| Category | kg/year | t/year | Monthly pace | Gross share | Copy |
|---|---|---|---|---|---|
| {{ row.label }} | {{ formatNumber(row.kg, 0) }} | {{ formatNumber(row.kg / 1000, 2) }} | {{ formatNumber(row.monthlyKg, 0) }} | {{ row.key === 'offsets' ? '—' : `${formatNumber(row.share, 1)}%` }} | |
| Gross before offsets | {{ formatNumber(gross_kg, 0) }} | {{ formatNumber(gross_kg / 1000, 2) }} | {{ formatNumber(gross_kg / 12, 0) }} | 100% | |
| Net after offsets | {{ formatNumber(total_kg, 0) }} | {{ formatNumber(total_kg / 1000, 2) }} | {{ formatNumber(total_kg / 12, 0) }} | {{ budget_kg > 0 ? `${formatNumber(coverage_pct, 1)}% of budget` : '—' }} | |
| Chosen budget | {{ formatNumber(budget_kg, 0) }} | {{ formatNumber(budget_kg / 1000, 2) }} | {{ formatNumber(budget_kg / 12, 0) }} | {{ budget_kg > 0 ? `${formatNumber(coverage_pct, 1)}% used` : 'No target' }} | |
| {{ gap_kg <= 0 ? 'Under budget by' : 'Over budget by' }} | {{ formatNumber(Math.abs(gap_kg), 0) }} | {{ formatNumber(Math.abs(gap_kg) / 1000, 2) }} | {{ formatNumber(Math.abs(gap_kg) / 12, 0) }} | — |
| Lane | Budget | Current result |
|---|---|---|
| {{ lane.label }} {{ lane.badgeText }} | {{ formatNumber(lane.targetKg / 1000, 2) }} t | {{ lane.resultText }} |
| Category | Current | Plan lens | Budget impact | Notes |
|---|---|---|---|---|
| {{ row.label }} | {{ formatNumber(row.kg / 1000, 2) }} t | {{ row.planLens }} | {{ row.impactText }} | {{ row.note }} |
A personal carbon budget is a way to turn climate goals into a household-scale planning question: how much warming impact does your current lifestyle add over a year, and which activities are using up the room fastest? That question matters because the same annual total can come from very different patterns of living, which means the best next step is rarely the same for everyone.
This analyzer estimates annual CO2e from home energy, transport, diet, other annual add-ons, and optional offsets, then compares the result with a budget lane you choose yourself. It is useful when you want a practical annual carbon footprint budget planner rather than a formal corporate inventory, because it shows both the headline total and the underlying drivers that made it.
The built-in planning lanes of 2.0, 3.0, and 5.0 tonnes per year are reference lanes inside this estimator, not official personal entitlements. They work best as anchors for judgment. If your result is above the lane you chose, the useful question becomes whether the pressure is coming from flights, a carbon-heavy grid, heating fuel, high car use, diet assumptions, or a simple input mistake such as dividing a personal utility number twice.
The result panel is built around that planning job. Net Annual Footprint gives the yearly total after offsets. Budget usage and Runway show how fast the chosen target is being consumed. Top source, Budget Ledger, Budget Levers, Source Mix, and Budget Runway keep the gross activity drivers visible so the budget comparison does not hide what actually needs attention.
Because climate budgeting depends heavily on assumptions, this kind of estimate is strongest when you use the best local numbers you have and treat the result as a planning aid. It is not a certified lifecycle assessment, tax disclosure, or carbon-accounting standard on its own.
The calculation follows a simple structure. Home electricity, natural gas, and heating oil are annualized from monthly inputs. Car travel is modeled either as an internal-combustion path using miles, fuel economy, and a fuel factor, or as an EV path using miles, electricity consumption, and the chosen grid factor. Flights and public transit use annual passenger distance multiplied by per-distance factors. Diet is converted from a daily footprint estimate into a yearly total, and a direct annual field catches anything else you want to add.
