We have been measuring Best Days wrong. For years, we have used the wrong units — dollars spent, miles travelled, photographs taken, followers gained. We have confused spectacle with substance, and expense with value. The private jet to Monaco scores beautifully on Instagram. It scores terribly on what actually matters.
The Net Best Day Index is our attempt to do the maths properly. It borrows its logic from the Happy Planet Index — the New Economics Foundation's elegant argument that a good life must be measured not just by how long and happy it is, but by how lightly it treads on the world that makes it possible. We apply that same logic to a single day.
A Best Day Ever, properly defined, is a day that is net positive. Not just for you. For the people around you, for the community you moved through, for the environment you borrowed, and for the strangers who will inherit whatever you left behind. A day that takes more than it gives is not a Best Day Ever. It is a debt.
The equation is simple. The implications are not.
— Advertisement —
THE FRAMEWORK
THE EQUATION
How good the day felt for you. Subjective, honest, self-reported. Not what you told Instagram — what you actually felt.
The positive effect on people around you. Did you make someone feel seen? Support a local artisan? Strengthen a relationship? Visiting a lonely grandparent scores 10. Ignoring the waiter scores 0.
Did the day add something to the cultural fabric? Local art, music, food, craft, knowledge. Money that stays in the community. Streaming Netflix alone scores 0. A farmers market morning scores 9.
Carbon and ecological impact. Walking scores 0. A short drive scores 2. A long-haul flight scores 6–8. A private jet scores 10. The atmosphere does not care how much you enjoyed the view.
Did the day damage anyone else's experience? Noise, congestion, crowding a fragile natural space, littering, disturbing wildlife. Most good days score 0 here. Some days score more than their owners realise.
Did the day require or reinforce inequality? A walk in the park is free and accessible to anyone. A Michelin three-star tasting menu is not. The NBDI does not punish spending. It notes when a day is structurally unavailable to most of humanity.
How much of the day was actually lived? Fully present, no screens, no dead time scores 2.0. Mostly passive, distracted, or spent in transit scores 0.5. A day spent half-watching your phone while your child plays in the garden is not a Best Day. It is a missed one.
Why We Multiply the Good
and Add the Bad
The numerator multiplies P, S, and C together rather than adding them. This is deliberate. A day that scores 10 on personal joy, 10 on social ripple, and 10 on community contribution is not thirty times better than a day that scores 1 on each. It is a thousand times better. Joy that radiates outward is exponentially more valuable than joy that stays inside.
The denominator adds E, H, and I rather than multiplying them. A day with one catastrophic cost — say, a private jet flight — is bad, but it is not infinitely worse than a day with three moderate costs. The damage accumulates linearly. The joy compounds geometrically. This asymmetry is the point.
"The best days are rarely the most expensive ones. They are the days when we are present, connected, and leaving something behind that is better than what we found."
The D divisor — Duration Efficiency — is the quiet enforcer. A day spent in first class on a twelve-hour flight might score high on personal comfort, but if you spent it watching films and ignoring your travel companion, D drops to 0.6, and the whole equation suffers. Presence is not a soft variable. It is the denominator.
THE NUMBERS
Five Days. The Maths.
| THE DAY | P | S | C | E | H | I | D | NBDI |
|---|---|---|---|---|---|---|---|---|
| Visit Grandma | 8 | 10 | 6 | 2 | 0 | 0 | 1.8 | 265.6 |
| Farmers Market Morning | 7 | 8 | 9 | 1 | 0 | 1 | 1.6 | 313.8 |
| Walk in the Park | 7 | 6 | 4 | 0 | 0 | 0 | 1.7 | 98.8 |
| Whistler Bike Park | 10 | 7 | 5 | 5 | 1 | 4 | 1.9 | 178.9 |
| Private Jet to Monaco | 9 | 3 | 2 | 10 | 4 | 10 | 1.5 | 20.0 |
P = Personal Joy · S = Social Ripple · C = Community Contribution · E = Environmental Cost · H = Harm to Others · I = Inequality Cost · D = Duration Efficiency
The Score Bands
A day that made the world measurably better
A genuine Best Day Ever
A solid, positive day
Fine, but room to grow
You were there, but barely
You took more than you gave
NBDI: 313.75 — LEGENDARY
The Farmers Market
Morning
You walked there. You talked to the person who grew the tomatoes. You ran into a neighbour and stood in the sun for twenty minutes talking about nothing important and everything that matters. You bought honey from a beekeeper who explained the difference between clover and wildflower. You went home with a bag full of things that were alive last week.
The NBDI for this morning is 313.75. Legendary. The carbon cost was zero. The harm to others was zero. The inequality cost was one — a modest amount of money, but not nothing. The community contribution was nine. The social ripple was eight. You were present for all of it.
NBDI: 98.8 — DECENT
A Walk in the Park
with Your Dog
Simple, grounding, good. The dog is thrilled. You nodded at a few strangers. You used a public park — which is a form of civic participation, even if you did not think of it that way. You walked from home. The carbon cost was zero.
The NBDI is 98.8 — Decent. It scores lower than the farmers market not because it was a worse day, but because the social and community contributions were more modest. You were mostly alone. That is fine. Not every day needs to be a community event. But the equation notes the difference.
— Advertisement —
The Uncomfortable Truth
The private jet to Monaco scores 20. The visit to grandma scores 265. The farmers market scores 313. The walk in the park scores 98. This is not a coincidence. The equation is designed to reveal what we already know but rarely admit.
The NBDI does not punish adventure or travel. Whistler Bike Park scores 178.9 — a genuinely excellent day, even with the drive and the lift pass. It punishes waste — the kind of waste that comes from treating the world as a backdrop for your own satisfaction, rather than a place you are briefly, gratefully, borrowing.
It also punishes absence. A day spent in the most beautiful place on earth, staring at your phone, scores half what it should. The D variable is the equation's conscience. It asks the question that no other index asks: were you actually there?
"The best days are not the ones you remember because of what you spent. They are the ones you remember because of who you were."
The NBDI is not a moral judgement. It is a mirror. Use it accordingly.
INTERACTIVE
CALCULATE YOUR DAY
Adjust the sliders to score your day. Load a preset to see the framework in action.
A solid, positive day. Room to grow, but nothing to be ashamed of.
How good did the day feel for you, honestly?
Positive effect on people around you
Did you add something to the cultural fabric?
Carbon and ecological impact of the day
Did the day damage anyone else's experience?
Did the day require or reinforce inequality?
Fully present and engaged vs. distracted, passive, or mostly in transit
Maximum theoretical NBDI: 500 (10×10×10 − 0, ÷ 2.0) · Minimum: −60 · Average good day: ~200
SOURCES & METHODOLOGY
GERALD'S NOTE
I built this equation because I was tired of being impressed by the wrong things. I have had days on private jets that I barely remember. I have had mornings at the farmers market that I will carry for the rest of my life. The maths was always there. I just needed to write it down.
The NBDI is not a perfect instrument. The variables are subjective. The weights are debatable. The D divisor in particular will annoy people who believe that rest is its own form of presence — and they are not entirely wrong. But the framework is honest about what it is measuring, and it measures the things that matter.
Go visit your grandmother. Walk to the market. Ride your bike with your friends. Leave the place better than you found it. Be present for all of it.
Best Day Ever.
— Gerald Shaffer, Editor, Just Gerald Magazine
— Advertisement —
NET BEST DAY INDEX
SEE HOW YOUR DAY RANKS
The NBDI Leaderboard ranks reader-submitted Best Days Ever by score. Submit yours and claim a spot.