A white-tailed deer is, functionally, a walking appetite. Wildlife biologists commonly estimate that deer eat somewhere around 6–8% of their body weight in forage every day — browse, forbs, mast, grasses, and whatever your garden was unwise enough to offer. For an average 150-pound whitetail, that works out to roughly 9 to 12 pounds of green food daily, which explains a great deal about the state of suburban hostas.
This calculator lets you scale that rule of thumb across any animal and any stretch of time. Use the presets for a typical doe, a mature buck, a bull elk, or a bull moose — or type in any weight — then pick a timespan and see what the grocery bill looks like. A year of feeding one deer adds up to well over a ton of vegetation.
Deer Forage Calculator
Estimate how many pounds of forage a deer (or a bigger cervid) eats over any stretch of time.
Pick a preset or enter a weight, then press Calculate.
Estimates only. Intake varies with season, forage quality, and the animal’s condition.
How this estimate works
The math is deliberately simple: daily intake = body weight × 6% to 8%, multiplied by the number of days you choose. The low multiplier gives the bottom of the range and the high multiplier gives the top, so a 150 lb deer over 30 days shows as 270–360 lbs of forage. These percentages are the ranges most commonly cited in deer-management literature for white-tailed deer on decent habitat — they are field rules of thumb, not laboratory measurements.
Real intake moves around a lot. Deer eat hard in spring and summer when forage is lush and does are nursing fawns, pile on intake again during fall to build fat, and then deliberately eat less in winter — their metabolism slows and northern whitetails may drop to a fraction of summer intake even when food is available. Rutting bucks famously run themselves ragged and barely eat for weeks. Forage moisture matters too: 10 lbs of succulent spring browse is not the same dry-matter meal as 10 lbs of woody winter twigs.
One more honesty note baked into the tool: the 6–8% rule is calibrated to deer-sized animals. Very large cervids run relatively slower metabolisms per pound, so a 1,000 lb moose — which the calculator scores at 60–80 lbs per day — more typically eats in the 40–60 lb range in summer. The calculator flags this whenever you enter a heavyweight, and you should read the low end of the range as the realistic figure for elk and moose.
What the numbers mean for your land
Run the calculator for a year and the practical lesson jumps out: a single deer eats well over 3,000 pounds of vegetation annually, and deer do not live alone. A property holding twenty deer is supplying somewhere in the neighborhood of 30 tons of forage a year, which is why habitat quality — not winter corn piles — is what actually determines how many deer a piece of ground can carry. Biologists call that ceiling carrying capacity, and when a herd exceeds it the signs are easy to read: browse lines on the cedars, hammered food plots, and smaller-bodied deer.
It is also why wildlife agencies are increasingly wary of supplemental feeding. Dumping 50 pounds of corn into a woods where each deer needs 9–12 pounds of balanced forage a day does little for nutrition, concentrates animals in ways that spread disease, and can even harm deer whose winter digestion has shifted to woody browse. If you want to feed deer, the durable way is to grow it: improve native browse, plant mast trees, and let the 6–8% rule work on food the deer were built to eat.
Frequently asked questions
How much does a deer eat per day?
Commonly reported figures put a white-tailed deer at about 6–8% of body weight in forage daily: roughly 7–10 lbs for a 120 lb doe and 11–14 lbs for a 180 lb buck. What fills that quota changes constantly through the year — see our full breakdown of what deer eat and what white-tailed deer eat specifically for the seasonal menu.
Do deer eat more in winter or summer?
Summer, by a wide margin. Deer intake peaks when forage is abundant and nutritional demands are highest — lactating does in early summer and bucks growing antlers both eat near the top of the range. In winter, northern deer enter a semi-starvation metabolic state: activity drops, intake can fall by half or more, and they survive largely on fat reserves plus woody browse. That is also why deer movement concentrates so predictably around feeding windows — our guide to deer feeding times covers when they actually get up and eat.
How much do moose and elk eat compared to deer?
In absolute terms, far more; in relative terms, a little less. A bull elk commonly eats on the order of 20–40 lbs of forage a day and a bull moose roughly 40–60 lbs in summer — huge numbers, but a smaller percentage of body weight than a whitetail manages. Bigger bodies are more fuel-efficient per pound. Compare the animals themselves on our elk and moose species pages.