By default, it's assumed you have the standard UK 1st (85p), 2nd (66p), Large 1st (£1.29p) and Large 2nd (96p) which are are the January 2021 prices from Royal Mail (link also includes size and weight limits). Alternatively, enter the values of the stamps you have here and press submit. If you don't need all 4 values use a high number like 9999 so it won't be suggested in the calculation. If you'd like a page for a different country or values comment on my blog and I'll see what I can do.
Known limitations: Can only use up to 9 of each type of stamp (thus 36 stamps in total)
|Your target values||129|
|Size||Weight||First Class||Second Class|
|Size||Weight (up to and including)||First Class||Second Class|