Question 1

What does this TDI calculator calculate?

Accepted Answer

This TDI calculator estimates the required TDI parts by weight for a polyurethane foam formulation based on polyol OH value, water level, reactive equivalents, TDI %NCO and target isocyanate index.

Question 2

Can this TDI calculator be used for flexible PU foam?

Accepted Answer

Yes. This TDI calculator is designed mainly for flexible polyurethane foam formulation checks, including slabstock foam, molded foam trials, water-blown systems and production-side TDI demand review.

Question 3

What %NCO should I use for TDI?

Accepted Answer

A common TDI %NCO value is around 48.3%, but production calculations should use the actual value from the supplier certificate of analysis whenever available.

Question 4

Why is water included in the TDI calculation?

Accepted Answer

Water reacts with isocyanate and consumes NCO groups while generating carbon dioxide for chemical blowing, so water must be included in the reactive hydrogen calculation.

Question 5

Is this TDI calculator the same as an isocyanate index calculator?

Accepted Answer

This page is TDI-specific. For MDI, p-MDI or general NCO index calculations, use the PolymersIQ Isocyanate Index Calculator.

Question 6

Should I use supplier COA values in the TDI calculator?

Accepted Answer

Yes. For production formulation work, use the actual TDI %NCO, polyol OH value and moisture values from supplier COA data whenever available because small raw material variation can change the calculated TDI demand.

TDI Calculator for Polyurethane Foam

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