⏱️ Tank Runtime Calculator
Runtime
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Enter tank size and flow rate above
Common Flow Rates by Application
| Application | Typical Flow Rate | Notes |
|---|---|---|
| Garden drip irrigation | 0.5–2 GPM | Depends on emitter count and layout |
| Residential sprinkler zone | 3–8 GPM | Per zone; varies by head type |
| Electric pressure washer | 1.2–2 GPM | 1,500–2,000 PSI range |
| Gas pressure washer | 2–4 GPM | 2,000–4,000 PSI range |
| 12V demand pump (RV / detail rig) | 3–5 GPM | At 40–60 PSI |
| Livestock float valve (auto-refill) | 2–5 GPM | Intermittent; not continuous |
| Fire hose (1.5" line) | 60–100 GPM | Rural fire suppression |
| Center pivot irrigation | 400–900 GPM | Typically fed direct from well |
Runtime Reference Table
| Tank Size | @ 2 GPM | @ 4 GPM | @ 8 GPM | @ 20 GPM |
|---|---|---|---|---|
| 100 gallons | 50 min | 25 min | 12.5 min | 5 min |
| 250 gallons | 2h 5m | 1h 2m | 31 min | 12.5 min |
| 500 gallons | 4h 10m | 2h 5m | 1h 2m | 25 min |
| 1,000 gallons | 8h 20m | 4h 10m | 2h 5m | 50 min |
| 2,500 gallons | 20h 50m | 10h 25m | 5h 12m | 2h 5m |
| 5,000 gallons | 41h 40m | 20h 50m | 10h 25m | 4h 10m |
The Formula
💡 Runtime Formula
| Runtime (minutes) | Gallons ÷ GPM |
| Runtime (hours) | Gallons ÷ GPM ÷ 60 |
| Required tank size | GPM × Runtime (minutes) |
Sizing a Tank to a Runtime Target
If you know how long you need to run and your flow rate, work backward: multiply GPM × target runtime in minutes = gallons needed. A pressure washing business that runs 3 GPM for 4 hours (240 minutes) needs 3 × 240 = 720 gallons of tank capacity per fill.