green calculator

Composting Bin Size Calculator

Size a compost bin from your household size, weekly organic waste, and browns-to-greens ratio.

Recommended Bin Size = Weekly Input (greens + browns, by volume) × Turnover Weeks × 0.7 compaction factor. Example: a household of 4 producing 17 lb of weekly greens at a 2:1 browns ratio, emptied every 8 weeks, needs about 5.7 cubic feet.

Formula Verified by Dr. Olivia Martinez, PhD

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Household Sizepeople

Food Scraps per Personlb/week

Weekly Yard Wastelb/week

Turnover Timeweeks

Browns : Greens Ratio (by volume): 1

Results

Recommended Bin Size

5.7 cu ft (43 gal)

Weekly Greens (food + yard waste)17.0 lb

Total Weekly Input (greens + browns)7.6 gal

Tip

Re-run it if your household size changes, you start adding yard waste, or you switch how often you empty the bin.

Formula

Bin sizing formula

Weekly Greens (lb) = Household Size × Food Scraps per Person + Yard Waste
Total Weekly Input (gal) = Weekly Greens (lb) × 0.15 gal/lb × (1 + Browns Ratio)
Recommended Bin Size = Total Weekly Input × Turnover Weeks × 0.7 (compaction factor)

The 0.7 compaction factor accounts for material settling and starting to break down before the bin is emptied or turned, so the bin doesn't need to hold the full undecomposed peak volume. This is an estimate — bulkier browns (whole leaves, straw) take up more air space than this model assumes.

Step by step

How the calculation works

1Enter your household size and an estimate of weekly food scraps per person (adjust to match your actual kitchen waste).
2Add any weekly yard waste like grass clippings or trimmings you plan to compost alongside food scraps.
3Set your turnover time — how many weeks of material the bin holds before you empty, harvest, or move it to a second bin.
4Set your browns-to-greens ratio by volume (2:1 to 3:1 is the standard range) to see the total bin size needed.

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green calculator

Composting Bin Size Calculator

Size a compost bin from your household size, weekly organic waste, and browns-to-greens ratio.

Formula Verified by Dr. Olivia Martinez, PhD

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Household Sizepeople

Food Scraps per Personlb/week

Weekly Yard Wastelb/week

Turnover Timeweeks

Browns : Greens Ratio (by volume): 1

Results

Recommended Bin Size

5.7 cu ft (43 gal)

Weekly Greens (food + yard waste)17.0 lb

Total Weekly Input (greens + browns)7.6 gal

Tip

Re-run it if your household size changes, you start adding yard waste, or you switch how often you empty the bin.

Summary

Key output metrics

Recommended Bin Size

5.7 cu ft

43 gallons

Weekly Greens

17.0 lb

2.5 gal before browns

Total Weekly Input

7.6 gal

Includes 2:1 browns

D3 visualization

Your Bin vs. Common Bin Sizes (cu ft)

Where your recommended size lands against everyday composting bin benchmarks.

Guide

How to understand and use this calculator

Quick Answer — How Big a Compost Bin Do You Need?

Weekly Greens (lb) = Household Size × Food Scraps per Person + Yard Waste. Start from how much nitrogen-rich "green" material (food scraps, fresh trimmings) your household actually produces each week.

Convert that weight to volume and add the browns (dry leaves, cardboard, straw) that need to go in alongside it — the standard range is 2 to 3 parts browns to 1 part greens by volume: Total Weekly Input (gal) = Weekly Greens (lb) × 0.15 × (1 + Browns Ratio).

Finally, size the bin for however many weeks of material it holds before you empty or turn it, applying a compaction factor since material starts settling and breaking down well before that point: Recommended Bin Size = Total Weekly Input × Turnover Weeks × 0.7.

How to Use This Calculator

Enter your household size and a weekly food-scraps-per-person estimate (adjust to match your own kitchen — a household that composts all fruit and vegetable trim will produce more than one that only composts occasional scraps). Add any weekly yard waste, set how many weeks the bin holds material before you empty it, and set your browns-to-greens ratio.

Worked example: a household of 4, each producing about 3 lb of food scraps per week, plus 5 lb of weekly yard waste, emptying the bin every 8 weeks, using a 2:1 browns-to-greens ratio. Weekly greens: (4 × 3) + 5 = 17 lb, which converts to 17 × 0.15 = 2.55 gal. Adding browns at 2:1: 2.55 × (1 + 2) = 7.65 gal total weekly input. Over an 8-week turnover: 7.65 × 8 = 61.2 gal raw, ×0.7 compaction = 42.8 gallons, about 5.7 cubic feet — comfortably sized by a mid-size tumbler or a compact stationary bin.

A Second Example: A Small Household, Shorter Cycle

A 2-person household composting only kitchen scraps (no yard waste), 2.5 lb per person per week, emptying every 6 weeks, using a richer 3:1 browns ratio. Weekly greens: 2 × 2.5 = 5 lb, converting to 5 × 0.15 = 0.75 gal. Adding browns at 3:1: 0.75 × 4 = 3.0 gal total weekly input. Over 6 weeks: 3.0 × 6 = 18 gal raw, ×0.7 compaction = 12.6 gallons, about 1.7 cubic feet — small enough for a countertop-adjacent bin or a small balcony tumbler, well under the 27-cubic-foot minimum a hot compost pile would need.

