I am self employed with 60 K net income. Turbo tax calculates my self employed 401K at 14 K which is very low. What is correct method to get appropriate calculation?

Here is a calculator   https://scs.fidelity.com/products/mobile/sepMobile.shtml

Do you have a job with a 401K contribution already?

I used the Fidelity numbers but TT said I was over contributed and did not give tax benefit

Do you have other income from a job and have a retirement plan?

no

It overrides me and enters a number as a Keogh contribution

Is this a 401K or SEP IRA?