Inspired by this xkcd comic, I built an interactive graph and calculator. You can use it to test whether your current relationship is socially acceptable or to calculate what age is too young or too old for you to date. (It might take a few seconds to load.)

The Equations

For the occasions when you need to quickly calculate whether pursuing a person of a particular age would be objectionable, here are the formulas:

So according to this, I could date a guy between the ages of 21 and 42. Personally, it’s wider than I’d probably date. My preferred minimum would be around 25 and maximum around 38, but for a rule of thumb, the calculations don’t seem too far off.

However, the older we get, the calculations start getting outrageous: A 51 year old can date an 88 year old? At 60 you can date anyone between the age of 37 and 106?  Something seems off.

How well do the formulas work?

Lucky for us, Psychology Today investigated this question by studying whether these formulas reflect people’s real preferences.

Here’s a summary of their findings:

• Men’s preferred minimum age for a partner is close to the formula’s minimum.
• Both sexes’ preferred maximum age is much younger than what the formula calculates.
• Women’s preferred minimum acceptable age is older than what the formula calculates.
• The younger you are, the more accurate the calculations.

You can read more here.

Now, who will create a more accurate calculation?

The Code

For anyone interested in learning how I built this app, here’s the code. If you know R, Shiny apps are surprisingly easy to create. Check out the tutorials at shiny.rstudio.com.

# range.R

# Calculate dating range and create text

range <- function(age){
 
     max_age <- function(x) 2*x - 14
     min_age <- function(x) .5*x + 7
 
     youngest <- min_age(age)
     oldest <- max_age(age)
 
     paste("You can safely date someone between the ages of ", 
          floor(youngest), " and ", floor(oldest), 
          ".", sep = "" )

}


# plot.R

age_plot <- function(){
     
     #set equations for lines
     top <- function(x) 2*x - 14
     bottom <- function(x) .5*x + 7
 
     #set the shading color
     color = rgb(232, 240, 237, max = 255, alpha = 225)
 
     # graph top line and titles
     curve(top, xlim = c(18,100), ylim = c(18,100),
          xlab = "your age", ylab = "your partner's age", 
          main = "Socially Acceptable Dating Range",
          col = color)
 
     # fill between lines
     top.x <- seq(0,110,.01)
     bottom.x <- seq(0,110,.01)
     top.y <- top(top.x)
     bottom.y <- bottom(bottom.x)
     x <- c(bottom.x, rev(top.x))
     y <- c(bottom.y, rev(top.y))
 
     polygon(x, y, col = color, border = color)
 
     # graph bottom line to add border again 
     # (there must be a better way!)
     par(new=TRUE)
     curve(bottom, xlim = c(18,100), ylim = c(18,100),
          xlab = "", ylab = "", col = color)
 
     # add legend
     legend(23,90, legend = "Acceptable" , 
          cex = .9, pch = 15, bty = "n", 
          col = color, pt.cex = 2)
}



# ui.R age_range

library(shiny)

shinyUI(fluidPage(

   # Sidebar with a slider input for each age
   sidebarLayout(
     sidebarPanel(
 
          br(),
          sliderInput("your_age",
               "Select your age:", min = 18,
               max = 100, value = 40
          ),
          br(),
          sliderInput("partners_age",
               "Select your partner's age:", min = 18,
               max = 100, value = 40
          ),
          br(),
 
          # Display the text
          strong("Acceptable Dating Range:"),
          textOutput("text1"),
          br()
     ),
 
     # Display the Acceptable Age Range Graph
     mainPanel(
          br(),
          plotOutput("plot")
     )
 )
))

# server.R Age Range Graph

library(shiny)
source("plot.R")
source("range.R")

shinyServer(function(input, output) {
 
 
     output$plot <- renderPlot({
 
          age_plot()
 
          # graph data point, using input from sliders
          points(input$your_age, input$partners_age, pch=20)
 
     })
 
     # Create text using input from your_age slider
     output$text1 <- renderText({
          range(input$your_age)
 
     })
})