Insulin Correction Dose Calculator
Estimate a correction (supplemental) dose of rapid-acting insulin for a high blood glucose. Enter the current glucose, the target, and the correction factor — how many mg/dL one unit of insulin is expected to lower the glucose — to get the correction dose. This covers the correction component only, not basal or mealtime (nutritional) insulin, and the correction factor must come from the patient’s own regimen.
About correction insulin
A correction dose brings a high glucose back toward target using the individual’s insulin sensitivity, and normally sits on top of scheduled basal and mealtime insulin rather than replacing them. Because insulin is a high-alert medication, the correction factor and target come from the prescribed plan. This is an educational reference, not medical advice.
Frequently asked questions
How is a correction insulin dose calculated?
Correction dose (units) = (current glucose − target glucose) ÷ correction factor. The correction factor (also called the insulin sensitivity factor) is how many mg/dL one unit of rapid-acting insulin is expected to lower the glucose. For example, with a current glucose of 250, a target of 120 and a correction factor of 50, the dose is (250 − 120) ÷ 50 = 2.6, which rounds to about 3 units. If the glucose is at or below target, no correction is given.
Where does the correction factor come from?
It is individual and set by the prescriber. A common starting estimate is the “1800 rule” for rapid-acting insulin: correction factor ≈ 1800 ÷ total daily dose (TDD) of insulin. So someone on 45 units a day has a correction factor around 40 mg/dL per unit. The “1500 rule” (1500 ÷ TDD) is sometimes used for regular insulin. These are only starting points and are refined against real glucose responses — enter the value from the patient’s regimen rather than assuming.
What is the difference from a fixed sliding scale?
A traditional sliding scale gives preset insulin amounts for glucose ranges, the same for everyone. A correction dose based on a personal correction factor and target is more individualised and is preferred, usually added on top of scheduled basal and mealtime insulin. Correction-only (sliding-scale-alone) regimens are discouraged for ongoing inpatient care because they treat highs reactively without preventing them.
How is the risk of hypoglycaemia managed?
Stacking correction doses too close together — before the previous rapid-acting dose has finished working (about 3–4 hours) — is a common cause of hypoglycaemia. Correction doses are usually reduced or held overnight, and adjusted for reduced intake, kidney impairment or a history of lows. The dose from any calculator is a starting estimate that must fit the whole regimen and the clinical situation.
Is this calculator safe to dose from directly?
It is an educational reference, not medical advice, and not a substitute for a prescribed insulin plan. Insulin is a high-alert medication; doses should follow the individual’s prescription and, in hospital, local protocols and independent double-checks. Confirm any dose with the treating team.
This is a reference tool, not a diagnosis or medical advice. Results depend on the laboratory, assay and clinical context, and reference intervals vary between labs and by age and sex — always read your result against the range printed on your own report and discuss it with a qualified healthcare professional.
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