Crate Engines
Engine Components
Oiling System
Cooling System
Chassis & Suspension
General information
Performance Services
Exclusive Products
Dyno Results
Blueprinted Engines
Cylinder Heads
Springs & Perches
1/4 Mile Performance
Horse Power
Gear Ratio
Rearend Ratio
Compression Ratio
Reaction Time
Free & Fun Stuff
11 's on a budget
Printable Calendars
Photo Galleries
Our Pbase Galleries
Our Swap Meet
Our Favorite Links
Return to home page
The Nitemare Performance Gear RPM Calculator

Input - Enter/select your values then click the calculate button below.
The default values shown are for a TH400 equipped muscle car with a typical street rim tire combination.

1st gear ratio: 2nd gear ratio: 3rd gear ratio:
4th gear ratio: 5th gear ratio: 6th gear ratio:
Rear axle ratio: Speed (mph):

The RPMs* required for your selected combination and speed in each gear are:-
1st gear RPM is: 2nd gear RPM is: 3rd gear RPM is:
4th gear RPM is: 5th gear RPM is: 6th gear RPM is:

* Note:- We are not responsible for any potential errors. Always verify all calculations before making changes and driving your vehicle!
These calculations will be most accurate when performed for manual transmission equipped vehicles or automatic transmission vehicles with lock-up torque convertors (with the convertor in the locked state). The values for automatic transmission vehicles with "open" convertors can be corrected for slippage by the addition of 200-500 rpm which is typical for quite a wide range of convertors during light cruise to near coast conditions. During hard acceleration the values for unlocked convertor will vary by a wide margin with the locked state only being approximated at maximum RPMs. These calculations also assume a constant wheel radius, which in reality does not occur due to two major factors tire wall sag due to vehicle weight decreasing the effective radius (most apparent in high profile radial tires) which could result in up to a 4% under estimate of RPMs, and centrifugal tire growth (most apparent in drag racing tires) which will increase the effective wheel radius, and hence decrease the RPM values required to maintain the vehicle at a set speed by 1-5%.