Strategy
Estimate a rival's ad spend from share-of-voice against your own.
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- Claude, via MCP
How can I estimate a competitor's ad spend?
Use share of voice as a proxy. Total market spend ≈ your spend ÷ your share of voice, and the competitor's spend ≈ total market spend × their share of voice. If you spend ₹4 lakh at 18% share of voice and a competitor holds 32%, they spend about ₹7.1 lakh, 1.8 times you.
A rival at 32% SOV is likely spending ~$71,111/month, about $31,111 more than you. You don’t have to match it; out-target and out-convert in the segments you can own instead of buying share everywhere.
Assumes spend maps roughly to share of voice within the same auction, a solid directional estimate, not a billing statement.
About this calculator
You can't see a competitor's ad account, but you can usually see their share of voice from an auction-insights or SOV tool, and since spend and share of voice move together within the same auction, that's enough to back into a credible estimate of what they're spending. This calculator does that math so you know roughly what you're up against before deciding whether to chase their budget or out-target it instead.
How to use it
- Enter your own monthly ad spend and your share of voice, your impression share within the category, from an auction-insights or SOV report.
- Enter the competitor's share of voice from the same source.
- Read the estimated total market spend, the competitor's estimated spend, the dollar gap between you, and how many times over they outspend you.
Methodology
The model assumes spend maps roughly proportionally to share of voice within the same auction. Total market spend is estimated as your spend divided by your share of voice: your spend ÷ (your SOV ÷ 100).
The competitor's estimated spend is that total market spend multiplied by their share of voice: total market spend × (competitor SOV ÷ 100).
The spend gap is competitor spend minus your spend, and the ratio (how many times over they outspend you) is competitor spend divided by your spend.
This is a directional estimate, not a billing statement. It assumes both of you are competing in a comparable auction with similar targeting, real-world differences in bidding strategy, targeting precision, and ad quality mean actual spend can diverge from this proportional estimate.
Competitor spend from share of voice
Total market spend = Your spend ÷ Your share of voice Competitor spend = Total market spend × Competitor share of voice Spend gap = Competitor spend − Your spend Outspend ratio = Competitor spend ÷ Your spend
- Share of voice
- A brand's share of the advertising presence in a market: impressions, impression share or ad mentions.
- Your spend
- Your monthly spend in the same channel and market the share-of-voice figures cover.
The model assumes spend and share of voice are proportional, which holds only roughly. A competitor with better ads, higher quality scores or cheaper audiences gets more share per rupee. Treat the answer as a range, perhaps ±30%, and check it against other signals such as their number of active ads.
Worked example: a search competitor with 32% share of voice
A company spends ₹4,00,000 a month on Google Search. Auction insights for its main campaign show its impression share at about 18% and a competitor's overlap suggesting about 32%.
- Total market spend = ₹4,00,000 ÷ 18% = ₹22,22,222.
- Competitor spend = ₹22,22,222 × 32% = ₹7,11,111.
- Spend gap = ₹7,11,111 − ₹4,00,000 = ₹3,11,111 a month.
- Outspend ratio = ₹7,11,111 ÷ ₹4,00,000 = 1.78×.
Closing the gap with budget alone would cost about ₹3.1 lakh more a month. It is usually cheaper to win where it matters: the highest-intent keywords, the regions with the best close rates and the hours when buyers search. Check where you are losing impression share to budget versus rank with the impression share opportunity matrix.
How much share of voice do you need?
Share of voice matters most relative to market share. Advertising effectiveness research has long linked a share of voice above market share with growth, an idea known as excess share of voice. As a working guide:
- Share of voice above market share: likely to gain share over time.
- Roughly equal: likely to hold.
- Below market share: at risk of losing share unless efficiency is unusually high.
For search specifically, aim for high impression share on your highest-intent terms rather than across every keyword.
Competitor spend in India vs the US
Indian search markets can have many small advertisers bidding sporadically, which makes share-of-voice estimates noisy week to week. Use a month of auction insights. On Meta, the Ad Library shows which ads a competitor is running and since when, which indicates scale even without spend figures. For Indian click prices by sector, see Google Ads CPC in India by industry.
US markets often have a few large advertisers holding most impression share on core terms. Third-party tools estimate competitor spend from rankings and CPC data, but their figures are estimates too; compare them with this calculation and treat agreement between methods as more reliable than either alone.
Common competitor benchmarking mistakes
- Mixing share of voice from one channel with spend from another.
- Treating the estimate as exact and matching it rupee for rupee.
- Using a single week of auction insights, which can swing widely.
- Assuming a competitor's spend is working. High spend can also be wasted spend.
- Ignoring organic share of voice, which can matter more than paid in some categories.
Sources
- About impression share, Google Ads Help. Accessed 2026-10-19.
FAQ
It's a reasonable directional signal, not a precise figure. Share of voice and spend are correlated within the same auction, but factors like Quality Score, targeting efficiency, and bid strategy mean two advertisers can buy different amounts of SOV for the same dollar. Treat the output as "roughly this much," not an exact number.
No, and usually shouldn't try to. Out-targeting and out-converting in the segments where you have a real edge is more capital-efficient than trying to outbid a bigger budget everywhere. Use the gap to decide where to concentrate, not as pressure to match total spend.
Auction insights reports in Google Ads and Microsoft Ads show impression share versus competitors directly. Third-party competitive intelligence tools (SEMrush, SpyFu, SimilarWeb and similar) provide broader SOV estimates across search and social if you need visibility beyond your own auction data.
Use it to prioritize, not panic. A large gap in a segment where the competitor is heavily invested usually means they've found something working there; look instead for segments with lower competitor SOV where your budget goes further and you can build a defensible position before they notice.
Use search impression share for your own campaigns and the auction insights report for competitors' overlap and impression share on the same auctions. Google explains how impression share is calculated in its help centre.
Not from the platforms. Google and Meta do not disclose other advertisers' spend, except for political and social issue ads in some ad libraries. Every method is an estimate.
Only where it pays. Concentrate on the keywords, audiences and regions where your conversion and close rates are strongest, so each rupee wins more than theirs.
Numbers looking off?
If the model says one thing and the pipeline says another, that gap is usually where the revenue is. A 30-minute call finds it.
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