to verify the calculators. We would rather say that plainly than imply a review that has not happened. Until one is in place, pages carry a “Last updated” date rather than a “Last reviewed” one, and the site makes no reviewedBy claim in its structured data. If you are a CDCES, RD, PharmD or physician willing to review this work, get in touch.
Found an error? Report it. Corrections take priority over every other kind of work on this site, and we will say what changed.
What These Tools Cannot Do
- They cannot individualise a dose. Population formulas are starting frameworks; real doses come from supervised titration.
- They cannot account for insulin on board, illness, activity, alcohol, pregnancy, renal function, or drug interactions unless the specific tool says so.
- They are not FDA-regulated medical devices and must not be used for autonomous dosing decisions.
Master Reference List
- American Diabetes Association. Standards of Care in Diabetes — 2026. Link
- Walsh J, Roberts R. Using Insulin: Everything You Need for Success with Insulin. Torrey Pines Press.
- Davidson PC, Hebblewhite HR, Steed RD, Bode BW. Analysis of guidelines for basal-bolus insulin dosing. Endocr Pract. 2008;14(9):1095-101.
- Matthews DR, et al. Homeostasis model assessment: insulin resistance and β-cell function. Diabetologia. 1985;28(7):412-9. Link
- Katz A, et al. Quantitative insulin sensitivity check index. J Clin Endocrinol Metab. 2000;85(7):2402-10. Link
- Bergenstal RM, et al. Glucose Management Indicator (GMI). Diabetes Care. 2018;41(11):2275-80. Link
- Nathan DM, et al. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008;31(8):1473-8. Link
- Pańkowska E, Błazik M. Bolus calculator with nutrition database software. J Diabetes Sci Technol. 2010.
- NIDDK. Insulin Medicines & Treatments. Link
Written by Ryan Mitchell · Last updated: September 2026