Buy vs Build a PC Calculator: Which Costs Less Per Year?

Buy or build: the yearly cost decides

On the defaults — a $1,200.00 prebuilt PC over 5 years, $900.00 of parts, 6 hours of building at $25.00 an hour, and a 5-year build life — the prebuilt cost is $240.00 a year ($1,200.00 ÷ 5), the build cost is $210.00 a year (($900.00 + $150.00) ÷ 5), the gap is −$30.00, and building wins by $30.00 a year.

Five things about the model are worth stating plainly. First, the prebuilt cost per year is the prebuilt PC price divided by the years you expect it to last — $1,200.00 ÷ 5 = $240.00. Second, the build cost per year is the parts cost plus your build time’s value plus tools, divided by the years you expect the build to last — ($900.00 + $150.00 + $0.00) ÷ 5 = $210.00. Third, the gap is the build yearly cost minus the prebuilt yearly cost — $210.00 − $240.00 = −$30.00 — and a negative gap means building wins. Fourth, the winner is decided from the rounded gap, and a gap of exactly $0.00 is a tie. And fifth, the sticker price misleads — the $900.00 of parts looks like 25% less than the $1,200.00 prebuilt, but 6 hours of your time at $25.00 an hour is $150.00, and that closes most of the gap; all listed in Accuracy & limitations.

This calculator is part of the X vs Y comparisons library — the same compare-both-sides format as the lease vs buy laptop and buy new vs used car calculators.

The worked example, line by line

Setup: $1,200.00 prebuilt PC, 5 years, $900.00 of parts, 6 hours of building at $25.00 an hour, $0.00 of tools, 5-year build life.

Line 1 — the prebuilt side. The prebuilt cost per year is $1,200.00 ÷ 5 = $240.00.

Line 2 — the build time’s value. Your build time is worth 6 × $25.00 = $150.00.

Line 3 — the build side. The build cost per year is ($900.00 + $150.00 + $0.00) ÷ 5 = $210.00.

Line 4 — the gap. The gap is $210.00 − $240.00 = −$30.00 — negative, so building wins by $30.00 a year.

Every branch, checked

Parts $1,100.00: Prebuilt $1,200.00, 5 years, parts $1,100.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $250.00/year, build time $150.00, gap $10.00 (BUYING wins by $10.00/year) — $1,100.00 of parts makes the build $250.00 a year — buying wins by $10.00.

Prebuilt $900.00: Prebuilt $900.00, 5 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $180.00/year, build $210.00/year, build time $150.00, gap $30.00 (BUYING wins by $30.00/year) — A $900.00 prebuilt costs only $180.00 a year — buying wins by $30.00.

Build lasts 7 years: Prebuilt $1,200.00, 5 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 7 years: prebuilt $240.00/year, build $150.00/year, build time $150.00, gap -$90.00 (BUILDING wins by $90.00/year) — A build that lasts 7 years costs only $150.00 a year — building wins by $90.00.

Prebuilt lasts 3 years: Prebuilt $1,200.00, 3 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $400.00/year, build $210.00/year, build time $150.00, gap -$190.00 (BUILDING wins by $190.00/year) — A prebuilt that only lasts 3 years costs $400.00 a year — building wins by $190.00.

Prebuilt lasts 7 years: Prebuilt $1,200.00, 7 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $171.43/year, build $210.00/year, build time $150.00, gap $38.57 (BUYING wins by $38.57/year) — A prebuilt that lasts 7 years costs $171.43 a year — buying wins by $38.57.

Parts $700.00, 10 hours at $50.00 an hour: Prebuilt $1,200.00, 5 years, parts $700.00, 10 hours at $50.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $240.00/year, build time $500.00, gap $0.00 (tie) — $700.00 of parts and 10 hours at $50.00 an hour is a tie — $240.00 a year on both sides.

The reverses, worked backwards

Parts cost for an exact tie: $1,050.00 — the exact parts cost is 1050.0000. At $1,050.00 the build cost is $240.00 a year and the gap is $0.00 — an exact tie. $1,049.99 and $1,050.01 both give $240.00 a year after rounding. The star is DOLLARS.

Prebuilt price for an exact tie: $1,050.00 — the exact prebuilt price is 1050.0000. At $1,050.00 the prebuilt cost is $210.00 a year and the gap is $0.00 — an exact tie. $1,049.99 and $1,050.01 both give $210.00 a year after rounding. The star is DOLLARS.

Build lifespan where the winner flips: 4 years is the longest build lifespan where buying still wins (build $262.50 a year, BUYING by $22.50); 5 years is the shortest build lifespan where building wins (build $210.00 a year, BUILDING by $30.00). The flip happens between 4 and 5 years — 3 years gives a build cost of $350.00 a year (BUYING by $110.00). The star is YEARS.

Parts cost for BUILDING to win by exactly $50.00/year: $800.00 — the exact parts cost is 800.0000. At the displayed $800.00 the build cost is $190.00 a year and the gap is −$50.00 — BUILDING wins by exactly $50.00. $799.99 and $800.01 both give $190.00 a year after rounding. The star is DOLLARS.

Prebuilt price for BUYING to win by exactly $100.00/year: $550.00 — the exact prebuilt price is 550.0000. At the displayed $550.00 the prebuilt cost is $110.00 a year and the gap is $100.00 — BUYING wins by exactly $100.00. $549.99 and $550.01 both give $110.00 a year after rounding. The star is DOLLARS.

