Each new mobile account receives four days of full access to every calculator and tab without starting a subscription or entering payment information. After the trial ends, the current product catalog uses auto-renewing six-month subscriptions. Apple App Store or Google Play displays the authoritative localized price, billing period, taxes, and any introductory offer before confirmation. The tier controls which tools you can use after the trial.
| Subscription | How it works | Best for |
|---|---|---|
| Six-month auto-renewing | Pay the localized amount shown by Apple or Google at purchase. The current catalog term renews every 6 months from the purchase date. | Customers who want uninterrupted access. |
| Cancel anytime | Cancel renewal in the Apple App Store or Google Play settings. Access remains available through the current paid 6-month period; a new purchase is required after expiration. | Customers who only need one term. |
Mobile installs receive a secure passwordless app session automatically. The server starts the four-day trial on that permanent account so closing and reopening the app does not reset the trial clock. No separate customer username, name, email address, or password is required for trial access, an Apple App Store or Google Play purchase, restoration, or subscription management. If subscription controls are still loading, wait for the app session to finish and try again.
Tap the bottom tabs to move between PDP, Multi-Leg, Heli / WT, Thermo, Tools, Map, and Contact. Newer iPhones may show Apple's native translucent tab style; older iOS versions and Android use the classic tab bar. The tools and calculations are the same.
Calculators support relevant Imperial and Metric units. Unit selectors convert the associated displayed values where supported; small differences may appear from rounding. Review every value after changing units, especially before field use.
The app follows your device's system appearance (Light / Dark) by default. To override, go to the Tools tab → scroll to Appearance and select Light, Dark, or System.
Calculates the required pump discharge pressure (PDP) for a single hose lay, accounting for friction loss, elevation change, and nozzle pressure. Also recommends the number of relay engines needed and their spacing.
Direct Flow: Enter a known flow rate directly. Use when you know your GPM/LPM from a flow meter or plan.
Nozzle Calc: Enter nozzle tip diameter and nozzle pressure — the app derives flow using the nozzle formula Q = 30 × d² × √NP. The calculated flow is then used for all PDP calculations.
| Output | Description |
|---|---|
| Elevation Difference | Net vertical rise between pump and target (ft or m) |
| Elevation Pressure | Back-pressure or pressure gain from elevation (PSI or kPa) |
| FL per 100 ft / Effective FL/100 ft | Friction loss per 100 ft for the selected hose and flow. With 2+ parallel lines the label changes to Effective FL/100 ft (N lines) — this is the system friction rate after splitting flow across all lines (FL reduced by N²) |
| Total Friction Loss | Total friction loss across the full hose length, accounting for parallel lines if selected |
| Engine PDP | Required pump discharge pressure — the primary result |
| Engines Required | Number of relay engines needed (Engine PDP ÷ Max Engine PDP), calculated using the effective (parallel-adjusted) friction loss |
| Engine Spacing | Recommended spacing between relay engines, rounded to the nearest 100 ft to align with real hose section lengths |
| Per-Engine Segment Breakdown | When 2+ engines are required: segment length (rounded), parallel lines count and flow per line (when >1 line selected), friction loss for the segment, elevation head, nozzle pressure (÷ engines), and individual engine PDP |
A quick-reference table always shown at the bottom. Given your flow, hose, NP, and max PDP settings, it shows the maximum recommended relay spacing for 1, 2, 3, and 4 parallel lines on flat terrain — useful for pre-plan spacing without elevation.
Plans complex hose lays with multiple legs of different hose diameters, lengths, and elevation changes. Calculates cumulative PDP, identifies critical high points, and plans relay pump placement. Supports data import directly from the Map Planner.
The app starts with two legs. Tap Add Leg to append a new leg (copies the preceding leg's diameter). Tap the trash icon to remove a leg. Up to 30 legs are supported.
| Output | Description |
|---|---|
| FL / 100 ft | Friction loss rate for this leg's diameter and flow |
| Total Friction Loss | Total friction loss for this leg's length |
| Elevation Head | Back-pressure contribution from this leg's elevation change |
| Leg PDP | Pump pressure required to push through this leg |
| Hose Velocity | Water velocity in ft/s — flag for high-velocity conditions |
| Travel Time | Time for water to traverse this leg (minutes) |
| Cumulative PDP | Total pump pressure required from the source to end of this leg |
Shown when two or more legs are configured: total distance, net elevation change, total friction loss, total system PDP, and total water travel time.
