Controlled substance log calculator
Enter one container: its concentration and the volume it started with. Add each entry from the log. The table keeps a running balance in mL and mg, totals each kind of entry, and, if you type a counted balance, shows the difference from the computed one. It is prefilled with a five-entry example; replace it with your own.
Entries
Paste entries instead
| # | Date | Entry | Patient / ref | Change (mL) | Balance (mL) | Balance (mg) |
|---|---|---|---|---|---|---|
| Starting balance | 10 | 100 | ||||
| 1 | 2026-10-01 | Administered | Patient 1041 | -0.6 | 9.4 | 94 |
| 2 | 2026-10-01 | Waste | Patient 1041, witnessed | -0.1 | 9.3 | 93 |
| 3 | 2026-10-02 | Dispensed | Rx 2207 | -2.5 | 6.8 | 68 |
| 4 | 2026-10-03 | Administered | Patient 1058 | -1.2 | 5.6 | 56 |
| 5 | 2026-10-04 | Administered | Patient 1063 | -0.8 | 4.8 | 48 |
| Container | Example drug, 10 mL vial #1, 10 mg/mL |
| Starting balance | 10 mL (100 mg) |
| Dispensed | 2.5 mL |
| Administered | 2.6 mL |
| Waste | 0.1 mL |
| Adjustments (net) | 0 mL |
| Total used (dispensed + administered + waste) | 5.2 mL (52 mg) |
| Computed ending balance | 4.8 mL (48 mg) |
| Counted balance | 4.6 mL (46 mg) |
| Counted minus computed | -0.2 mL (-2 mg) |
5 mg = 0.5 mL at 10 mg/mL
Runs in your browser; nothing you type is sent anywhere. Arithmetic for your records: we do not give legal or compliance advice.
How the balance is worked out
Each dispensed, administered or waste entry takes its volume out of the container. An adjustment is signed: type +0.5 to add volume, -0.5 to take it out. The balance after each entry is the one before it plus that change. In the example the container started at 10 mL and the entries total 5.2 mL, leaving 4.8 mL (48 mg at 10 mg/mL).
Counted balance
If you measure what is left and type it in, the calculator subtracts the computed balance from it. Zero means the two agree. Any other figure is the size of the gap, in mL and mg, with its sign: negative means the container holds less than the entries say. What that gap means for your practice is for you to work out; the reconciliation walk-through shows the arithmetic for tracing it.
Pasting from a spreadsheet
Paste rows as date, type, mL, patient or reference, one per line.
Tab-separated rows copied from a spreadsheet work too. The type is matched on its first three letters: dis, adm, was or
adj. Nothing you type or paste leaves your browser.
Questions
What does the calculator do with the drug name?
It only labels the summary. The arithmetic uses the concentration and the volumes.
Why mL and mg?
Logs are usually kept in the unit you draw up. The mg figure is the mL figure times the concentration you entered, shown so both read the same.
Does this tell me whether my log is compliant?
No. We keep and total your records; we do not give legal or compliance advice. The calculator adds and subtracts the figures you type and shows where two of them differ.