Add a free aquarium calculator to your website

Fish stores, aquarium clubs and hobby blogs can put any ScapeMath calculator on their own pages. It's free with no sign-up, the embedded version has no ads, and your visitors can switch between litres and US gallons (metric or US units).

Pick a calculator below, press Copy code, and paste it into your site with the steps for your website builder. Please keep the small "Calculator by ScapeMath" credit line under it.

How to add it to your site

Every calculator uses the same two lines of HTML: the calculator itself (an iframe) and a credit link. Paste both.

Squarespace (Code block)

1. Open the page and click Edit, then click an insert point (+) where you want the calculator.
2. Choose Code from the block menu.
3. Delete the sample text, paste the embed code, and make sure the mode is HTML and Display source is off.
4. Click outside the block, then Save. The calculator shows on the live page (the editor may show a placeholder).

Squarespace only runs iframes in Code blocks on some plans. If you see the code as text or nothing at all, email us and we'll find another way.

WordPress (Custom HTML block)

1. Edit the page or post, click + (Add block) and search for Custom HTML.
2. Paste the embed code into the block.
3. Click Preview in the block toolbar to check it, then Update or Publish.

Using the Classic editor? Switch to the Text tab before pasting. Some WordPress.com plans remove iframes; self-hosted WordPress keeps them.

Wix (Embed HTML or Embed a Site)

1. In the Wix Editor, click Add Elements (+), then Embed Code, then Embed HTML.
2. Click Enter Code, choose Code, paste the embed code and click Update.
3. Drag the element's handles so it's as tall as the height in the code (for example 720 px), then Publish.

Or choose Website address (Embed a Site) and paste just the calculator's address, for example https://scapemath.com/embed/heater-size/. Then add a text link to the full calculator under it as the credit.

Shopify (pages: show HTML)

1. In Shopify admin go to Online Store → Pages and open the page (or add a new one).
2. In the content editor click Show HTML (the <> button) to switch to code view.
3. Paste the embed code where you want the calculator and click Save.

In the theme editor you can also add a Custom Liquid section and paste the same code.

Plain HTML

Paste the embed code into your page's HTML where the calculator should appear, inside <body>. Nothing else is needed: no scripts, no API key.

Adjusting the height

Each code already has a height that shows the whole calculator on phones and desktops. If yours looks cut off or leaves a gap, change the number in height="720" (in pixels). The width fills your column up to 680 px. For help, another size or a calculator we don't have yet, email [email protected].

Calculators you can embed

Tank volume & water weight

How many gallons or litres your tank holds: rectangular, cylinder, bow-front, corner and hexagon, plus water weight. Open the full aquarium volume calculator.

Embed code (height 900 px) <iframe src="https://scapemath.com/embed/tank-volume/" title="Aquarium volume calculator in gallons &amp; litres by ScapeMath" width="100%" height="900" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/tank-volume/">ScapeMath: aquarium volume calculator in gallons &amp; litres</a></p>

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Substrate: sand, gravel & aquasoil

How many pounds or kilograms of sand or gravel, or litres of aquasoil, for a flat or sloped bed, and how many bags to buy. Open the full substrate calculator.

Embed code (height 900 px) <iframe src="https://scapemath.com/embed/substrate/" title="Aquarium substrate calculator by ScapeMath" width="100%" height="900" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/substrate/">ScapeMath: aquarium substrate calculator</a></p>

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Water change & dilution

What a water change does to nitrate, salinity or hardness, how much to change to hit a target, and RO/tap blends. Open the full water change calculator.

Embed code (height 700 px) <iframe src="https://scapemath.com/embed/water-change/" title="Water change &amp; dilution calculator by ScapeMath" width="100%" height="700" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/water-change/">ScapeMath: water change &amp; dilution calculator</a></p>

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Fertilizer dosing (dry salts)

Grams to ppm and back for KNO₃, KH₂PO₄, K₂SO₄ and Epsom salt, plus stock solutions and an EI-style planner. Open the full fertilizer dosing calculator.

Embed code (height 1350 px) <iframe src="https://scapemath.com/embed/fertilizer-dosing/" title="Fertilizer dosing calculator (dry salts) by ScapeMath" width="100%" height="1350" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/fertilizer-dosing/">ScapeMath: fertilizer dosing calculator (dry salts)</a></p>

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CO₂ from pH & KH

Dissolved CO₂ from your pH and KH readings, with temperature correction, and the pH that matches your target. Open the full CO₂ calculator.

Embed code (height 820 px) <iframe src="https://scapemath.com/embed/co2-ph-kh/" title="CO₂ from pH &amp; KH calculator by ScapeMath" width="100%" height="820" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/co2-ph-kh/">ScapeMath: co₂ from ph &amp; kh calculator</a></p>

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Salinity & specific gravity

Convert hydrometer SG to ppt with temperature correction (EOS-80), and see what your instrument should read. Open the full salinity converter.

Embed code (height 760 px) <iframe src="https://scapemath.com/embed/salinity/" title="Salinity &amp; specific gravity converter by ScapeMath" width="100%" height="760" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/salinity/">ScapeMath: salinity &amp; specific gravity converter</a></p>

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Hardness & alkalinity units

Convert KH between dKH, ppm and meq/L, and GH between dGH, ppm, mmol/L and grains per gallon, or work out GH from Ca and Mg. Open the full KH & GH converter.

Embed code (height 760 px) <iframe src="https://scapemath.com/embed/hardness-alkalinity/" title="Water hardness &amp; alkalinity converter by ScapeMath" width="100%" height="760" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/hardness-alkalinity/">ScapeMath: water hardness &amp; alkalinity converter</a></p>

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Heater wattage

How many watts your tank needs, from volume, room and target temperature, and optional evaporation. Open the full heater size calculator.

Embed code (height 720 px) <iframe src="https://scapemath.com/embed/heater-size/" title="Aquarium heater size calculator by ScapeMath" width="100%" height="720" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/heater-size/">ScapeMath: aquarium heater size calculator</a></p>

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Filter size & flow rate

What GPH or L/h filter your tank needs, how much flow is lost to media and plumbing, and reef return pump and powerhead flow. Open the full filter size calculator.

Embed code (height 760 px) <iframe src="https://scapemath.com/embed/filter-flow/" title="Aquarium filter size &amp; flow rate calculator by ScapeMath" width="100%" height="760" style="border:0;max-width:680px" loading="lazy"></iframe> <p style="font-size:13px">Calculator by <a href="https://scapemath.com/tools/filter-flow/">ScapeMath: aquarium filter size &amp; flow rate calculator</a></p>

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The embedded calculators run in your visitors' browsers and don't set cookies or collect what they type. See our privacy policy.