Warsaw Method Calculator (FPU)
Estimate the extended insulin bolus for the fat and protein in a meal with the Warsaw method: convert fat and protein into fat-protein units (FPU), get the carbohydrate equivalent, the bolus dose (using your insulin-to-carb ratio) and the square-wave bolus duration. Free, private (runs 100% in your browser), no sign-up.
Calculate the extended bolus
Enter the fat and protein in your meal plus the insulin-to-carb ratio you use for your normal bolus. All fields are required.
Your Warsaw method estimate
Extended (square-wave) bolus for the fat and protein in this meal — in addition to your normal carbohydrate bolus.
Fat-protein units
Carbohydrate equivalent
Extended bolus dose
Bolus duration
How to read your result
The extended bolus is a square-wave bolus on your pump: it delivers the dose spread evenly over the shown duration, matching the delayed glucose rise that fat and protein cause. Your meal carbohydrate is still dosed separately as a normal (immediate) bolus.
| FPUs in the meal | Extended bolus runs over | Example |
|---|---|---|
| 1 | 3 hours | 100 kcal from fat + protein |
| 2 | 4 hours | 200 kcal from fat + protein |
| 3 | 5 hours | 300 kcal from fat + protein |
| 4 or more | 8 hours | 400+ kcal from fat + protein |
Fractional FPU values are rounded to the nearest whole unit for the duration (e.g. 1.7 FPU → 4 hours); below 0.5 FPU the method defines no extended bolus. 1 FPU roughly corresponds to the insulin need of 10 g of carbohydrate, dosed with your usual insulin-to-carb ratio.
The formula (for transparency)
Exactly the published Warsaw method — no hidden adjustments.
fat_kcal = fat_g × 9
protein_kcal = protein_g × 4
total_kcal = fat_kcal + protein_kcal
FPU = total_kcal / 100 (1 FPU = 100 kcal)
carb_equiv (g) = total_kcal / 10 (1 FPU ≈ 10 g carbs)
extended_dose (u) = carb_equiv / ICR (ICR = insulin-to-carb ratio)
bolus duration: 1 FPU → 3 h | 2 FPU → 4 h | 3 FPU → 5 h | ≥ 4 FPU → 8 h
(fractional FPU rounded to nearest whole for the duration;
below 0.5 FPU → no extended bolus)Worked example
Meal with 20 g fat and 30 g protein, insulin-to-carb ratio 10 g/unit: fat kcal = 20 × 9 = 180; protein kcal = 30 × 4 = 120; total = 300 kcal; FPU = 300 / 100 = 3; carb equivalent = 300 / 10 = 30 g; extended dose = 30 / 10 = 3 units delivered as a square-wave bolus over 5 hours.
Sources
- Pankowska E, Błazik M. Bolus calculator with nutrition database software, a new concept of prandial insulin programming for pump users. Pediatric Diabetes. 2009;10(5):298-303. (derivation — Warsaw Pump Therapy School)
- Pepe C et al. Review of the Warsaw method: 1 FPU = 100 kcal from fat/protein ≈ 10 g carbohydrate; square-wave bolus durations of 3 h for 1 FPU, 4 h for 2 FPU, 5 h for 3 FPU and 8 h for 4+ FPU. Journal of the Endocrine Society. 2017. (primary-source spot check for all constants)
- OmniCalculator — Warsaw method calculator: worked examples cross-checked (10 g fat + 20 g protein → 170 kcal → FPU 1.7; 200 kcal → 2 FPU → 4 h bolus).
- onlycalculators.com — Warsaw method calculator: worked example cross-checked (300 kcal → FPU 3 → 30 g carb equivalent → 3 units at ICR 10 → 5 h bolus).
Frequently asked questions
What is the Warsaw method?