Build time for an exact tie (at $25.00 an hour): 12 hours (time value $300.00) — the exact build time is 12. At 12 hours the build cost is $240.00 a year and the gap is $0.00 — an exact tie. 11.99 hours gives a build cost of $239.95 a year (BUILDING by $0.05); 12.01 hours gives $240.05 a year (BUYING by $0.05). The star is HOURS.

What the defaults assume

The defaults are a $1,200.00 prebuilt PC over 5 years, $900.00 of parts, 6 hours of building at $25.00 an hour, $0.00 of tools, and a 5-year build life — prebuilt cost $240.00 a year, build cost $210.00 a year, building wins by $30.00 a year. With $1,100.00 of parts, Prebuilt $1,200.00, 5 years, parts $1,100.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $250.00/year, build time $150.00, gap $10.00 (BUYING wins by $10.00/year) — $1,100.00 of parts makes the build $250.00 a year — buying wins by $10.00. With a $900.00 prebuilt, Prebuilt $900.00, 5 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $180.00/year, build $210.00/year, build time $150.00, gap $30.00 (BUYING wins by $30.00/year) — A $900.00 prebuilt costs only $180.00 a year — buying wins by $30.00. With a 7-year build life, Prebuilt $1,200.00, 5 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 7 years: prebuilt $240.00/year, build $150.00/year, build time $150.00, gap -$90.00 (BUILDING wins by $90.00/year) — A build that lasts 7 years costs only $150.00 a year — building wins by $90.00. With a 3-year prebuilt life, Prebuilt $1,200.00, 3 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $400.00/year, build $210.00/year, build time $150.00, gap -$190.00 (BUILDING wins by $190.00/year) — A prebuilt that only lasts 3 years costs $400.00 a year — building wins by $190.00. With a 7-year prebuilt life, Prebuilt $1,200.00, 7 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $171.43/year, build $210.00/year, build time $150.00, gap $38.57 (BUYING wins by $38.57/year) — A prebuilt that lasts 7 years costs $171.43 a year — buying wins by $38.57. With $700.00 of parts and 10 hours at $50.00 an hour, Prebuilt $1,200.00, 5 years, parts $700.00, 10 hours at $50.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $240.00/year, build time $500.00, gap $0.00 (tie) — $700.00 of parts and 10 hours at $50.00 an hour is a tie — $240.00 a year on both sides. With free parts, Prebuilt $1,200.00, 5 years, parts $0.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $30.00/year, build time $150.00, gap -$210.00 (BUILDING wins by $210.00/year) — building wins by $210.00 a year. With 0 hours of build time, Prebuilt $1,200.00, 5 years, parts $900.00, 0 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $180.00/year, build time $0.00, gap -$60.00 (BUILDING wins by $60.00/year) — building wins by $60.00 a year. With a free prebuilt, Prebuilt $0.00, 5 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $0.00/year, build $210.00/year, build time $150.00, gap $210.00 (BUYING wins by $210.00/year) — buying wins by $210.00 a year. With a 1-year build life, Prebuilt $1,200.00, 5 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 1 years: prebuilt $240.00/year, build $1,050.00/year, build time $150.00, gap $810.00 (BUYING wins by $810.00/year) — buying wins by $810.00 a year. With a 10-year prebuilt life, Prebuilt $1,200.00, 10 years, parts $900.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $120.00/year, build $210.00/year, build time $150.00, gap $90.00 (BUYING wins by $90.00/year) — buying wins by $90.00 a year. With $2,000.00 of parts, Prebuilt $1,200.00, 5 years, parts $2,000.00, 6 hours at $25.00/hour, tools $0.00, build 5 years: prebuilt $240.00/year, build $430.00/year, build time $150.00, gap $190.00 (BUYING wins by $190.00/year) — buying wins by $190.00 a year.

Output · formula · meaning

Who uses this

• The gamer pricing a first build: they learn $900.00 of parts plus 6 hours of their time costs $210.00 a year against a $1,200.00 prebuilt’s $240.00 — and they check the $1,050.00 reverse to see the parts cost that would tie the two exactly.
• The builder short on time: they learn 12 hours of building ties the two — and they check the 4-year reverse to see the build lifespan where the winner flips.
• The shopper eyeing a cheap prebuilt: they learn a $900.00 prebuilt wins by $30.00 a year — and they check the $550.00 reverse to see the prebuilt price where buying wins by exactly $100.00 a year.
• The builder with expensive parts: they learn $1,100.00 of parts flips the answer to buying by $10.00 a year — and they check the $800.00 reverse to see the parts cost where building wins by exactly $50.00 a year.

Accuracy & limitations

The math is first-principles: each yearly cost is the price (plus the build time’s value and tools, for the build) divided by the lifespan, rounded to cents half-up, and the gap is the build yearly cost minus the prebuilt yearly cost from the rounded costs. The winner is decided from the rounded gap; a rounded gap of exactly $0.00 is a tie. What the model cannot do is price YOUR build’s remaining life: it ignores performance per dollar (a self-built PC usually gets faster parts for the money), warranty (a prebuilt usually has one warranty for the whole machine; parts have separate warranties), the risk of a bad part or a build mistake (a prebuilt is tested before it ships), the fun of building (worth something even if the calculator charges you for the hours), and resale value at the end (a self-built PC usually resells for less as a whole machine — that favours buying and is NOT in these numbers); the parts list is your best guess, not a quote; and the lifespan is your guess too — a prebuilt’s warranty and a build’s upgrade path both stretch it. Use it to find the build lifespan where the winner flips — then check real parts prices and prebuilt deals before you decide.

Frequently asked questions