Half Your Age Plus Seven Calculator
| Your age | Minimum (half + 7) | Maximum (double − 14) |
|---|---|---|
| 18 | 16 | 22 |
| 21 | 17.5 | 28 |
| 25 | 19.5 | 36 |
| 30 | 22 | 46 |
| 40 | 27 | 66 |
| 50 | 32 | 86 |
The rule of seven is folk arithmetic: the youngest person you should date is half your age plus seven, and by symmetry the oldest is double your age minus fourteen. A 30-year-old's range runs 22 to 46; a 40-year-old's runs 27 to 73; the two ranges only overlap when both people are at least 28 - which is the rule's quiet way of saying that under about 28, everyone is technically dating outside someone's window. It is a heuristic, not a law: no research canonizes it, and nobody has ever been arrested for violating it.
What the rule is actually good for is calibration, not permission: it packages the observation that age gaps read differently at 20 than at 40 (a 5-year gap is a third of your life at 15 and an eighth at 40) into one line you can argue with. The calculator runs it honestly in both directions and shows the acceptable window for any age - argue with the output, not with the arithmetic.
How to use
- Enter your age and theirs - the tool checks both directions of the rule at once.
- Read the verdict: inside the window (and by how much) or outside (and by how many years).
- Use the table for the window at any age - the ranges widen fast after 30, which is the rule's whole point.
Frequently asked questions
Where does the half-your-age-plus-seven rule come from?
It is usually traced to a French maxim quoted around 1900 ('demi-tonne' folklore), and it spread through early-20th-century American newspapers as advice columns picked it up. There is no research behind the specific numbers - it survives because it encodes a real observation: the relative size of an age gap shrinks as both people age.
What is the oldest I can date by the rule?
Double your age minus fourteen: 46 for a 30-year-old, 66 for a 40-year-old, 26 for a 20-year-old. The rule is symmetric by construction - if your partner passes your minimum, you pass theirs, which is why both calculators agree.
At what age do the two windows first overlap?
At 28: the youngest a 28-year-old can date is 21, and the oldest a 21-year-old can date is 28 - the first mutually closed loop. Below 28 the rule produces windows that do not touch, which is the arithmetic way of saying the early-twenties dating pool is everyone's exception.
Does research support the rule?
No - census and survey data show most couples cluster within a few years of each other regardless of the rule, and large age gaps neither predict doom nor guarantee anything by themselves. Treat the rule as a social calibration device: useful for a laugh and a sanity check, useless as an oracle.