# IV Drip Rate Calculator

> Converts an infusion volume and duration into a gravity drip rate in drops per minute for a given tubing drop factor, and the equivalent pump rate in mL per hour.

- Calculator id: `iv-drip-rate` · Category: Medical & Clinical (`medical`) · Tool name: `calculate_iv_drip_rate`
- Canonical page: https://tttkmbb.com/medical/iv-drip-rate · This document: https://tttkmbb.com/medical/iv-drip-rate.md · JSON definition: https://tttkmbb.com/medical/iv-drip-rate.json

## Purpose

Converts an infusion volume and duration into a gravity drip rate in drops per minute for a given tubing drop factor, and the equivalent pump rate in mL per hour.

**Use when:** You need to set a gravity infusion (macrodrip 10, 15 or 20 gtt/mL, microdrip 60 gtt/mL) or an infusion pump for a given volume over a given time.

**Do not use when:** The medication needs a weight-based dose first (use dose-by-weight) or the infusion is controlled by a syringe driver in mL/h with a dose-rate unit.

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `volume_ml` | number | mL | required | Total volume of the infusion. (> 0, max 20000) |
| `duration_minutes` | number | min | required | Time over which the volume is to run (hours × 60). (> 0, max 10080) |
| `drop_factor_gtt_per_ml` | number | gtt/mL | optional, default 20 | Drops per mL printed on the giving set: 10, 15 or 20 for macrodrip, 60 for microdrip. (min 1, max 100) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `drops_per_minute` | number | gtt/min | volume × drop factor / minutes. |
| `drops_per_minute_rounded` | integer | gtt/min | Nearest whole drop per minute, as set at the bedside. |
| `ml_per_hour` | number | mL/h | volume / hours. |
| `seconds_per_drop` | number | s | 60 / drops per minute. |
| `duration_hours` | number | h | Infusion time in hours. |

## Formula

`drops_per_minute = volume_ml × drop_factor_gtt_per_ml / duration_minutes; ml_per_hour = volume_ml / (duration_minutes / 60)`

Gravity drip rates are approximate: drop size varies with fluid viscosity and set design, and the rate must be rechecked as bag height and venous pressure change. Results are informational only and not a substitute for clinical judgement or medical advice.

## Data Sources

- Craker M, Janke C (2024) Nursing Dosage Calculations (open textbook, WisTech Open) — https://wtcs.pressbooks.pub/nursingdosagecalculations/ (textbook, retrieved 2026-09-24)
- Wikipedia – Drop (unit): IV drop factors — https://en.wikipedia.org/wiki/Drop_(unit) (reference, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/iv-drip-rate?volume_ml=…&duration_minutes=…`
- `POST https://tttkmbb.com/api/v1/calculate/iv-drip-rate` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/iv-drip-rate · OpenAPI operationId `calculate_iv_drip_rate` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "iv-drip-rate", "inputs": {…}}`

## Example

- 1000 mL over 8 h, 20 gtt/mL: inputs `{"volume_ml":1000,"duration_minutes":480,"drop_factor_gtt_per_ml":20}` → `{"drops_per_minute":41.7,"drops_per_minute_rounded":42,"ml_per_hour":125,"duration_hours":8}`
- 100 mL over 30 min, microdrip 60 gtt/mL: inputs `{"volume_ml":100,"duration_minutes":30,"drop_factor_gtt_per_ml":60}` → `{"drops_per_minute":200,"ml_per_hour":200,"seconds_per_drop":0.3}`

```
GET https://tttkmbb.com/api/v1/calculate/iv-drip-rate?volume_ml=1000&duration_minutes=480&drop_factor_gtt_per_ml=20
```

## Limitations

The medication needs a weight-based dose first (use dose-by-weight) or the infusion is controlled by a syringe driver in mL/h with a dose-rate unit. Gravity drip rates are approximate: drop size varies with fluid viscosity and set design, and the rate must be rechecked as bag height and venous pressure change. Results are informational only and not a substitute for clinical judgement or medical advice. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Why does microdrip give the same number as mL/h?**

With 60 gtt/mL, drops per minute equal mL per hour (60 drops/mL × mL/h ÷ 60 min/h), which is why microdrip sets are used for precise low-volume infusions.

**Should I round the drip rate?**

Yes, to the nearest whole drop per minute; count drops for a full minute (or 15 s × 4) when setting the roller clamp.

## Related

- [Dose by Weight Calculator](https://tttkmbb.com/medical/dose-by-weight.md) — Calculate the dose and volume before setting the rate.
- [Maintenance Fluids Calculator](https://tttkmbb.com/medical/maintenance-fluids.md) — Hourly maintenance volumes to infuse.