Functions: Net to Gross, Employer NI as well as with the free version:

Salary Payroll Wage Calculator is a simple but powerful take home pay calculator that calculates one's net pay based on the UK tax system. This app can accurately calculate net pay based on any of the following pay frequencies weekly, 2-weekly, 4-weekly, monthly and yearly.

Salary Payroll Wage Calculator can also take Auto Enrolment style pension schemes. Whatever Tax Code be it emergency tax code (1250L, 1250L W1, 1250L M1 or 1250L X), 1250L, D0, NT, BR, K-Codes, T-Codes, M-Codes, N-Codes, this app calculates net pay with ease and perfect accuracy.
Can calculate using all NI categories: employees in a contracted-out workplace pension scheme (D, E, C, L, I, K) employees not in contracted-out pension schemes (A, B, C, J, M, Z).
Useful for checking pay for previous tax years 2011/2012 (i.e. from 6th April 2011 up until now). Check if you are due any tax refunds.
Calculate your pay from one pay period to the next, and saving your pay profile so you there is no the need to re-enter information. Check payslips for the correct deduction of Tax and National Insurance, and other common deductions.
Salary Payroll Wage Calculator is available in English for now but translations in other languages will be made on request.