Those source totals are grouped into home energy, transport, and lifestyle emissions. Offsets are then subtracted once, after the gross total is built. That separation is important. Gross categories explain what is driving the footprint, while offsets only change the net comparison against the budget. The analyzer therefore keeps source ranking and net budgeting as related but different views.
Electricity = monthly kWh x 12 x grid factor / household share
Car (ICE) = annual miles / occupancy / mpg x fuel factor
Car (EV) = annual miles / occupancy x kWh per 100 miles / 100 x grid factor
Flights = annual km x flight factor x non-CO2 multiplier
Diet = daily diet estimate x 365
Net Annual Footprint = gross total - offsets
| Setting | Built-in options | What each option does |
|---|---|---|
| Planning lane | 2.0 t, 3.0 t, 5.0 t, or custom | Sets the annual comparison target used by Budget usage, Runway, and the lane table. |
| Grid profile | 0.2, 0.4, 0.6 kg/kWh, or custom | Changes electricity emissions directly and also changes the EV path because EV charging uses the same grid factor. |
| Diet profile | 1.5, 2.0, 3.0, 5.0, 6.0 kg/day, or custom | Converts the chosen diet pattern into a daily CO2e estimate that becomes a yearly total. |
| Flight uplift | Non-CO2 multiplier from 1.0x to 3.0x | Raises the climate impact assigned to flights to reflect extra high-altitude warming effects beyond direct fuel burn alone. |
The advanced controls are not decorative. They materially change the estimate. Choosing Shared household bills divides only home-energy totals across residents. It does not divide flights, diet, public transit, or other emissions. Car occupancy is separate and only changes the personal share of car travel. That means the most important modeling choices are often not the headline numbers themselves, but the assumptions about what counts as your personal share.
The output set mirrors those mechanics. Budget Ledger lists category totals, monthly pace, and gross share. Budget Levers translates the current gap or spare room into activity-equivalent changes. Source Mix visualizes the gross breakdown. Budget Runway spreads the current annual pace evenly across twelve months, and JSON packages the inputs, summary, categories, planning lanes, levers, recommendations, and monthly series into one exportable record.
Start with the most uncertain category, not the easiest one. For many people that is flights, home-energy sharing, or the grid factor rather than transit or miscellaneous emissions. If one input is dominating the total, improving that assumption usually does more for accuracy than polishing small categories.
Choose a planning lane that matches the question you are asking. A tighter lane is useful when you want to stress-test a low-carbon lifestyle. A looser lane is useful when you want to see how far current habits still are from a more ambitious path. If you already have a personal or project target, switch to custom and use that instead of forcing your life into one of the built-in lanes.
Read the result in two passes. First, look at Net Annual Footprint, the budget badge, and Budget usage to see where you stand. Then switch immediately to Top source, Budget Ledger, and Budget Levers to see why. That second pass matters because two results that are both "over budget" can imply very different actions. One may be a flight problem. Another may be a heating and grid problem. Another may simply be a diet preset that is too high or too low for your actual pattern.
Use offsets carefully. In this analyzer they are a direct annual subtraction from the gross total, so they can improve the budget comparison quickly. They do not reduce the gross emissions shown in Source Mix or change the category that appears as Top source. That is a sensible planning choice because a large offset entry should not hide the underlying activity that is still producing the emissions.
