U-500 Insulin Dose and Supply Calculator
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — October 2026
Split a Humulin R U-500 daily dose into KwikPen doses in 5-unit steps and plan how many pens a 30 or 90 day supply needs. Educational use only.
💉 U-500 Dose & Supply Calculator
U-500 KwikPen Plan
units (5-unit steps)
mL
(2 pens each)
What U-500 insulin is
Humulin R U-500 is concentrated regular human insulin: 500 units in every mL, five times the strength of standard U-100 insulin. It is prescribed for people who need more than 200 units of insulin a day, usually because of severe insulin resistance. At that dose, U-100 insulin means large, uncomfortable injection volumes; U-500 delivers the same units in one-fifth of the volume.
| Feature | Humulin R U-500 KwikPen |
|---|---|
| Concentration | 500 units per mL |
| Pen contents | 3 mL = 1,500 units |
| Dose steps | 5 units |
| Largest single injection | 300 units |
| After first use at room temperature | 28 days |
| Onset and duration | Under 15 minutes; about 21 hours (13–24 hours) |
| Usual schedule | 2–3 times daily, about 30 minutes before meals |
Because its action lasts most of the day, U-500 covers both background and mealtime needs. The prescribing information notes that its safety and effectiveness alongside other insulins, or in an insulin pump, have not been determined.
Splitting large insulin doses is the other common approach. A single injection much above about 100 units becomes uncomfortable on a 1 mL U-100 syringe, so prescribers often split it into two injections — which changes the timing of the dose and should be agreed with the prescriber. When daily requirements climb far higher, U-500 exists precisely to shrink the volume: the same 300 units takes 0.6 mL instead of 3 mL.
No unit conversion with the KwikPen
The KwikPen dial shows the actual number of U-500 units delivered. If the prescription is 150 units, dial 150. Do not convert the dose into a volume or into U-100 units. The volume figures on this page are for supply planning only. To see how concentration changes volume in general, use the insulin units to mL calculator.
Never draw U-500 insulin out of the pen with a syringe. A standard U-100 syringe marks units of U-100 insulin, so a dose drawn to its 20-unit mark would contain 100 units of U-500. The prescribing information warns that transferring U-500 into a syringe can cause overdose and severe hypoglycemia.
How many U-500 pens you need
Each pen holds 1,500 units, so divide the units used over the supply period by 1,500 and round up. For example, 250 units a day for 30 days is 7,500 units, or 15 mL, which needs 5 pens. Priming doses add to that total, so include them if your Instructions for Use require a priming step before each injection. For U-100 pens, the pens per month calculator works the same way.
| Daily dose | Volume per day | 30-day supply | 90-day supply |
|---|---|---|---|
| 200 units | 0.40 mL | 4 pens (2 cartons) | 12 pens (6 cartons) |
| 250 units | 0.50 mL | 5 pens (3 cartons) | 15 pens (8 cartons) |
| 300 units | 0.60 mL | 6 pens (3 cartons) | 18 pens (9 cartons) |
| 400 units | 0.80 mL | 8 pens (4 cartons) | 24 pens (12 cartons) |
| 500 units | 1.00 mL | 10 pens (5 cartons) | 30 pens (15 cartons) |
| 600 units | 1.20 mL | 12 pens (6 cartons) | 36 pens (18 cartons) |
Pens are sold two to a carton. The figures exclude priming and assume each pen is used within its 28-day limit, which holds for any dose above 200 units a day.
Switching from U-100 to U-500
The daily dose in units is the starting point. Add up the total daily insulin, for which the total daily dose calculator helps, then split it into two or three injections before meals. Published U-500 dosing guidance commonly uses 60% before breakfast and 40% before the evening meal for twice-daily dosing, or 40%, 30% and 30% for three doses. Some prescribers reduce the total by 10–20% at the switch when glucose is already near target or lows have occurred.
The first weeks need close glucose monitoring. U-500's long action means a low can last for hours, so any reduction or delay in meals deserves attention. In-use limits also apply: discard a pen 28 days after it goes to room temperature, as the insulin expiration date calculator shows. U-100 dosing tools are grouped in our standard insulin dose calculators.
U-500 Insulin Calculator: Limitations & Safety Notes
- U-500 is only for people who need more than 200 units of insulin a day, and only on prescription.
- The calculator rounds each dose to the pen's 5-unit steps. Your prescription sets the actual doses.
- The pen delivers at most 300 units per injection. A larger dose must be split, as your prescriber directs.
- Do not mix U-500 with other insulin, dilute it or inject it into a vein.
- Never share a pen between people, even with a new needle.
Frequently Asked Questions: U-500 Insulin
Who needs U-500 insulin?
Humulin R U-500 is prescribed for adults and children who need more than 200 units of insulin a day. It delivers the same units as U-100 insulin in one-fifth of the volume, which makes large doses easier to inject.
How many units are in a U-500 KwikPen?
Each 3 mL KwikPen contains 1,500 units. The pen dials in 5-unit steps and gives up to 300 units in one injection.
How many U-500 pens do I need for a month?
Divide the units used in a month by 1,500 and round up. At 250 units a day, 30 days uses 7,500 units, which is 5 pens. Add any priming doses your Instructions for Use require.
Can I use a regular insulin syringe with U-500?
No. Never draw U-500 out of the KwikPen with a syringe. A U-100 syringe is marked for U-100 insulin, so a dose measured with it would contain five times the intended insulin.
How long does an opened U-500 pen last?
A Humulin R U-500 KwikPen kept at room temperature must be discarded after 28 days. That count includes any time the pen spent unopened at room temperature, as well as time in use.
Sources
- Eli Lilly and Company. Humulin R U-500 (insulin human injection) prescribing information. Link
- Cambridge University Hospitals NHS Foundation Trust. Humulin R U500 insulin (500 units/ml): patient information. Link
- American Diabetes Association. Standards of Care in Diabetes — 2026. Section 9. Diabetes Care. 2026;49(Suppl 1). Link
Written by Ryan Mitchell · Last updated: October 2026