Parental Career Sacrifice Calculator

Take a UK mother on £50,000 who took 5 years out and returned on £30,000. The salary gap of £20,000 over 5 years is £100,000 in direct lost earnings alone. On top, she missed 5 years of employer pension contributions (around 5 percent, so £2,500 a year) compounding to retirement at 67; if she took the break at age 30, those missed contributions compound for 32 years and tally roughly £40,000 to £60,000 in lost retirement value. Add lost progression (the 3.5 percent annual raises she was on track for) and the motherhood penalty (a documented 4 percent per child wage drop that persists), and the realistic total is £200,000 to £400,000.

The numbers feel huge because they are. The calculator is not designed to make anyone feel guilty; it is designed to put a real figure on what UK and US policy already knows. The motherhood penalty is structural, not personal. Countries with longer paid parental leave (Germany 14 weeks at 100 percent, Sweden 480 days shared) close the gap noticeably; the UK offers 39 weeks mostly unpaid at the £187.18 a week statutory rate, the US has no federal paid leave guarantee at all.

Pension losses scale brutally with how young you were when the break happened. A break at age 30 with 5 percent employer contributions on a £50,000 salary loses around £40,000 to £60,000 in compound growth by age 67 (using a 5 percent annual return assumption). The same break at age 38 only loses about £25,000 to £35,000, because there are fewer years left for the missed pot to grow. This is why "I will go back when the kids are in school" sounds reasonable but quietly costs an extra £15,000 to £25,000 in retirement money compared to a shorter break at the same total cost.

If the calculator returns a number that scares you, the practical responses are: top up your own contributions when you do return (most employers match up to 5 to 8 percent), claim child benefit even if you do not need the cash because it counts as a National Insurance credit toward your state pension, and look at SIPPs or ISAs in the lower-earning years. None of this fixes the structural issue, but it slows the bleeding.

Real research (Lundborg, Plug and Rasmussen 2017, Kleven 2019) finds mothers' wages drop by roughly 4 percent per child compared to childless peers, and the gap persists for the rest of the working life. The calculator applies this 4 percent per child to the years remaining from your return age to 67. For 2 children that is 8 percent off your post-return salary every year for 25 to 35 years; on a £30,000 returner's salary that is £2,400 a year, or roughly £75,000 over a 30-year career.

Edge case: many mothers return part-time, which makes the gap look larger because the comparator is full-time wages. Run the calculator with your actual current full-time-equivalent salary rather than your part-time pay packet to get the cleaner number. The [emotional labour calculator](/emotional-labour-calculator) and the [stay at home mum calculator](/stay-at-home-mum-calculator) capture the unpaid work that came with the break, which is a separate (and equally real) figure.