Energy and household resources

Hot-water mixing calculator

Ideal energy balance for water, neglecting heat loss and density change.

Your numbers

Use the units shown. Results update as you change valid inputs.

YOUR RESULT

Ideal energy balance for water, neglecting heat loss and density change.

THE NUMBERS, EXPLAINED

How to use this calculator.

Ideal energy balance for water, neglecting heat loss and density change.

Start with your inputs

Enter hot temperature (°c), cold temperature (°c), target temperature (°c), final volume (l). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.

InputExample value
Hot temperature (°C)60
Cold temperature (°C)10
Target temperature (°C)40
Final volume (L)100

A worked example

With the example inputs above, hot water (l) is 60. Change the inputs to explore your own scenario.

Putting the example numbers into the formula

Hot water (L)
(100) × ((40)-(10)) ÷ ((60)-(10)) = 60

Cold water (L)
(100) × ((60)-(40)) ÷ ((60)-(10)) = 40

All results for the example inputs above
ResultExample answer
Hot water (L)60
Cold water (L)40

How this is calculated

Hot water (L)

d × (c-b) ÷ (a-b)

Cold water (L)

d × (a-c) ÷ (a-b)

Symbols and units
a
Hot temperature (°C)
b
Cold temperature (°C)
c
Target temperature (°C)
d
Final volume (L)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions and limits

Ideal energy balance for water, neglecting heat loss and density change.

Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.

Questions about this tool

What does the result tell me?

Hot water (L); Cold water (L). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.

Why might another calculator differ?

Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Ideal energy balance for water, neglecting heat loss and density change.

Are my inputs stored or sent to AI?

Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.

Review status

Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.

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