Universal credit (UC) is a means-tested benefit. The amount of UC you get depends on your needs (your ‘maximum amount’) and how much income and capital you (and your partner) have. If you are severely disabled and transferred to UC from your old means-tested benefit under the natural migration process, you may also get a transitional amount (known as a ‘transitional SDP amount’) included in your UC. The amount you get is calculated over a monthly ‘assessment period’. As your income increases, your UC award is reduced.
The most accurate way to calculate your entitlement is with a manual calculation. This can appear a little daunting at first but it's a fantastic way to ensure your calculation is accurate and helps with understanding UC, meaning you may be able to spot any errors that may occur in your claim at a later date.