Sizing for Volume vs. Sizing for Heat

This calculator sizes a bin around how much material you'll realistically accumulate — a practical "will it fit" question. That's a different question from what a hot composting pile needs to self-heat: a hot pile needs enough thermal mass to hold its own heat, which is why guides commonly cite a 3×3×3 ft (27 cubic foot) minimum pile size regardless of weekly input. If your household's weekly waste volume computes to a bin much smaller than that and you specifically want a fast, hot compost cycle rather than a slower cold compost, plan for the 27-cubic-foot minimum instead of the volume-only number above — you may need to accumulate material or combine with a neighbor's yard waste to reach it.

Common Bin Sizes, for Reference

It helps to know where your number lands against what's actually sold. A countertop caddy holds roughly a quarter cubic foot — a day or two of scraps at most, meant to be emptied into an outdoor bin, not to hold a full cycle. Small tumblers run around 4-6 cubic feet, suited to a single person or couple with a short turnover. Mid-size stationary bins (wire, wood, or plastic) commonly run 8-13 cubic feet, a comfortable fit for most 3-5 person households on a 6-10 week turnover. Beyond that, dedicated hot-composting setups target the 27-cubic-foot (3×3×3 ft) minimum discussed above.

If your calculated result falls between two common sizes, it's generally safer to round up — an oversized bin just has some empty headroom, while an undersized one means overflow, more frequent emptying than planned, or a pile too small to heat up if you wanted a hot cycle.

Limitations

This is a volume-planning estimate, not a precise engineering calculation. The 0.15 gal/lb density factor is an average — bulkier browns like whole dry leaves or straw take up more air space per pound than this model assumes, so bins heavy on bulky browns may need to run larger than the raw number suggests. Actual decomposition speed (and therefore how much the compaction factor should really discount the raw volume) varies with climate, turning frequency, and moisture, so treat the recommended size as a starting point and size up if you're unsure.

Related Calculators

Once your bin is sized, the Compost Impact Calculator estimates the CO2e avoided, finished compost volume, and nutrient value your composting actually produces from the same weekly waste inputs. The Garden Fertilizer NPK Calculator helps balance finished compost against other amendments to hit a target nutrient ratio, the Food Waste Impact Calculator quantifies what food waste costs before it ever reaches the bin, and the Recycling Impact Calculator covers the landfill-diversion side of your household waste stream.

Related concepts

Greens vs. browns

Nitrogen-rich moist materials (food scraps, fresh trimmings) versus carbon-rich dry materials (leaves, cardboard, straw).

Turnover time

How many weeks of accumulated material a bin holds before it's emptied, harvested, or moved to a second bin.

Hot vs. cold composting

Hot composting uses enough thermal mass to self-heat and decompose faster; cold composting is slower and doesn't require a minimum pile size.

Frequently Asked Questions

What's the difference between this calculator and the Compost Impact Calculator?+

This one answers "how big a bin do I need" from your household's waste volume. The Compost Impact Calculator answers "what does composting that waste actually produce" — CO2e avoided, finished compost weight, and nutrient value. Use this one first to size your setup, then that one to see the payoff.

What's a typical browns-to-greens ratio?+

2:1 to 3:1 by volume (browns to greens) is the standard range cited by most composting guides. More browns generally means a less smelly, better-aerated pile; too few browns can lead to a wet, compacted, odorous bin.

Why does the calculator apply a compaction factor?+

Material doesn't sit at full, undecomposed volume the whole time it's in the bin — it settles and starts breaking down from the moment it's added. Sizing for the full raw accumulated volume over the whole turnover period would over-size the bin; the compaction factor (0.7) reflects volume already lost to settling and early decomposition.

My result seems small — should I still buy a bigger bin?+

If you want a hot, fast composting cycle, yes — hot piles need roughly 27 cubic feet (a 3×3×3 ft pile) of thermal mass regardless of your weekly waste volume, as noted above. If you're fine with a slower cold-compost cycle, sizing to this calculator's volume-based recommendation is reasonable.

Does yard waste count as green or brown material?+

It depends on the specific material — fresh grass clippings and green trimmings act as greens, while dried leaves and woody prunings act as browns. This calculator treats the yard waste you enter as part of the green/moist input; add dry leaves or straw separately as part of your browns ratio.

How often should I empty or turn my bin?+

It depends on your setup and goals — a hot, actively turned pile can finish in as little as 4-8 weeks, while a passive cold-compost bin can take 6-12 months. Set the turnover weeks input to match your actual routine for the most accurate size.

Formula

Bin sizing formula

Weekly Greens (lb) = Household Size × Food Scraps per Person + Yard Waste
Total Weekly Input (gal) = Weekly Greens (lb) × 0.15 gal/lb × (1 + Browns Ratio)
Recommended Bin Size = Total Weekly Input × Turnover Weeks × 0.7 (compaction factor)

Step by step

How the calculation works

1Enter your household size and an estimate of weekly food scraps per person (adjust to match your actual kitchen waste).
2Add any weekly yard waste like grass clippings or trimmings you plan to compost alongside food scraps.
3Set your turnover time — how many weeks of material the bin holds before you empty, harvest, or move it to a second bin.
4Set your browns-to-greens ratio by volume (2:1 to 3:1 is the standard range) to see the total bin size needed.

Related guides

Learn more about this calculation

Guide