Net Annual Footprint, Budget usage, and Top source, then use Budget Ledger and Budget Levers to decide which category deserves attention first.JSON snapshot.The status badge is determined entirely by the relationship between the net annual total and the chosen budget. That means the wording is simple on purpose. It is there to classify the gap, not to tell you whether your lifestyle is globally fair, complete, or permanently optimized.
| Status shown | Rule used here | Best first reading |
|---|---|---|
| Comfortably under | Net total is within budget and Budget usage is below 75%. |
You have clear spare room against the chosen lane, but the biggest category is still worth watching. |
| Within budget | Net total is within budget and Budget usage is 75% or higher. |
You are still inside the target, but there is less margin for extra travel, heating, or other growth. |
| Slightly over | Net total is above budget, but Budget usage is no more than 125%. |
The gap may be solvable with one strong lever or a small set of coordinated reductions. |
| Over budget | Budget usage is above 125%. |
The gap is large enough that the result usually needs more than one adjustment, or a rethink of the chosen lane and assumptions. |
Runway is a pacing view, not a seasonal forecast. The chart spreads the current annual pace evenly across twelve months, so it is best for understanding pressure on the budget rather than predicting exactly which month your real-life footprint will spike. If your home heating or flying is seasonal, the real year will be lumpier than the line suggests.
The most useful cross-check is whether Top source feels believable. If the result says flights dominate, but you barely fly, check the flight distance or multiplier. If electricity dominates an EV-heavy result, check the grid factor and charging assumptions. If the number looks strangely low, review household splitting and offsets before trusting the headline.
Choose the 3.0 t Transition lane. Enter 150 kWh/month of electricity, no gas or heating oil, no personal car, 10,000 km/year of flights, 1,000 km/year of public transit, a 2.0 kg/day diet estimate, and 200 kg/year of other emissions. With the default flight factor and no offsets, Net Annual Footprint comes out to 3.20 tCO2e.
That produces Budget usage of about 107%, so the badge becomes Slightly over. Top source is Flights, not electricity, and the gap is only 0.20 tCO2e. In this kind of result, Budget Levers is telling you that a modest reduction in flight distance could close the whole gap without touching every category.
Keep the same 3.0 t lane, but model a different life: 180 kWh/month of electricity on a personal basis, no gas, 5,000 EV miles/year at 28 kWh/100 mi, 800 km/year of flights, 2,500 km/year of public transit, a 2.0 kg/day diet estimate, 150 kg/year of other emissions, and 150 kg/year of offsets. The gross total is 2.55 tCO2e and the net result falls to about 2.40 tCO2e.
Now the badge reads Within budget, Budget usage is roughly 80%, and Offsets impact shows 0.15 tCO2e. Even so, Top source remains electricity because the source ranking stays gross-focused. That is a good reminder that being under budget does not mean the largest category stops mattering.
Suppose you already entered your own electricity share as 180 kWh/month, but you accidentally leave Home-energy input on Shared household bills and set Household people to 4. Add 500 km/year of public transit, a 3.0 kg/day diet estimate, and 100 kg/year of other emissions. The analyzer will divide the electricity again, which drops Net Annual Footprint to about 1.44 tCO2e and Budget usage to roughly 48%.
Switch Home-energy input to Already my personal share without changing the rest. The electricity category jumps back to its real level, Net Annual Footprint rises to about 2.08 tCO2e, and Budget usage moves to roughly 69%. The status is still Comfortably under, but the corrected result is far more believable and much more useful for planning.
No. They are built-in comparison lanes used by this analyzer. They are useful for planning, but they are not universal personal quotas and they do not override your own household, project, or policy target.
No target?That status appears when the annual budget is zero or not effectively set. The gross calculation still works, but Budget usage and Runway need a positive annual target. Pick one of the built-in lanes or enter a custom budget to restore the full comparison.
Source Mix and Top source stay the same after I entered offsets?Because offsets only change the net total. The visual source ranking stays based on gross activity emissions so that one large offset entry does not hide which category is actually producing most of the footprint.
Household people?That control divides only home electricity, gas, and heating oil across residents. If you already entered your own share of the bill, leave the home-energy mode on Already my personal share. Otherwise the tool will divide those numbers again and understate the home-energy total assigned to you.
Routine calculation stays in the browser and this estimator has no tool-specific backend. The exports such as CSV, DOCX, chart images, chart CSV, and JSON are generated from the client-side result.