This calculator will return an approximation of your redundancy entitlement, your final figure must be confirmed by employer.
Only whole years are counted.  Payment in lieu of notice (PILON) maybe applicable.  PILON maybe liable for tax and NICs.
Redundancy pay in excess of £30,000.00 is liable for tax.

This calculator is based on the following rules:

Statutory redundancy element.

0.5 wk per year worked aged under 22.
1 wk per year worked aged 22 – <41.
1.5 wks per year worked aged 41 or over.
Length of service is capped at 20 years.
Weekly pay is capped at £643.00
Maximum statutory redundancy pay
is capped at 20 x 1.5
or £19,290.00 which ever is the lowest

Service element.

1 month – 4 years 8 weeks pay.
5 years – 9 years 10 weeks pay.
10 years 12 weeks pay.
11 years 14 weeks pay.

12 years & over addition 2 weeks
per year, up to 24 years.
25+ years capped at 52 weeks.

These might not be accurate at the time of using the tool, so you should check with your employer for a definite redundancy figure.