CNC Coolant Top-Up calculator: simplify your coolant management

Note: This calculator is designed for CNC machining coolants used in metalworking, not automotive antifreeze.

Accurately calculate top up volumes and new fill ratios for your CNC machine coolant. The calculator accounts for evaporation, coolant loss and refractometer correction, helping you maintain stable concentration, extend coolant life and protect your tooling.

For detailed explanations and formulas, see the full article.

For New Fill

Desired concentration, %

Refractometer factor

Tank volume, Gal

Results:

Gal, of concentrate required

Gal, of water required

Readings on refractometer

For Top Up

Desired concentration (real), %

Concentration in tank (readings), %

Refractometer factor

Tank volume, L

Remaining volume in tank, L

Results:

Concentration in tank (real)

Desired concentration (readings)

Required concentrate, L

Top-up volume, L

Concentration in top-up (real)

Concentration in top-up (readings)

For a full explanation of concentration formulas, refractometer correction and top up ratios, see the complete coolant top up article.

Recommended CNC Coolants

Tip: Working with coolant daily? Reduce foaming, stabilize pH and extend sump life with CNC grade coolants designed for industrial machining:

UNI301 - Universal semi synthetic coolant for milling and turning.
PRO302 - High performance coolant amd aluminum champion.
BASE201 - Our top seller for non demanding cutting operations

CNC Coolant vs Automotive Coolant

CNC coolant, also called metalworking fluid, is designed for chip evacuation, lubrication and heat removal during machining. Automotive coolant is designed for engine thermal management. They are not interchangeable.

This calculator applies only to metalworking fluids.