If electric is 8.4 cents per KW where is the break even point for propane with a high efficiency furnace.
It's been cold up here, the electric Co. cut off the off peak rate from May 20 to Aug 20.
I'm wondering if I'm better to use some $1.90 per gal. propane.

Wow...worrying about heating bill in July!!!!!!
I finally broke down and turned on the central air about 3 weeks ago. Just getting too humid and hot here.
My circumstances are much different here. Don't know how to answer you. Gas heat used to be cheaper than electric but not now. Electric bill goes up about 200 per month for two coldest months of winter and about 100 for the other couple of months.
Few years back, I went with my Uncle to Bayfield Co. Wisconsin to deer hunt with friends of his at a cabin they owned.
Heavy respect for Packers and Vikings after that for playing in such cold weather.

I installed water heat tubes under the floor in my house. Had it hooked to a 40 gallon propane water heater. The 1st winter my propane bill was $2800.00 so last year i switched to 30 gallon electric. Total eletric for heat i figured about $800.00 an i used 40% propane on 500 gallon tank. I figured i cut my heat bill in half be switching to electric.

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Heavy respect for Packers and Vikings after that for playing in such cold weather.

Actually, the Vikings play in a dome. But you're right it is ridiculously cold up there!!

Somebody knows 8.4 cents per KW elec. = how much per gallon?

Keep in mind that electric heat is not near as "hot" as propane or natural gas. It has to be judged by the actual usage to attain the same amount of comfort. My last two homes have electric heat and you tend to stay not warm enough. Even in Texas. With AEP/Swepco we have the cheapest electricity in the country but if I would have had access to natural gas I would have chosen it for my heat.