Aquascape planning
Live rock calculator
Estimate live rock, dry rock, mixed rock, box count and displacement from display volume, aquascape style and rock density.
- Live or dry rock
- Box count
- Displacement
Free reef tools - 12 calculators
Reef tank calculators and coral care tools.
12 practical coral tools for checking reef tank lighting and choosing a safer starting placement.
Which reef calculator is right for you?
Reef tank coral decisions often start with one question: are you checking light intensity, or are you choosing a physical spot in the aquascape? Use the calculators below before changing lighting, flow, spacing, or coral position.
For reef rock and aquascape planning
Use the Live Rock Calculator when you are deciding how much live rock or dry rock to buy, whether an open aquascape needs biomedia support, and how much water volume the rock may displace.
Available tool: Live Rock Calculator.
For actual water volume
Use the Reef Tank Water Volume Calculator when you need a better estimate than nominal tank size. It supports multiple tank shapes, waterline height, sand and rock displacement, sump operating volume, and water change percentages.
Available tool: Reef Tank Water Volume Calculator.
For water changes and nutrient dilution
Use the Reef Water Change Calculator when you need gallons or liters for a planned change, bucket count, nitrate or phosphate dilution, repeated-change projections, salinity correction estimates, or automatic daily water change equivalents.
Available tool: Reef Water Change Calculator.
For reef sand and substrate planning
Use the Reef Sand Bed Calculator when you are choosing shallow, standard, sloped, partial or deeper sand coverage. It estimates sand pounds, kilograms, bag count and water displacement notes from the tank footprint.
Available tool: Reef Sand Bed Calculator.
For mixing saltwater
Use the Reef Salinity Converter when you need to compare SG and ppt or check a current reading against a target. Use the Reef Salt Mix Calculator when you are preparing RO/DI water, making a water change batch, raising salinity in a mixing container, or planning a safer display tank salinity correction.
Available tools: Reef Salinity Converter and Reef Salt Mix Calculator.
For overall coral care requirements
Use the Coral Care Requirements Lookup when you want the broad care profile for a coral: difficulty, beginner suitability, tank maturity, light, PAR, flow, placement, spacing, feeding, growth behavior, water parameter sensitivity, and common warning signs.
Available tool: Coral Care Requirements Lookup.
For coral compatibility planning
Use the Coral Compatibility Checker when you want to know whether two corals make sense in the same reef tank or whether one coral fits your current reef style. It weighs light, flow, aggression, spacing, growth control, chemical risk, and tank maturity.
Available tool: Coral Compatibility Checker.
For coral aggression and spacing
Use the Coral Aggression & Spacing Checker when two corals are close together, one coral can touch another when expanded, or you need to decide whether sweepers, overgrowth, chemical irritation, or shading are the bigger concern.
Available tool: Coral Aggression & Spacing Checker.
For reef tank lighting
Use the Coral PAR Calculator when you have a measured PAR number or need a rough educational estimate from light strength, tank depth, coral zone, and shading. It compares the number with typical starting ranges for soft corals, LPS, and SPS.
Available tool: Coral PAR Calculator.
For coral flow
Use the Coral Flow Requirements Finder when you want to check typical flow needs for soft corals, LPS, or SPS, or when you are trying to decide whether a coral is getting too little flow, too much direct flow, or a safer indirect pattern.
Available tool: Coral Flow Requirements Finder.
For coral placement
Use the Coral Placement Calculator when you are choosing a starting spot for a coral and want to consider light, flow, tank zone, aggression, and spacing together before moving the coral.
Available tool: Coral Placement Calculator.
When the coral ID is uncertain
These calculators depend on selecting the right coral or coral group. If you are not sure what coral you have, start conservatively and use Coral Identifier to get likely photo-based matches before making major lighting, compatibility, or placement changes.
Available resources: Coral Identifier app, Coral Guides, and Coral Database.
How accurate are the tools?
Every result should be treated as planning guidance, not a guarantee. Reef tanks vary by rockwork, lighting spectrum, water clarity, coral history, flow patterns, and maintenance habits. Use the calculators to avoid rushed decisions, then verify important changes with trusted reef references and careful coral observation.
Substrate planning
Reef sand bed calculator
Estimate reef sand, live sand and bag count from tank footprint, depth, coverage, sand type and livestock context.
- Pounds & kilograms
- Bag count
- Depth guidance
Water volume
Reef tank water volume calculator
Estimate actual water volume from tank shape, water height, displacement, sump operating volume, and water change percentage.
- Gallons & liters
- Sand & rock
- Sump volume
Water changes
Reef water change calculator
Estimate water change volume, bucket count, nitrate or phosphate dilution, repeated changes, salinity adjustment and automatic daily schedules.
- Gallons & liters
- Nutrient dilution
- Salinity planning
Saltwater salinity
Reef salinity converter
Convert specific gravity to ppt, ppt to specific gravity, and compare current vs target salinity.
- SG to ppt
- ppt to SG
- Range status
Saltwater mixing
Reef salt mix calculator
Estimate dry reef salt mix from water volume, current salinity, target salinity, and salt mix type.
- Gallons or liters
- ppt or SG
- Water changes
Coral care
Coral care requirements lookup
Look up typical care requirements for common soft corals, LPS and SPS.
- Difficulty
- Light & flow
- Warning signs
Coral care
Coral compatibility checker
Check whether coral pairs or a new coral plan are likely compatible in your reef tank.
- Care overlap
- Mixed reef risk
- Tank readiness
Coral care
Coral aggression & spacing checker
Check coral spacing risk from coral type, distance, expansion, flow, growth, stress signs, and shading.
- Sweeper risk
- Overgrowth
- Spacing buffer
Coral care
Coral flow requirements finder
Check coral flow requirements and direct-blast risk from coral type, polyp movement, and detritus signs.
- Flow intensity
- Direct blast
- Turnover hint
Coral care
Coral PAR calculator
Check whether measured or estimated reef tank PAR is likely low, high, or in range.
- Measured PAR
- Estimated PAR
- Light range
Coral care
Coral placement finder
Match a coral's likely light and flow needs to the right zone in your aquascape.
- Light zone
- Flow zone
- Aggression
Why use these reef calculators?
1
Decision-focused
Each calculator starts from a real reef task: checking lighting or choosing a starting placement.
2
Beginner-friendly
The page explains when to use PAR guidance and when placement context matters more.
3
App-ready
Use the result on the web, then continue with photo scans and saved coral history in the app.
Track the result in the app.
Use a calculator on the web, then scan corals, compare likely matches, and keep your reef decisions in Coral Identifier.
Coral Identifier
Identify, compare, and save reef corals.
Calculators help with the setup. The app helps when you are looking at a coral and need a practical photo-based starting point.
