Stay-length planning
Off-grid RV stay length calculator
Estimate whether power, solar recovery, fresh water, gray tank, or black tank capacity is most likely to end an off-grid stay first.
Cross-system calculator
Find the first thing that ends the stay.
Solar, battery, fresh water, gray tank, and black tank all get a vote. This tool compares them so you do not improve the wrong system first.
Power lane
Tank lane
Current result
This stay fits the entered margins
The weakest lane still reaches the 5-day target on paper. Keep a weather, water, and dump-station buffer before treating that as a guarantee.
Practical stay
5.0 days
Usable battery
2.2 kWh
Avg harvest
1.9 kWh/day
Open the water calculator next and test lower shower, dishwashing, cooking, and refill assumptions.
First limiter
Fresh water
5.0 days
40 gallons divided by 8 gallons/day for the whole crew.
Lower daily gallons, carry separate drinking water, add portable containers, or plan a refill before this day.
Limiter 2
Gray tank
7.0 days
35 gallons divided by 5 gallons/day from dishes, showers, and sink use.
Use basin dishwashing, shorter showers, outdoor rinse routines where legal, or schedule a dump stop sooner.
Limiter 3
Black tank
25.0 days
30 gallons divided by 1.2 gallons/day from toilet use and flush water.
Use less flush water, confirm tank capacity, or plan a dump stop before black tank margin gets uncomfortable.
Limiter 4
Power recovery
30.0 days
Average solar harvest covers the entered daily load on good-sun days, so power is not the first paper limiter.
Reduce daily watt-hours, add solar, add usable battery, or plan generator/alternator recovery before the bank gets low.
Shareable result
/tools/stay-length-calculator?v=1&people=2&target=5&usage=1800&ah=200&voltage=12&battery=lithium&solar=500&sun=5&fresh=40&gray=35&black=30&fpd=8&gpd=5&bpd=1.2
Prefilled stay-length scenarios
See which system ends the stay before upgrading the wrong one.
These scenarios compare power, solar recovery, fresh water, gray tank, and black tank limits for ordinary RV travel patterns.
Short trip baseline
Weekend Couple Starter
Best first pass when you need to know which system ends the trip first.
Load this profileWorkday-capable profile
Remote Work Desert Week
Best first pass when you need to know which system ends the trip first.
Load this profileLower-sun profile
Shoulder-Season Forest Camp
Best first pass when you need to know which system ends the trip first.
Load this profileMore people, faster tanks
Family Dry-Camping Long Weekend
Best first pass when you need to know which system ends the trip first.
Load this profileLean system profile
Minimal Van or Small Trailer
Best first pass when you need to know which system ends the trip first.
Load this profileWant the reusable trip-readiness version?
Off-Grid Readiness Binder
A printable binder asset for departure checks, tank planning, camp setup, reset-day routines, and seasonal prep before the trip starts.
Delivered as printable PDFs plus a tablet-friendly planning copy. Use the contact flow for asset access, bundle questions, or a custom version.
What it adds
$39A working trip binder for the garage or tow vehicle
Cleaner handoffs between driver, setup, and indoor tasks
Less forgotten friction before departure day
Better continuity from one trip to the next
Inside at a glance
Departure, setup, reset-day, and shutdown checklists grouped by system
Tank, propane, and refill planning sheets that can be reused trip after trip
Seasonal inserts for heat, wind, shoulder season, and cold snaps
What this adds
The separate calculators size the parts. This one ranks the bottlenecks.
A stay-length estimate is useful when you are deciding what to improve next. If the gray tank is the first limiter, buying another battery is solving the wrong problem.
Tune the power lane
Use this when power recovery or battery reserve is the shortest lane.
Open next stepTune the water lane
Use this when fresh water, gray water, or daily habits are the shortest lane.
Open next stepRead the stay-length guide
Use the guide when you need rules, land access, resupply, and practical trip pacing.
Open next stepLimiter map
A longer stay usually fails in one of four lanes.
Compare fast
| Spec | What it means | Best next move |
|---|---|---|
| Power recovery | Daily load is outrunning average solar harvest and usable battery reserve. | Reduce Wh/day, add solar, add battery, or plan generator/alternator recovery. |
| Fresh water | The crew's gallons/day burns through the fresh tank before the target stay ends. | Use the water calculator, carry separate drinking reserve, or plan a refill. |
| Gray tank | Sink, shower, and dishwater capacity ends the stay before fresh water does. | Change dishwashing and shower routines or plan a dump stop sooner. |
| Black tank | Toilet use and flush water create the first waste-capacity limit. | Confirm tank size, adjust flush habits, or shorten the dump interval. |
Stay-length math
How the stay-length calculator ranks the bottlenecks
The tool compares usable battery reserve after solar harvest, fresh-water burn rate, gray tank fill rate, and black tank fill rate. The shortest lane is the one to fix first.
Power days
Usable battery watt-hours are compared against the daily power gap after average solar harvest. If solar covers the daily load on good-sun days, power is not treated as the first paper limiter.
Water days
Fresh tank days are tank gallons divided by total daily gallons for the crew. This keeps the estimate tied to actual habits instead of a generic per-person number.
Waste days
Gray and black tank days are calculated separately because either tank can end a stay before fresh water or battery reserve does.
Avoid these traps
Common mistakes before buying
Improving the wrong lane first
Adding solar does not help if gray tank capacity ends the trip on day four. This calculator ranks the limiting systems before you spend money.
Using best-case solar as a guarantee
Good-sun harvest is an average planning number, not a weather promise. Shade, dust, heat, clouds, and campsite orientation can all move the power result.
Ignoring legal stay limits
A rig may be able to stay ten days on paper, but land-manager rules, road conditions, water source closures, and dump access still control the real plan.
Treat the calculator result as a planning range, then verify wiring, clearances, fusing, ventilation, and manufacturer limits before installation.See assumptions
Frequently asked
Questions RVers usually ask next.
Is this a replacement for the solar, battery, and water calculators?
No. Use this calculator to find the first limiter. Then open the detailed calculator for that lane and tune the assumptions before buying gear.
Why does the calculator include gray and black tanks?
Waste capacity is often the overlooked stay-length limit. A fresh tank can look fine while gray water or black water forces a dump stop first.
What should I do if power is the first limiter?
Check the daily watt-hour estimate first. If the load is real, compare adding solar, adding battery, reducing inverter use, or planning generator/alternator recovery.
What safety margin should I keep?
Keep at least one day of drinking water separate from normal wash water, and avoid planning battery discharge down to the edge. Treat this result as a planning range, not a guarantee.