Enter the Max Safe Pump Pressure in the Relay Planner card. The app greedily groups consecutive legs, checking whether a single pump can handle the combined friction loss + elevation head + nozzle pressure within your rated maximum. It then reports:
When enabled, the nozzle pressure is divided equally across all calculated relay pumps rather than being applied only at the final pump. Useful for planning where no single pump bears the full NP burden.
A global Add Parallel Line comparison card shows the system-wide friction loss reduction from doubling the lay — single-line total FL vs. parallel FL (÷4, 75% reduction). This is display-only and does not affect the relay planner; use the per-leg Parallel Line checkbox to include it in calculations.
After plotting a route in the Map Planner and tapping Send to Multi-Leg, switch to the Multi-Leg tab. The app asks whether to replace the current legs with the map data. On import:
The Tools tab contains two utility calculators selected with the FL and Nozzle sub-tabs at the top of the screen.
Quickly compares pump discharge pressure across 1 to 4 parallel hose lines for a given flow, hose diameter, length, and elevation. Useful for rapid pre-plan comparisons without setting up a full Multi-Leg layout.
Solves for any one of the three variables in the nozzle flow formula: Q = 30 × d² × √NP. Select what you want to calculate, enter the other two values, and the result appears instantly.
| Mode | You Enter | You Get |
|---|---|---|
| GPM | Nozzle tip diameter + nozzle pressure | Flow rate (GPM or LPM) |
| Diameter | Desired flow rate + nozzle pressure | Required tip diameter (in or mm) |
| Pressure | Desired flow rate + tip diameter | Required nozzle pressure (PSI or kPa) |
A Common Nozzle Flows quick-reference table is shown below the calculator, displaying typical GPM outputs at standard pressures for common nozzle tip sizes.
Scroll to the bottom of the Tools tab to find the Appearance setting. Toggle between Light, Dark, and System (follows device setting).
Calculates helicopter water delivery rates and water tender resupply capacity. Compares helicopter output against tender supply to determine whether aerial operations are water-limited.
When both sections have valid inputs, the app computes the supply match percentage — the ratio of tender supply GPM to helicopter demand GPM. Below 100% means the tenders cannot keep up with helicopter demand; above 100% means tenders have excess capacity.
Calculates the heat absorption capacity of a water delivery system — the thermal energy the water can absorb before it boils away — accounting for altitude-corrected boiling points and initial water temperature. Includes BlazeTamer foam enhancement.
Three large numbers across the top of the screen show your system's heat absorption capacity in your chosen unit set:
| Display | What it means |
|---|---|
| kW | Thermal power absorbed (kilowatts) — standard international fire behavior metric |
| MJ/hr | Energy per hour (megajoules) — useful for comparing against fire behavior models |
| BTU/min | Imperial thermal power rate — common in US wildland fire operations |
| BTU/hr | Imperial hourly total — useful for extended operations planning |
Detailed table showing the thermal contribution of each heat-transfer phase:
| Row | Description |
|---|---|
| Boiling kW / BTU/min | Energy absorbed heating water from inlet temp to boiling point (sensible heat) |
| Steaming kW / BTU/min | Energy absorbed converting liquid water to steam at the boiling point (latent heat — the dominant component) |
| Total Absorbed | Combined thermal absorption capacity of your water delivery system |
| Enhanced (BlazeTamer) | Shown when BlazeTamer is enabled — total × 1.43 multiplier |
An interactive map for plotting hose routes, dip sites, and reference points. Automatically fetches terrain elevation for each pin. Routes can be exported directly to the Multi-Leg calculator.
| Mode | Icon | Best For |
|---|---|---|
| Satellite | SAT | Default view — high-resolution aerial imagery for terrain recognition |
| Topo | TOPO | USGS National Map with contour lines — best for elevation planning |
| Terrain | TER | Topographic basemap with contours, hillshading, and labels (Google Terrain on Android; ESRI on iOS) |
| Relief | REL | Grayscale hillshade overlay on satellite — emphasizes landform shape |
| Road | ROAD | Standard road map — useful for locating access roads and infrastructure |
Make sure the toolbar is in Pin mode (pin icon active). Tap anywhere on the map to place a pin. The app immediately fetches the terrain elevation for that location from the USGS Elevation API. Each pin is numbered sequentially.
