Insulin Dose Calculator

Calculate mealtime insulin from a prescribed carbohydrate ratio and correction factor.

About Insulin Dose Calculator

The bolus combines a meal component from the carbohydrate ratio and a correction component from the glucose excess. Deducting active insulin prevents stacking, which is a common cause of hypoglycaemia. Ratios and correction factors are individual, change over time and differ by time of day, so they must come from the prescriber rather than from any general rule.

Formula

Insulin Dose

Bolus = carbohydrate ÷ carb ratio + (glucose − target) ÷ correction factor − active insulin

carbohydrate ratio: Grams of carbohydrate covered by one unit, set by the prescriber
insulin on board: Insulin from a previous dose still acting, deducted to avoid stacking

Worked example

With the default values below, Insulin Dose Calculator returns Total Calculated Bolus of 6.90. Change any input above and every figure here is recalculated in your browser.

Inputs used

Carbohydrate in the mealminimum 0 g: 60 g
Prescribed carbohydrate ratiominimum 0.1 g/unit: 10 g/unit
Current blood glucoseminimum 0 mmol/L: 9.5 mmol/L
Prescribed target glucoseminimum 0.1 mmol/L: 6 mmol/L
Prescribed correction factorminimum 0.1 mmol/unit: 2.5 mmol/unit
Active insulin on boardminimum 0 units: 0.5 units

Results

Total Calculated Bolus: 6.90 units
Meal Component: 6.00 units
Correction Component: 1.40 units
Glucose Above Target: 3.50 mmol/L
Deduction for Active Insulin: 0.50 units

Step by step

1Values used
2Insulin Dose
3Total Calculated Bolus= 6.90 units
4Meal Component= 6.00 units
5Correction Component= 1.40 units
6Glucose Above Target= 3.50 mmol/L
7Deduction for Active Insulin= 0.50 units

Assumptions and limits

The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
This performs arithmetic on figures you supply and does not recommend any drug, dose or route. Medication errors can cause serious harm or death. Always verify every calculation independently, confirm against the prescription and product literature, and follow your institution's double-check procedures. Never self-medicate or alter a prescribed dose. Insulin is a high-risk medicine and dosing errors can be fatal. Use only the ratios and factors prescribed for you by your diabetes team, follow their guidance on hypoglycaemia and illness, and contact them before changing any setting. This tool does not replace your prescribed regimen or your device.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

This performs arithmetic on figures you supply and does not recommend any drug, dose or route. Medication errors can cause serious harm or death. Always verify every calculation independently, confirm against the prescription and product literature, and follow your institution's double-check procedures. Never self-medicate or alter a prescribed dose. Insulin is a high-risk medicine and dosing errors can be fatal. Use only the ratios and factors prescribed for you by your diabetes team, follow their guidance on hypoglycaemia and illness, and contact them before changing any setting. This tool does not replace your prescribed regimen or your device.

Frequently Asked Questions

How is Insulin Dose calculated?

Bolus = carbohydrate ÷ carb ratio + (glucose − target) ÷ correction factor − active insulin The bolus combines a meal component from the carbohydrate ratio and a correction component from the glucose excess. Deducting active insulin prevents stacking, which is a common cause of hypoglycaemia.

Why does Insulin Dose matter?

Ratios and correction factors are individual, change over time and differ by time of day, so they must come from the prescriber rather than from any general rule.

What values do I need to enter?

This calculator takes 6 inputs: Carbohydrate in the meal, Prescribed carbohydrate ratio, Current blood glucose, Prescribed target glucose, Prescribed correction factor, Active insulin on board. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.