Meet DryDays — Off-grid days left, per tank

Travel

DryDays

Off-grid days left, per tank

What DryDays does

Somewhere on night three of every boondocking trip, the same argument starts: how many days do we actually have left? The fresh tank gauge says half. The black tank has read two-thirds since the day you bought the rig. The gray tank — the one that always fills first — doesn't get a vote until it backs up into the shower pan. Factory tank sensors are notoriously unreliable, so experienced dry campers ignore them and guess from memory, or spend a hundred dollars per tank on aftermarket hardware that still never answers the actual question.

DryDays answers it. Set up your rig once — fresh, gray, and black tank capacities, propane bottles, and battery bank — then log the moments that matter: a full fill at the spigot, a dump station stop, a quick morning level check. From those few taps, DryDays computes a live countdown for every resource: fresh 3.5 days, gray 2.1 days, propane 9 days, battery fine. It names your binding constraint in plain words — gray water is what ends this trip — so you know exactly when you have to break camp. Not roughly. Not hopefully.

The more you camp, the smarter it gets. DryDays learns your household's real consumption — your gallons per day and amp-hours per day, with the grandkids along and without — from your own trip history instead of the generic assumptions every one-shot web calculator uses. Before the next trip, plan against those learned rates: ten days at the lake with four people means the gray tank is your limit on day six unless you shower at the beach.

Battery math is handled properly too. Tell DryDays whether you run lead-acid or lithium and it applies the right usable-depth rule, so 200 amp-hours means what it actually means for your bank.

And because the whole point is camping where there is no signal, everything works completely offline. No account, no cloud, no subscription — your rig, your history, and your countdown live on your phone at the end of a dirt road, exactly where the websites and calculators stop working.

• Live days-remaining countdown for fresh, gray, black, propane, and battery • Names the binding constraint that will end your trip first • One-tap logging of fills, dumps, and daily level checks • Learns your real gallons-per-day and amp-hours-per-day from trip history • Pre-trip planner that budgets water and power against your learned rates • Lead-acid and lithium battery modeling with correct usable capacity • 100% offline, no account, no subscription

A look inside

Tap any screenshot to open the full-resolution version.

What's inside

• Rig Setup — Enter your rig once: fresh, gray, and black tank capacities in gallons, propane bottles in pounds, and battery bank in amp-hours with chemistry (lead-acid or lithium). Everything downstream keys off these numbers.
• Countdown Dashboard — The home screen every boondocker checks with coffee: five playful gauge cards showing days remaining per resource, with the binding constraint called out in plain words at the top — gray water ends this trip in 2.1 days.
• Event Log — One-tap logging of the moments that matter: full fill, dump station stop, propane swap, morning level check. Each entry updates the countdown instantly, fully offline.
• Trip History & Rates — Trips group your entries and become your calibration data: DryDays derives your household's real gallons-per-day and amp-hours-per-day per trip, then trends them across trips and party sizes.
• Battery Modeler — Applies the correct usable-depth rule to your bank — 50% for lead-acid, deeper for lithium — and folds daily amp-hour draw into the same days-remaining countdown as the tanks.
• Pre-Trip Planner — Budget the next trip before you leave: days, party size, and your learned rates produce a per-resource forecast and a packing verdict — you will hit gray capacity on day six — exportable as a trip report PDF.

Why we built it

Off-grid campers can't answer the only question that matters — how many days do we have left — because factory tank sensors are notoriously wrong (crud-fouled floats, black tanks reading 2/3 forever), so they guess from experience, buy $70-110 sensor hardware per tank, or keep spreadsheets of gallons and amp-hours tha…

What makes it different

SeeLevel and Mopeka sell $70-110-per-tank sensor hardware that measures a level but never forecasts days remaining or learns your consumption; one-shot web calculators (Changing Ears, boondocking.ai, solar sizers) have no persistence, use generic assumptions, and need internet — the one thing boondockers lack. RigSens…

Who it's for

Built for anyone who values fast, private, on-device software with a calm, focused UX.

In one line: Off-grid days left, per tank

Try it

See the Off-grid days left, per tank for the full feature list, the info table, and support links.

Use DryDays, found a bug, or have a feature request? Comments are open below — anonymous is fine.