Location permission is optional for manual planning. Grant it if you want to use the lower-left center-on-location control or live compass. Map tiles and elevation lookup require a network connection.
Tap a pin to open its callout. From the callout you can:
Long-press and drag any pin to reposition it. Elevation is re-fetched automatically after a drag.
Tap the ft / m toggle to switch displayed elevations. All pin elevations and the route summary update simultaneously.
Switch the toolbar to Measure mode (ruler icon). Position the map crosshair over the first location and set point A, then move the map and add point B and any additional points. The route panel shows segment and cumulative distance. Toggle between km, NM, and mi using the unit selector.
Measure points include editable coordinates and online elevation lookup. Once elevations load, the summary reports total gain, total loss, and net elevation change. A loading or unavailable elevation must be resolved before relying on those totals.
Use Save Route to retain a measured route and Saved Routes to load it later. Up to 20 routes are stored locally on that device; they are not synced to an account or another phone.
The upper-left compass uses the phone's live physical heading while the Map tab is active. T is the true-north heading after local magnetic-declination correction. M is the raw magnetic heading. DEC shows the correction in degrees east or west; for example, DEC 12°E.
The wider primary needle indicates declination-corrected true north, while the thinner secondary needle indicates magnetic north. A dash means the corresponding sensor value is not yet available. Move away from metal, vehicles, magnets, and electrical equipment if the magnetic reading appears unstable.
Once pins are placed and elevations loaded, tap Send to Multi-Leg. This packages the route — leg lengths, elevation changes, pin labels, and absolute elevations — into a format the Multi-Leg calculator can import. Switch to the Multi-Leg tab and confirm the import when prompted.
Tap Clear to remove all route pins. This also clears data previously imported into Multi-Leg, resetting it to two blank legs. An active measurement route may require its own measurement-mode control.
Use the feedback form to report bugs, request features, or ask questions. Wait for the secure app session to finish loading, tap Send Feedback, enter your message, and submit. An optional screenshot may request photo-library permission. Do not include passwords, payment details, patient information, or other sensitive data.
The Contact tab shows the current access state and store subscription controls:
Apple App Store and Google Play handle purchase, confirmation, renewal, cancellation, and restoration through the store account. Use Manage Subscription to open the applicable store settings, or Restore Purchases to recover access on another device with the same store account. The app never asks for your Apple/Google password or payment-card details and does not use Stripe checkout or a web billing portal.
The Contact tab includes the WildCalc website, newsletter, developer contact methods, disclaimer, Privacy Policy, and Apple Standard EULA. The same legal links are available from the Pricing screen.
| Hose Diameter | Typical Coefficient | Notes |
|---|---|---|
| 1" | C = 150 or 250 | 250 for modern forestry hose; 150 for older hose |
| 1½" | C = 24 or 35 | 35 for cotton-jacketed; 24 for modern synthetic |
| 1¾" | Built-in | Standard attack hose |
| 2", 2½", 3" | Built-in | Supply and relay hose |
| 3½", 4", 5" | Built-in | Large-diameter supply hose |
Q = 30 × d² × √NP
Q = flow (GPM) · d = nozzle tip diameter (inches) · NP = nozzle pressure (PSI)
| Parallel Lines | Effective FL Rate | Reduction |
|---|---|---|
| 1 line | Full FL/100ft | — |
| 2 lines | FL ÷ 4 | 75% |
| 3 lines | FL ÷ 9 | 89% |
| 4 lines | FL ÷ 16 | 94% |
| Imperial | Metric |
|---|---|
| 1 GPM | 3.785 LPM |
| 1 PSI | 6.895 kPa |
| 1 ft | 0.305 m |
| 1 mile | 1.609 km / 0.869 NM |
| 1 gallon | 3.785 L |
| 1 BTU/min | 0.01758 kW |
Use this space for verified assumptions, agency standards, hose inventory, weather observations, and other planning notes.