60/40 split bills: a simple compromise (UK)

60/40 is popular because it’s easy to remember and often “good enough” when incomes are slightly different. It’s less rigid than 50/50 and less fiddly than recalculating proportional shares after every pay change.

Last updated: 2025-12-17

Built by Brandon

Methodology

Use the calculator with a 60/40 split

Opens the main calculator prefilled so you can compare 60/40 vs proportional vs 50/50 and check leftovers.

No signup. Private. Links are shareable and can be reset anytime.

Use the calculator with these defaults Open the calculator

The key question: what happens to leftovers?

A split is only “fair” if it’s sustainable. The simplest way to check sustainability is to look at how much each person has left after shared costs. If 50/50 makes one person anxious every month, 60/40 can reduce that stress while keeping the admin simple.

Use the calculator to compare 60/40 against proportional (by income). If the results are close, a fixed split can be easier to maintain. If the results are far apart, proportional may be the fairer default.

Worked examples (with numbers)

Example 1: small income gap, 60/40 is enough

Incomes: A £3,200 / B £2,600 · Home £395,000 · Deposit 10%

Total shared cost: £2,753 / month

Proportional

A £1,519 · B £1,234

50 / 50

A £1,377 · B £1,377

Selected: 60 / 40 · Leftovers: A £1,548 / B £1,499

Open this scenario in the calculator Read proportional splits

Example 2: 60/40 vs proportional when incomes diverge

Incomes: A £4,300 / B £2,500 · Home £465,000 · Deposit £85,000

Total shared cost: £3,180 / month

Proportional

A £2,011 · B £1,169

50 / 50

A £1,590 · B £1,590

Selected: 60 / 40 · Leftovers: A £2,392 / B £1,228

Open this scenario in the calculator Read proportional splits

Stress test it (don’t skip this)

If 60/40 feels okay today but collapses at +1% or +2% rates, it may be the home price (or buffer) that’s the issue rather than the split. Use stress tests to see if your savings rate survives and whether one person could cover the shared cost temporarily.

Open the stress test guide

FAQ

When is 60/40 better than 50/50?

When incomes are slightly different and 50/50 leaves one person with noticeably less leftover. 60/40 can be a simple compromise without fully switching to proportional.

Should we use proportional instead?

If you want the split to track incomes automatically, proportional is cleaner. If you prefer a stable rule that doesn’t change every pay rise, 60/40 can be easier to live with.

Does 60/40 apply to mortgage only, or bills too?

Up to you. Some couples split the mortgage by income (bigger number) and split smaller bills 50/50 for simplicity. The calculator lets you compare options quickly.

What’s the best way to decide?

Pick the option that keeps both leftovers healthy and passes the stress tests (+1%, +2%, and one‑income). If two options are close, choose the one that’s simplest to maintain.