The Warsaw method is an insulin-dosing protocol for type 1 diabetes developed by the Warsaw Pump Therapy School (Pankowska et al., Pediatric Diabetes 2009). It addresses the delayed blood-glucose rise caused by fat and protein in a meal — something standard carbohydrate counting misses. Carbohydrate is covered with a normal bolus using the usual insulin-to-carb ratio, while the fat and protein content is converted into fat-protein units (FPU) and covered with an additional extended (square-wave) insulin bolus whose dose and duration depend on the number of FPUs.
What is an FPU (fat-protein unit)?
One fat-protein unit (FPU) equals 100 kilocalories of energy from fat and protein combined, calculated as: fat kcal = fat (g) × 9, protein kcal = protein (g) × 4, total kcal = fat kcal + protein kcal, FPU = total kcal / 100. According to the Warsaw method, 1 FPU roughly corresponds to an insulin requirement equivalent to about 10 grams of ingested carbohydrate, and it is dosed using the same insulin-to-carb ratio as the carbohydrate bolus.
How is the carbohydrate equivalent of fat and protein calculated?
The Warsaw method converts the energy from fat and protein into a carbohydrate equivalent: total kcal from fat and protein divided by 10. For example, a meal with 20 g of fat (180 kcal) and 30 g of protein (120 kcal) totals 300 kcal, which equals a carbohydrate equivalent of 30 g. Dividing that 30 g by your insulin-to-carb ratio gives the extended bolus dose — for example, 3 units at a ratio of 10 g per unit.
How is the extended bolus insulin dose calculated?
Extended bolus dose (units) = carbohydrate equivalent (g) ÷ insulin-to-carb ratio (g per unit). The Warsaw method uses the same insulin-to-carb ratio you use for your normal carbohydrate bolus. Because the dose is an additional insulin amount on top of your carbohydrate bolus, always confirm the final dose with your diabetes care team before changing your regimen.
How long should the extended bolus run?
The published Warsaw chart sets the square-wave bolus duration from the number of fat-protein units: 1 FPU over 3 hours, 2 FPU over 4 hours, 3 FPU over 5 hours, and 4 or more FPU over 8 hours. The long duration matches the delayed, prolonged blood-glucose rise that fat and protein cause after a meal.
What does this calculator do with fractional FPU values?
The published Warsaw bolus-duration chart is defined per whole FPU, so this calculator rounds your FPU to the nearest whole number for the duration: for example, 1.7 FPU is treated as 2 FPU and runs over 4 hours. A meal below 0.5 FPU (less than about 50 kcal from fat and protein) shows no extended bolus, since the chart does not cover that range. FPU of 4 or more always uses the 8-hour duration.
Does the Warsaw method replace my normal carbohydrate bolus?
No. In the Warsaw method the carbohydrate in a meal is still dosed as a normal (immediate) bolus using the usual insulin-to-carb ratio. The FPU calculation adds a second, extended bolus on top of that to cover the additional glucose effect of fat and protein. This calculator computes only the FPU portion — you still need to count and dose your meal carbohydrate separately.
Can I use the Warsaw method without an insulin pump?
The Warsaw method was designed for insulin pump therapy, because only a pump can deliver the square-wave (extended) bolus over several hours. People using multiple daily injections cannot easily replicate an extended bolus and would need a different dosing strategy agreed with their diabetes care team. This calculator assumes pump use.
Is the Warsaw method right for my diabetes management?
The method is intended for people with type 1 diabetes on intensive insulin pump therapy who experience delayed glucose rises after high-fat, high-protein meals (for example pizza or fast food). It is an advanced technique: dosing for fat and protein increases the risk of hypoglycemia if misapplied, and studies have found mixed results in adults. Do not adopt it on your own — discuss whether it is appropriate for you with your endocrinologist or diabetes educator first.
What are the limitations of this Warsaw method calculator?
It performs only the arithmetic of the published method: calories from fat and protein, FPU, carbohydrate equivalent, dose and the chart-based duration. It cannot account for your personal insulin sensitivity, current blood glucose, insulin on board, exercise, illness, alcohol or stress — all of which change your real insulin needs. The outputs are educational estimates, not dosing instructions. Never change your insulin dosing based on this tool without consulting your diabetes care team.
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