A practice tool that teaches the wrong answer is worse than none. This page sets out how every problem on NursingCalc is generated, where the numbers come from, how answers are marked, how the math is tested, and what happens when someone finds a mistake.
Problems are generated in your browser from realistic drug strengths and premixed bag concentrations, using the rounding rules nursing programs teach. Every problem type is tested by solving hundreds of thousands of generated problems a second, independent way. Problems are fictional exercises for learning, never a dosing reference. Errors can be reported from any problem and are corrected publicly.
It is a way to practice the arithmetic of medication administration: unit conversions, D/H × Q, rates, weight-based doses and drips. It is not a drug reference, a dosing calculator for patients, or a substitute for your program's teaching. Patients in the problems are fictional. Safe dose ranges in the pediatric problems are invented for the exercise, and those problems name no drug for that reason.
NursingCalc is run independently and does not claim clinical credentials. Accuracy comes from published sources, a documented method, and automated testing, all set out below.
Each problem type has its own generator. It picks a drug and strength from a fixed list, picks an order and patient values from realistic ranges, and keeps the problem only if the answer is clinically plausible: tablets between half and three, injections within what fits the route, pump rates and drip rates within what you would expect to see. Problems that would need an implausible answer are thrown away before you see them.
Every problem has an ID such as drip.S.48213: the type, the level (Easy, Standard or Hard) and a seed. The same ID always rebuilds the same problem, which is how an error report can be reproduced exactly.
| Premixed bag | Strengths used |
|---|---|
| Heparin in D5W | 20,000 units/500 mL; 25,000 units/500 mL; 25,000 units/250 mL |
| Dopamine in D5W | 400 mg/250 mL; 800 mg/250 mL |
| Dobutamine in D5W | 250, 500 and 1,000 mg/250 mL |
| Norepinephrine in NS | 4 mg/250 mL; 8 mg/250 mL |
| Nitroglycerin in D5W | 25 mg/250 mL; 50 mg/250 mL |
| Regular insulin in NS | 100 units/100 mL (premixed); 100 units/250 mL (labeled pharmacy-prepared) |
The premixed strengths above match current US prescribing information on DailyMed, checked in October 2026. Tablet, oral liquid and injection strengths are common US presentations; a sample of them was checked against DailyMed labels the same month. Where a tablet is only scored by some manufacturers, the problems avoid asking for half of it.
| Quantity | Default rule |
|---|---|
| Liquid volume over 1 mL | Nearest tenth |
| Liquid volume under 1 mL | Nearest hundredth |
| Tablets | Whole tablets; half only if scored (optional) |
| Drip rate (gtt/min) | Nearest whole drop |
| Pump rate (mL/hr) | Nearest tenth, or whole number (optional) |
| Weight converted to kg | Nearest tenth, or hundredth (optional) |
| BSA | Nearest hundredth |
| Heparin units | Nearest unit, or nearest 10 units (optional) |
| Infusion time | Nearest minute |
The defaults follow the rules most commonly published by nursing programs and open nursing textbooks. Half-up rounding is used throughout, only at the final step, and answers are shown with a leading zero below 1 and no trailing zeros, in line with ISMP's error-prone dose designations.
Rounding paths. Some calculations can be done two accepted ways, such as rounding a converted weight before using it or carrying it through. Where both are taught, both answers are accepted, and the worked solution shows the path it used.
Rounding errors. An answer that is mathematically right but rounded wrongly is marked wrong, with a note that the math was right. That matches how school exams mark.
Common mistakes. Each problem knows the answers produced by the classic slips: pounds used as kilograms, a daily dose not divided, hours instead of minutes, a missing × 60 or × 1,000, the diluent volume used instead of the concentration after mixing. If your answer matches one, the feedback names it.
Before any change goes live, an automated test generates 10,000 problems for each problem type at each level, plus a further set under alternate rounding settings: 468,000 problems in all. Each one is solved again by a separately written solver, and the test fails if the two disagree on any of them. The same run checks that answers fall in plausible ranges, that no text shows a trailing zero or a missing leading zero, that a common-mistake answer is never equal to a correct one, and that every problem ID rebuilds the same problem.
Every worked solution has a "Think this is wrong?" link. It opens an email to info@nursingcalc.com with the problem ID and the answers filled in, so the exact problem can be rebuilt. Reports are read within 48 hours. Confirmed errors are fixed within seven days and listed below.
| Date | Version | Change |
|---|---|---|
| October 2026 | Engine 1.0.2 | First release: 13 problem types, rounding settings, timed practice exam. |