Yes, theoretically, your calculation is correct, and it would likely pass code based on conduit fill alone. However, there are critical caveats and considerations

You are correct in the following:
40% Fill for >2 Conductors

For more than two conductors, the maximum allowable conduit fill is indeed 40%.

Conductor Areas (Approximate)

Your stated conductor areas are close to typical values found in NEC Chapter 9 Table 5. You can confirm these numbers below.

Calculation

Your calculation accurately sums the conductor areas and compares it to the allowable fill.

However, you MUST verify the following before proceeding



Exact Conductor Dimensions

The actual dimensions of the conductors being used are crucial. Manufacturer specifications can vary slightly.

Do NOT use the approximate values from the NEC unless you can't get the actual dimensions. Find the specific data sheet for the conductors you are using. This is the most common error when calculating conduit fill. Conduit Type and Size

You haven't specified the conduit type or size. The conduit needs to be large enough to accommodate the conductors within the 40% fill limit and be appropriate for the application. Remember that a standard size EMT or Rigid conduit might not exist to meet a minimum ID requirement.

Derating for Number of Conductors

More than three current-carrying conductors in a conduit requires ampacity derating. This is a separate calculation independent of the conduit fill calculation. This is likely if you are running two hots and a neutral. The derating can necessitate using larger conductors than originally planned.

Conductor sizes

The values listed are approximate and derived from NEC chapter 9 table 5. 6 AWG THWN: 0.0819 in² 10 AWG THWN: 0.0340 in²2 .0819 + .0340 = 0.1978 in²You will need at least a 1" conduit.

Other Important Considerations



Practicality

While it might theoretically fit, pulling the conductors through the conduit could be very difficult, especially with bends. It's generally good practice to leave some extra space for easier pulling and future modifications.

Box Fill

Don't forget to check the fill capacity of any junction boxes or enclosures where these conductors terminate. Box fill calculations are separate from conduit fill and are often overlooked.

Local Amendments

Always check for any local amendments to the NEC that might be in effect in your jurisdiction.

Professional Judgement

Even if everything checks out on paper, a qualified electrician might advise against a tight fill for practical reasons or long-term reliability.

Type of Load

If the load on the 6 AWG conductors is continuous (3 hours or more), it's more than likely that you will need to use larger conductors to compensate for voltage drop and other considerations.

In summary

Yes, based only on the numbers you provided and the 40% fill rule, it appears to meet the minimum requirement.

However, you MUST verify all the caveats listed above, especially conductor dimensions, conduit type/size, and ampacity derating. Consulting with a licensed electrician is highly recommended. Don't rely solely on these calculations without a thorough assessment of the entire installation. Flag for review