Running balance on a controlled drug log, worked through
One 10 mL container at 10 mg/mL, five entries over four days, and a physical count at the end. The balance after each entry is the balance before it minus the volume taken out. Everything below is computed from those figures; edit them in the calculator to run 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) |
Runs in your browser; nothing you type is sent anywhere. Arithmetic for your records: we do not give legal or compliance advice.
Line by line
| Entry | Type | Before - volume (mL) | Balance (mL) |
|---|---|---|---|
| 1 | administered | 10 - 0.6 | 9.4 |
| 2 | waste | 9.4 - 0.1 | 9.3 |
| 3 | dispensed | 9.3 - 2.5 | 6.8 |
| 4 | administered | 6.8 - 1.2 | 5.6 |
| 5 | administered | 5.6 - 0.8 | 4.8 |
Totals
| Entry type | mL | mg at 10 mg/mL |
|---|---|---|
| Administered | 2.6 | 26 |
| Dispensed | 2.5 | 25 |
| Waste | 0.1 | 1 |
| All used | 5.2 | 52 |
| Computed ending balance | 4.8 | 48 |
The count
The count found 4.6 mL against a computed 4.8 mL, a difference of -0.2 mL (-2 mg). A gap this size often traces to a single entry: a transposed digit, an entry made twice, or one not made. Re-add the entries before anything else; the reconciliation walk-through shows how to work through it.
Questions
Should waste come off the running balance?
In this calculator, yes: waste is volume that left the container, so it is subtracted like any other entry and also totalled on its own line.
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.