Hydrology Formulator vs Distant
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Hydrology Formulator
This app provides a comprehensive collection of over 1,000 formulas, calculators, and conversions for hydrology and civil engineering. It covers a wide range of topics including groundwater, stormwater, pipe flow, and water pollution.
- 1,000+ formulas and calculators
- Groundwater analysis tools
- Stormwater design calculations
- Open channel and pipe flow equations
- Water pollution modeling
- Conversions and reference data
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HYDROLOGY FORMULATOR is the ultimate pocket reference for hydrologists, civil engineers, environmental scientists, and students. Packed with 1,000+ formulas, calculators, and conversions, it covers everything from groundwater analysis to stormwater design — all in one powerful app. HYDROLOGY CALCULATORS Infiltration & Recharge — 17 Calculators - Porosity, Green-Ampt Infiltration, Horton Infiltration, Philip Infiltration, Holtan's Model, Hydraulic Conductivity, Groundwater Recharge, Mean Pore Velocity, Specific Discharge, Volumetric Water Content, and more Evaporation & Transpiration — 8 Calculators - Penman-Monteith ET0, Blaney-Criddle ET, Thornthwaite PET, Crop Evapotranspiration, Saturation Vapor Pressure, Evaporation Rate of Lake, Relative Humidity, Potential Evapotranspiration Open Channel Flow — 12 Calculators - Manning's Equation (SI & US), Chezy Equation, Froude Number, Hydraulic Radius, Hydraulic Jump, Critical Depth, Specific Energy, Reynolds Number, and more Pipe Flow — 7 Calculators - Darcy-Weisbach Equation, Hazen-Williams Velocity (SI & US), Reynolds Number, Water Hammer Pressure, Continuity Equation, Minor Head Loss Stormwater & Watershed — 9 Calculators - SCS Curve Number Runoff, SCS Peak Discharge, IDF Rainfall Intensity, Kirpich Time of Concentration, Gumbel Extreme Value, Detention Storage Volume, Composite Curve Number, and more Pumps & Water Supply — 7 Calculators - Total Dynamic Head, Water Horsepower, Brake Horsepower, NPSHa, Affinity Laws for Flow, Head, and Power Weirs & Orifices — 6 Calculators - Rectangular Weir (SI & US), V-Notch Weir, Broad-Crested Weir, Orifice Flow, Spillway Discharge Water Flow — 10 Calculators - Water Flow Rate, Velocity of Water, Volume of Water Flow, 90° V-Notch calculations, Pipe Total Diameter, and more Surface Runoff — 6 Calculators - Average Velocity, Runoff, Travel Time, Hourly Rate of Rainfall Groundwater — 7 Calculators - Darcy's Law, Thiem Equation, Cooper-Jacob Drawdown, Dupuit Well Flow, Radius of Influence, Storage Properties Soil Pollution — 5 Calculators - Groundwater Pore Velocity, Effective Diffusion, Hydrodynamic Dispersion, Aquifer Parameter, Variance of Pore Velocity River Pollution — 7 Calculators - River Oxygen Deficit, Critical Time & Distance for Oxygen Deficit, Re-Aeration Constants, Dissolved Oxygen, River Flow, Water Temperature Lake Pollution — 4 Calculators - Waste Entering, Equilibrium Concentration, Settling Loss Rate, Particle Deposition Rate Sediment Transport — 4 Calculators - Shields Parameter, Bed Shear Stress, Stokes' Law Settling Velocity, Meyer-Peter Müller Bedload Snow Hydrology — 2 Calculators - Snow Water Equivalent, Degree-Day Snowmelt Culvert Hydraulics — 2 Calculators - Culvert Headwater (Outlet Control), Culvert Outlet Control Head Loss Flood Routing - Muskingum Routing Water Balance - Water Balance Equation, Storage Continuity Plus: Area Formulas, Pollution Cleanup, and more CONVERSIONS & REFERENCE Hundreds of built-in conversions across 16 categories including: - Liquid Measures, Cubic Measures, Linear Measures, Square Measures - Flow Rates, Pressures, Horsepower, BTU, Watts, Power - Hydraulic Conversions, Sand-to-Volume, Ft-Lbs - 8 Temperature Scales (Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Newton, Delisle, Rømer) - Metric Conversions and Fraction Conversions KEY FEATURES - Save and review past calculations - Switch between US (Imperial) and Metric units - Clean, intuitive interface designed for field and office use - Premium upgrade unlocks Groundwater, Pollution, Sediment Transport, Snow Hydrology, Culvert Hydraulics, and Flood Routing calculators
Distant
Enhance concentration with a premium focus timer that blocks distracting applications. Track your progress with detailed analytics and celebrate achievements. Customize your sessions and themes for a personalized productivity experience.
- App blocking for distractions
- Customizable focus sessions
- Detailed progress analytics
- Achievement system
- Intuitive dark interface
- Multiple timer modes
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Distant is a premium focus timer designed to help you disconnect from digital distractions and reclaim your time. Set a focus session, block distracting apps, and stay present in what matters most. Beautiful, Intuitive Design Dark, premium interface with tactile dial controls Smooth animations and haptic feedback Customizable themes and gradients Multiple timer appearance modes (Standard, Minimal, Detailed) Powerful Focus Features Focus sessions from 1 to 240 minutes Deep Focus mode for extended concentration Quick presets for instant session starts Custom focus types (Work, Study, Reading, Meditation, etc.) Pause and resume sessions as needed Emergency override with a 5-minute break Track Your Progress Detailed analytics and insights Session history with completion tracking Achievement system to celebrate milestones Experience points and level progression Focus streaks and statistics Smart Notifications Progress updates during sessions Session completion alerts Motivational reminders In-app notification center Customization Personalize colors and gradients Configure quick preset durations Toggle features to match your workflow Available in 10 languages
Screenshots
Verdict
The clearest difference is update cadence: Distant at fortnightly against Hydrology Formulator's every 6 months. Hydrology Formulator's advantage is iOS requirement (18.6 vs 26.0). On price, rating, ratings volume and ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Hydrology Formulator sells 1 one-off in-app purchase and Distant sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
On the App Store both sit at effectively the same score — 5.0 for Hydrology Formulator against 5.0 for Distant. Both are backed by a comparable volume of ratings — 1 and 1 respectively.
Hydrology Formulator ships an update every 6 months, Distant fortnightly. The most recent releases landed on October 8, 2026 and October 23, 2026 respectively.
| Parameter | Hydrology Formulator | Distant |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) | 5.0 (1 ratings) |
| Positive reviews | 0.0% of reviews | — |
| Number of ratings | 1 | 1 |
| Update frequency | Every 6 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free | Free |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 18.6 — better | 26.0 |
| Further details — not scored | ||
| Size | 18 MB | 6 MB |
| Age rating | 4+ | 4+ |
| Developer | Historycentral.com | Odd Omens |
Customer experience
Hydrology Formulator
Distant
In-app purchases
Hydrology Formulator
- Pro Version$3.99
Distant
- Distant Full Access$3.99









